Xiaoqing Li, Lizhi Zhang, Ruiqi Wang et al.

IEEE Transactions on Industry Applications • 2023

Biogas-solar-wind integrated energy systems are effective for optimizing rural energy consumption and improving agricultural production. The performance of an integrated energy system generally depends on its capacity configuration. However, the uncertainties of renewable energy sources and loads deepen the coupling relationship between the capacity configuration and energy dispatching of integrated energy systems, which makes optimizing the capacity difficult. We propose a two-stage robust optimization model for the capacity configuration of a biogas-solar-wind integrated energy system that is applicable to rural areas. First, a framework of the biogas-solar-wind integrated energy system was designed and diverse evaluation indices were introduced. Then, the integrated energy system model was transformed into a two-stage robust optimization problem, where the column-and-constraint generation algorithm is used to solve the installed capacity problem of the system equipment in the first stage, and the nested column-and-constraint generation algorithm is used to optimize the energy dispatching schedule in the second stage. Finally, the proposed model was applied to a rural area in China to confirm the rationality and effectiveness of the optimization results.

Neevatika Verma, Narendra Kumar, Saket Gupta et al.

Protection and Control of Modern Power Systems • 2023

Emerging sub-synchronous interactions (SSI) in wind-integrated power systems have added intense attention after numerous incidents in the US and China due to the involvement of series compensated transmission lines and power electronics devices. SSI phenomenon occurs when two power system elements exchange energy below the synchronous frequency. SSI phenomenon related to wind power plants is one of the most significant challenges to maintaining stability, while SSI phenomenon in practical wind farms, which has been observed recently, has not yet been described on the source of conventional SSI literature. This paper first explains the traditional development of SSI and its classification as given by the IEEE, and then it proposes a classification of SSI according to the current research status, reviews several mitigation techniques and challenges, and discusses analysis techniques for SSI. The paper also describes the effect of the active damping controllers, control scheme parameters, degree of series compensation, and various techniques used in wind power plants (WPPs). In particular, a supplementary damping controller with converter controllers in Doubly Fed Induction Generator based WPPs is briefly pronounced. This paper provides a realistic viewpoint and a potential outlook for the readers to properly deal with SSI and its mitigation techniques, which can help power engineers for the planning, economical operation, and future expansion of sustainable development.

F. H. Malik, Muhammad Waseem Khan, Tauheed Ur Rahman et al.

Energies • 2024

The fast growth of the world’s energy demand in the modernized world has stirred many countries around the globe to focus on power generation by abundantly available renewable energy resources. Among them, wind energy has attained significant attention owing to its environment-friendly nature along with other fabulous advantages. However, wind-integrated power systems experience numerous voltage instability complexities due to the sporadic nature of wind. This paper comprehensively reviews the problems of voltage instability in wind-integrated power systems, its causes, consequences, improvement techniques, and implication of grid codes to keep the operation of the network secure. Thorough understanding of the underlying issues related to voltage instability is necessary for the development of effective mitigation techniques in order to facilitate wind integration into power systems. Therefore, this review delves into the origin and consequences of voltage instability, emphasizing its adverse impacts on the performance and reliability of power systems. Moreover, it sheds light on the challenges of integrating wind energy with existing grids. This manuscript provides a comprehensive overview of the essential features required for critical analysis through a detailed examination of Voltage Stability Indices (VSIs). To address voltage stability issues in wind-integrated power systems, this review examines diverse techniques proposed by researchers, encompassing the tools utilized for assessment and mitigation. Therefore, in the field of power system operation and renewable energy integration, this manuscript serves as a valuable resource for researchers by comprehensively addressing the complexities and challenges associated with voltage instability in wind-integrated power systems.

D. Pattison, M. Segovia Garcia, W. Xie et al.

Wind Energy • 2016

<jats:title>Abstract</jats:title><jats:p>A novel architecture and system for the provision of Reliability Centred Maintenance (RCM) for offshore wind power generation is presented. The architecture was developed by conducting a bottom‐up analysis of the data required to support RCM within this specific industry, combined with a top‐down analysis of the required maintenance functionality. The architecture and system consists of three integrated modules for intelligent condition monitoring, reliability and maintenance modelling, and maintenance scheduling that provide a scalable solution for performing dynamic, efficient and cost‐effective preventative maintenance management within this extremely demanding renewable energy generation sector. The system demonstrates for the first time the integration of state‐of‐the‐art advanced mathematical techniques: Random Forests, dynamic Bayesian networks and memetic algorithms in the development of an intelligent autonomous solution. The results from the application of the intelligent integrated system illustrated the automated detection of faults within a wind farm consisting of over 100 turbines, the modelling and updating of the turbines' survivability and creation of a hierarchy of maintenance actions, and the optimizing of the maintenance schedule with a view to maximizing the availability and revenue generation of the turbines. © 2015 The Authors. <jats:italic>Wind Energy</jats:italic> published by John Wiley &amp; Sons Ltd</jats:p>

SM. Alamelu, R.P.Kumudini Devi

Wind Engineering • 2010

<jats:p> The depletion of fossil fuel reserves, emission of greenhouse gases and the uneven distribution of existing reserves led the countries to look for sustainable alternatives, especially wind power. In India mostly Squirrel cage induction generators (SCIG) are used for extracting energy from the wind. Induction generators inject real power to the grid and absorb reactive power from grid. Normally, fixed capacitors of rating equal to no-load compensation are installed at the wind-turbine. Reactive power absorbed by the SCIG over and above the no-lad compensation is dependent on the operating condition. To compensate for the reactive power (over and above the no-load compensation) dynamic VAR compensator can be installed at the point of common coupling. When the wind-farm is connected to a weak grid there may be a problem with wind penetration into the grid. UPFC (a versatile FACTS controller) will be able to alleviate the problems associated with fixed speed wind-farms that are connected to a weak grid. In this paper finding the location and capacity of the UPFC for minimisation of power generation cost is posed as a non-linear optimization problem. An efficient Primal-Dual Interior Point algorithm in conjunction with second order sensitivity analysis is made use for solving the above problem. The optimal line placement for wind penetration in terms of marginal values of UPFC variables are identified using first order sensitivity analysis. Second order sensitivity analysis has been employed to identify the optimal line placement for highest cost savings. Further actual cost savings and optimal control settings of UPFC are evaluated by actually placing UPFC in each line. The proposed approach is tested on a sample 9-bus system using the program developed in Matlab and the results are encouraging. The results indicate that the estimation of optimal placement of UPFC for a large system is possible reducing the computation time involved. </jats:p>

David Rehnlund, Edina Klein, Miriam Edel et al.

ECS Meeting Abstracts • 2020

<jats:p> Microbial cultivation with the aid of microfluidic flow chambers has a great potential to form biofilms on an easy to handle laboratory scale. Our microfluidic cultivation platform with a modular design offers versatility and precision in terms of simulating different environments to study multiple growth conditions<jats:sup>1</jats:sup>. Thus, a long-term cultivation of biofilms can easily be obtained with the possibility of integrated on-line optical analysis. In this paper we will present our recent development of a bioelectrochemical microfluidic platform that allows cultivation and characterization of exoelectrogenic biofilms under anoxic conditions.</jats:p> <jats:p>Electroactive biofilms will be cultivated and characterized in the microfluidic bioelectrochemical system focusing on electroactive microorganisms such as <jats:italic>Shewanella oneidensis</jats:italic>. The conductive intracellular protein chain of these microbes enables extracellular electron transfer (EET) from the cytoplasm through the cell membranes to an insoluble electron acceptor, such as an anode <jats:sup>2</jats:sup>. Different deletion strains were cultivated and could be examined and compared with each other by chronoamperometry, electrochemical impedance spectroscopy, cyclic voltammetry and confocal laser scanning microscopy (CLSM). Genetically engineered strains focus on probing key genes that affect the biofilm forming properties of <jats:italic>Shewanella oneidensis</jats:italic> <jats:sup>3</jats:sup>. In-situ fluorescence microscopy studies of biofilm formation and interaction will also be presented based on our modular microfluidic bioelectrochemical platform. We will also present our ongoing research on artificial electroactive biofilms that integrate electrodeposited nanostructures with a biocompatible hydrogel to form an artificial biofilm matrix.</jats:p> <jats:p>In summary, electroactive biofilm growth under anoxic conditions using an anode as electron sink can be studied using our microfluidic flow technology. Examples of the versatility of the system as well as future outlooks on further biofilm growth conditions will be presented.</jats:p> <jats:p> <jats:bold>References</jats:bold> </jats:p> <jats:p>1. Hansen, S. H. <jats:italic>et al.</jats:italic> Machine-assisted cultivation and analysis of biofilms. <jats:italic>Sci. Rep.</jats:italic> <jats:bold>9</jats:bold>, 8933 (2019).</jats:p> <jats:p>2. Richter, K., Schicklberger, M. &amp; Gescher, J. Dissimilatory Reduction of Extracellular Electron Acceptors in Anaerobic Respiration. <jats:italic>Appl. Environ. Microbiol.</jats:italic> 913–921 (2012). doi:10.1128/AEM.06803-11</jats:p> <jats:p>3. Arinda, T. <jats:italic>et al.</jats:italic> Addition of Riboflavin-Coupled Magnetic Beads Increases Current Production in Bioelectrochemical Systems via the Increased Formation of Anode-Biofilms. <jats:italic>Front. Microbiol.</jats:italic> <jats:bold>10</jats:bold>, 1–8 (2019).</jats:p>

Roozbeh Bakhshi, Peter Sandborn

Wind Energy • 2020

<jats:title>Abstract</jats:title><jats:p>Wind energy is an important source of renewable energy with significant untapped potential around the world. However, the cost of wind energy production is high, and efforts to lower the cost of energy generation will help enable more widespread use of wind energy. Yaw error reduces the efficiency of turbines as well as lowers the reliability of key components in turbines. Light detection and ranging (LIDAR) devices can correct the yaw error; however, they are expensive, and there is a trade‐off between their costs and benefits. In this study, a stochastic discrete‐event simulation was developed that models the operation of a wind farm. We maximize the net present value (NPV) changes associated with using LIDAR devices in a wind farm and determine the optimum number of LIDAR devices and their associated turbine stay time as a function of number of turbines in the wind farm for specific turbine sizes. The outcome of this work will help wind farm owners and operators make informed decisions about purchasing LIDAR devices for their wind farms.</jats:p>

Rajesh Karki, Dinesh Dhungana, Roy Billinton

Applied Sciences • 0

<jats:p>Adverse environmental impacts of carbon emissions are causing increasing concerns to the general public throughout the world. Electric energy generation from conventional energy sources is considered to be a major contributor to these harmful emissions. High emphasis is therefore being given to green alternatives of energy, such as wind and solar. Wind energy is being perceived as a promising alternative. This source of energy technology and its applications have undergone significant research and development over the past decade. As a result, many modern power systems include a significant portion of power generation from wind energy sources. The impact of wind generation on the overall system performance increases substantially as wind penetration in power systems continues to increase to relatively high levels. It becomes increasingly important to accurately model the wind behavior, the interaction with other wind sources and conventional sources, and incorporate the characteristics of the energy demand in order to carry out a realistic evaluation of system reliability. Power systems with high wind penetrations are often connected to multiple wind farms at different geographic locations. Wind speed correlations between the different wind farms largely affect the total wind power generation characteristics of such systems, and therefore should be an important parameter in the wind modeling process. This paper evaluates the effect of the correlation between multiple wind farms on the adequacy indices of wind-integrated systems. The paper also proposes a simple and appropriate probabilistic analytical model that incorporates wind correlations, and can be used for adequacy evaluation of multiple wind-integrated systems.</jats:p>

Andrea Capodaglio, Daniele Cecconet, Daniele Molognoni

Processes • 0

<jats:p>Microbial Fuel Cells (MFCs) represent a still relatively new technology for liquid organic waste treatment and simultaneous recovery of energy and resources. Although the technology is quite appealing due its potential benefits, its practical application is still hampered by several drawbacks, such as systems instability (especially when attempting to scale-up reactors from laboratory prototypes), internally competing microbial reactions, and limited power generation. This paper is an attempt to address some of the issues related to MFC application in wastewater treatment with a simulation model. Reactor configuration, operational schemes, electrochemical and microbiological characterization, optimization methods and modelling strategies were reviewed and have been included in a mathematical simulation model written with a multidisciplinary, multi-perspective approach, considering the possibility of feeding real substrates to an MFC system while dealing with a complex microbiological population. The conclusions drawn herein can be of practical interest for all MFC researchers dealing with domestic or industrial wastewater treatment.</jats:p>

Xavier Alexis Walter, Irene Merino-Jimenez, John Greenman et al.

ECS Meeting Abstracts • 2018

<jats:p> The main competitive advantage of the microbial fuel cell (MFC) technology is to generate electricity from organic waste, which is otherwise considered expensive to treat; as such, interest in this field has intensified over the two last decades. Efforts have mainly focussed on improving the materials employed, the design configuration and the energy-harvesting peripherals. Many improvement solutions have been proposed within the last decade, more and more pilot-scale systems feeding on various kinds of feedstock have been tested (e.g. domestic wastewater, brewery waste, marine sediments, urine). A previous field trial at Glastonbury Music Festival has already demonstrated the feasibility of directly using urine from festival goers to light-up a urinal, thereby setting a benchmark in urine fuelled-MFCs for self-sustainable applications [1]. Furthermore, the concept of self-stratifying membraneless MFC (SSM-MFC) has also been reported. This approach allows scaling-up units’ sizes without significant power density losses, within the tested range (from 900 mL to 5000mL), a factor that has proven an obstacle in previous studies. This design had only been tested under controlled laboratory conditions and never trialled under real usage conditions [2, 3]. </jats:p> <jats:p>In the current study the results of an autonomous system, which was tested at the Glastonbury Music Festival 2016 are presented. To perform this trial, large MFC modules were built, tested and integrated in a setup that comprised a urinal, a stack of 12 SSM-MFCs modules, and an energy management control system harvesting the generated energy to power the lighting of the urinal. The urinal was large enough to accommodate 12 users at any given time and consisted of troughs directing urine to a buffer tank. This tank, equipped with an over flow redirecting excess urine, was connected to a passive feeding mechanism that was supplying urine to a MFC stack of 12 modules every time a volume of 9 L was reached. The stack was set with 6 independent cascades, each having 2 MFC modules electrically connected in parallel. Each module of the cascade comprised 38 MFCs submerged in the same electrolyte and electrically connected in parallel. All six cascades were electrically connected in series. The energy was then harvested and stored in a battery bank. At night (≈9h30 duty-cycles), the control board was redirecting the energy towards 6 LED strips (2.862W) lighting the urinal. </jats:p> <jats:p>Results from laboratory conditions have shown that the power density of a single module was ~2.75 W.m<jats:sup>-3</jats:sup>, whereas under real conditions the power density ranged from ~1.70 to ~2.36 W.m<jats:sup>-3</jats:sup> (total volumetric footprint). The energy harvested from the undiluted urine was sufficient to power the PEE POWER® lights for 9h30 every day. Under laboratory conditions, at 44h hydraulic retention time (HRT) the COD was reduced from 5.586 mg COD.L<jats:sup>-1</jats:sup> to 0.625 mg COD.L<jats:sup>-1</jats:sup> (88%); the nitrogen was also reduced by 29%. In the field, with a HRT of 11h40, the COD decreased by 48% and the total nitrogen content by 13%. When plotting data from the laboratory tests together with the ones of the field trial, the fitted Michaelis-Menten curve (r<jats:sup>2</jats:sup>=0.960) indicates that with a HRT of ≈64h, the COD could be reduced to the European Union standard for discharge (0.125 mg COD.L<jats:sup>-1</jats:sup>). Compared to the 2015 field trial benchmark [1], the present system demonstrates a 37 % higher COD removal with a 50% shorter HRT, and produced ≈30% more energy in a third of the total volumetric footprint. Overall, these results correspond to an over 7-fold technological improvement. </jats:p> <jats:p>[1] Ieropoulos IA, Stinchcombe A, Gajda I, Forbes S, Merino-Jimenez I, Pasternak G, Sanchez-Herranz D and Greenman J. Pee power urinal - microbial fuel cell technology field trials in the context of sanitation. Environ. Sci.-Wat. Res. Technol. 2016;2:336-343 </jats:p> <jats:p>[2] Walter XA, Gajda I, Forbes S, Winfield J, Greenman J and Ieropoulos I. Scaling-up of a novel, simplified MFC stack based on a self-stratifying urine column. Biotechnology for Biofuel 2016;9:93 </jats:p> <jats:p>[3] Walter XA, Stinchcombe A, Greenman J and Ieropoulos I. Urine transduction to usable energy: a modular MFC approach for smartphone and remote system charging. Applied Energy 2017;192:575-581 </jats:p>

Glen-Oliver. F. Gowers, Oliver Vince, John-Henry Charles et al.

Genes • 0

<jats:p>Microbial communities in remote locations remain under-studied. This is particularly true on glaciers and icecaps, which cover approximately 11% of the Earth’s surface. The principal reason for this is the inaccessibility of most of these areas due to their extreme isolation and challenging environmental conditions. While remote research stations have significantly lowered the barrier to studying the microbial communities on icecaps, their use has led to a bias for data collection in the near vicinity of these institutions. Here, miniaturisation of a DNA sequencing lab suitable for off-grid metagenomic studies is demonstrated. Using human power alone, this lab was transported across Europe’s largest ice cap (Vatnajökull, Iceland) by ski and sledge. After 11 days of unsupported polar-style travel, a metagenomic study of a geothermal hot spring gorge was conducted on the remote northern edge of the ice cap. This tent-based metagenomic study resulted in over 24 h of Nanopore sequencing, powered by solar power alone. This study demonstrates the ability to conduct DNA sequencing in remote locations, far from civilised resources (mechanised transport, external power supply, internet connection, etc.), whilst greatly reducing the time from sample collection to data acquisition.</jats:p>

Foziah Gazzawe, Marwan Albahar

F1000Research • 0

<ns3:p>Background The farming industry faces continuous threats from pest control and farm security issues because rodents cause significant damage to crops and disrupt farm operations. Traditional pest control methods require continuous human interaction which proves both resource-intensive and inefficient. Modern agricultural practices benefit from sustainable solutions through the combination of renewable energy with smart technologies. Method The research presents an innovative solar-powered motion-sensor system that utilizes OpenCV-based image analysis to detect and classify rodent intruders on farmland autonomously. The system depends on solar panels for energy autonomy while employing computer vision to monitor threats in real time and classify them. Results The system demonstrates its ability to detect and prevent rodent intruders according to initial testing results. The OpenCV system uses motion sensor signals to analyze movement patterns before distinguishing rodents from other detected objects. The solar-powered system operates continuously which decreases human intervention needs and enhances farm surveillance capabilities. The model demonstrates its capability to defend crops from rodent damage and enhance farm resistance against land degradation threats. Conclusion The proposed system demonstrates progress in uniting renewable energy systems with smart surveillance technologies to mitigate agricultural risks. The current system encounters problems with detecting wild animals beyond rodents as well as tracking rodent activity beneath ground level. Future developments could include improved pest capture systems alongside enhanced surveillance features for detecting both unauthorized human intruders and large animals. The research shows that solar power systems need to be connected with automated monitoring technology to create sustainable agricultural operations that are efficient and resilient.</ns3:p>

Liesje De Schamphelaire, Angela Cabezas, Massimo Marzorati et al.

Applied and Environmental Microbiology • 2010

<jats:title>ABSTRACT</jats:title> <jats:p> By placing the anode of a sediment microbial fuel cell (SMFC) in the rhizosphere of a rice plant, root-excreted rhizodeposits can be microbially oxidized with concomitant current generation. Here, various molecular techniques were used to characterize the composition of bacterial and archaeal communities on such anodes, as influenced by electrical circuitry, sediment matrix, and the presence of plants. Closed-circuit anodes in potting soil were enriched with <jats:italic>Desulfobulbus</jats:italic> -like species, members of the family <jats:italic>Geobacteraceae</jats:italic> , and as yet uncultured representatives of the domain <jats:italic>Archaea</jats:italic> . </jats:p>

Paul Bertheau, Catherina Cader, Hendrik Huyskens et al.

Resources • 0

<jats:p>Many people in African countries lack access to sufficient electricity supply due to missing infrastructure of the centralized conventional power generation system. In order to provide electricity to a wider part of the population, it is necessary to exploit the vast renewable resources in African countries. Therefore, this paper scrutinizes the economic advantages of photovoltaic-based hybrid systems over fossil fuel-based power generation. A simulation model is applied in order to calculate the cost advantage of hybrid systems compared to diesel-only systems for the entire continent on a long term basis by applying two scenarios: one based on world market diesel prices and the other one based on national diesel prices. The results indicate that average power generation costs per country can be reduced by up to 0.11 €/kWh considering world market diesel prices and by up to 0.48 €/kWh considering national diesel prices. Furthermore, the effect of diesel fuel subsidies and taxes on the renewable energy potential and the respective savings are examined. These findings may ameliorate the policy development according to fossil fuel subsidies and taxes and demonstrate the advantages of decentralized renewable hybrid systems especially in rural areas of Africa.</jats:p>

Iwona Gajda, John Greenman, Chris Melhuish et al.

Scientific Reports • 0

<jats:title>Abstract</jats:title><jats:p>This study presents a simple and sustainable Microbial Fuel Cell as a standalone, self-powered reactor for <jats:italic>in situ</jats:italic> wastewater electrolysis, recovering nitrogen from wastewater. A process is proposed whereby the MFC electrical performance drives the electrolysis of wastewater towards the self-generation of catholyte within the same reactor. The MFCs were designed to harvest the generated catholyte in the internal chamber, which showed that liquid production rates are largely proportional to electrical current generation. The catholyte demonstrated bactericidal properties, compared to the control (open-circuit) diffusate and reduced observable biofilm formation on the cathode electrode. Killing effects were confirmed using bacterial kill curves constructed by exposing a bioluminescent <jats:italic>Escherichia coli</jats:italic> target, as a surrogate coliform, to catholyte where a rapid kill rate was observed. Therefore, MFCs could serve as a water recovery system, a disinfectant/cleaner generator that limits undesired biofilm formation and as a washing agent in waterless urinals to improve sanitation. This simple and ready to implement MFC system can convert organic waste directly into electricity and self-driven nitrogen along with water recovery. This could lead to the development of energy positive bioprocesses for sustainable wastewater treatment.</jats:p>

Lisa Keller, D. Colman, E. Boyd

PNAS Nexus • 2023

Abstract Natural thermal geysers are hot springs that periodically erupt liquid water, steam, and gas. They are found in only a few locations worldwide, with nearly half located in Yellowstone National Park (YNP). Old Faithful geyser (OFG) is the most iconic in YNP and attracts millions of visitors annually. Despite extensive geophysical and hydrological study of geysers, including OFG, far less is known of the microbiology of geysed waters. Here, we report geochemical and microbiological data from geysed vent water and vent water that collects in a splash pool adjacent to OFG during eruptions. Both waters contained microbial cells, and radiotracer studies showed that they fixed carbon dioxide (CO2) when incubated at 70°C and 90°C. Shorter lag times in CO2 fixation activity were observed in vent and splash pool waters incubated at 90°C than 70°C, suggesting cells are better adapted or acclimated to temperatures like those in the OFG vent (∼92–93°C). 16S rDNA and metagenomic sequence data indicated that both communities are dominated by the autotroph Thermocrinis, which likely fuels productivity through the aerobic oxidation of sulfide/thiosulfate in erupted waters or steam. Dominant OFG populations, including Thermocrinis and subdominant Thermus and Pyrobaculum strains, exhibited high-strain level genomic diversity (putative ecotypes) relative to populations from nongeysing YNP hot springs that is attributed to the temporal chemical and temperature dynamics caused by eruptions. These findings show that OFG is habitable and that its eruption dynamics promote genomic diversity, while highlighting the need to further research the extent of life in geyser systems such as OFG.

Wulin Yang, Bruce E. Logan

Environmental Science: Water Research &amp; Technology • 0

<p>Microbial fuel cell (MFC) cathodes must have high performance and be resistant to water leakage.</p>

Shekhar Nagar, Chandni Talwar, Mikael Motelica-Heino et al.

Frontiers in Microbiology • 0

<jats:p>Sulfur related prokaryotes residing in hot spring present good opportunity for exploring the limitless possibilities of integral ecosystem processes. Metagenomic analysis further expands the phylogenetic breadth of these extraordinary sulfur (S) metabolizing microorganisms as well as their complex metabolic networks and syntrophic interactions in environmental biosystems. Through this study, we explored and expanded the microbial genetic repertoire with focus on S cycling genes through metagenomic analysis of S contaminated hot spring, located at the Northern Himalayas. The analysis revealed rich diversity of microbial consortia with established roles in S cycling such as <jats:italic>Pseudomonas</jats:italic>, <jats:italic>Thioalkalivibrio</jats:italic>, <jats:italic>Desulfovibrio</jats:italic>, and <jats:italic>Desulfobulbaceae</jats:italic> (<jats:italic>Proteobacteria</jats:italic>). The major gene families inferred to be abundant across microbial mat, sediment, and water were assigned to <jats:italic>Proteobacteria</jats:italic> as reflected from the reads per kilobase (RPKs) categorized into translation and ribosomal structure and biogenesis. An analysis of sequence similarity showed conserved pattern of both <jats:italic>dsrAB</jats:italic> genes (<jats:italic>n</jats:italic> = 178) retrieved from all metagenomes while other S disproportionation proteins were diverged due to different structural and chemical substrates. The diversity of S oxidizing bacteria (SOB) and sulfate reducing bacteria (SRB) with conserved (r)<jats:italic>dsrAB</jats:italic> suggests for it to be an important adaptation for microbial fitness at this site. Here, (i) the oxidative and reductive <jats:italic>dsr</jats:italic> evolutionary time–scale phylogeny proved that the earliest (but not the first) <jats:italic>dsrAB</jats:italic> proteins belong to anaerobic <jats:italic>Thiobacillus</jats:italic> with other (<jats:italic>rdsr</jats:italic>) oxidizers, also we confirm that (ii) SRBs belongs to δ-<jats:italic>Proteobacteria</jats:italic> occurring independent lateral gene transfer (LGT) of <jats:italic>dsr</jats:italic> genes to different and few novel lineages. Further, the structural prediction of unassigned DsrAB proteins confirmed their relatedness with species of <jats:italic>Desulfovibrio</jats:italic> (TM score = 0.86, 0.98, 0.96) and <jats:italic>Archaeoglobus fulgidus</jats:italic> (TM score = 0.97, 0.98). We proposed that the genetic repertoire might provide the basis of studying time–scale evolution and horizontal gene transfer of these genes in biogeochemical S cycling.</jats:p>

Kamila Knapik, Manuel Becerra, María-Isabel González-Siso

Scientific Reports • 0

<jats:title>Abstract</jats:title><jats:p>Here, we describe the metagenome composition of a microbial community in a hot spring sediment as well as a sequence-based and function-based screening of the metagenome for identification of novel xylanases. The sediment was collected from the Lobios Hot Spring located in the province of Ourense (Spain). Environmental DNA was extracted and sequenced using Illumina technology, and a total of 3.6 Gbp of clean paired reads was produced. A taxonomic classification that was obtained by comparison to the NCBI protein nr database revealed a dominance of Bacteria (93%), followed by Archaea (6%). The most abundant bacterial phylum was Acidobacteria (25%), while Thaumarchaeota (5%) was the main archaeal phylum. Reads were assembled into contigs. Open reading frames (ORFs) predicted on these contigs were searched by BLAST against the CAZy database to retrieve xylanase encoding ORFs. A metagenomic fosmid library of approximately 150,000 clones was constructed to identify functional genes encoding thermostable xylanase enzymes. Function-based screening revealed a novel xylanase-encoding gene (<jats:italic>XynA3</jats:italic>), which was successfully expressed in <jats:italic>E</jats:italic>. <jats:italic>coli</jats:italic> BL21. The resulting protein (41 kDa), a member of glycoside hydrolase family 11 was purified and biochemically characterized. The highest activity was measured at 80 °C and pH 6.5. The protein was extremely thermostable and showed 94% remaining activity after incubation at 60 °C for 24 h and over 70% remaining activity after incubation at 70 °C for 24 h. Xylanolytic activity of the XynA3 enzyme was stimulated in the presence of β-mercaptoethanol, dithiothreitol and Fe<jats:sup>3+</jats:sup> ions. HPLC analysis showed that XynA3 hydrolyzes xylan forming xylobiose with lower proportion of xylotriose and xylose. Specific activity of the enzyme was 9080 U/mg for oat arabinoxylan and 5080 U/mg for beechwood xylan, respectively, without cellulase activity.</jats:p>

Christaline George, Chloe Xue Qi Lim, Yan Tong et al.

Frontiers in Microbiology • 0

<jats:p>The Sembawang Hot Spring in Singapore lies at the foot of a major regional geological feature called the Bentong-Raub Suture Zone. Amid an extensively managed surface geothermal park, an undisturbed hot spring emerges with source water at 61°C, pH 6.8, and 1 mg/L dissolved sulfide. A small main pool at the source supported orange-green benthic flocs, whereas the outflow channel with gradually less extreme environmental stress supported extensive vivid green microbial mats. Microscopy revealed that cyanobacterial morphotypes were distinct in flocs and mats at several intervals along the environmental gradient, and we describe a spiraling pattern in the oscillatorian cyanobacteria that may reflect response to poly-extreme stress. Estimation of diversity using 16S rRNA gene sequencing revealed assemblages that were dominated by phototrophic bacteria. The most abundant taxa in flocs at 61°C/1 mg/L sulfide were <jats:italic>Roseiflexus</jats:italic> sp. and <jats:italic>Thermosynechococcus elongatus</jats:italic>, whilst the mats at 45.7–55.3°C/0–0.5 mg/L sulfide were dominated by <jats:italic>Oscillatoriales</jats:italic> cyanobacterium MTP1 and <jats:italic>Chloroflexus</jats:italic> sp. Occurrence of diverse chemoautotrophs and heterotrophs reflected known thermal ranges for taxa, and of note was the high abundance of thermophilic cellulolytic bacteria that likely reflected the large allochthonous leaf input. A clear shift in ASV-defined putative ecotypes occurred along the environmental stress gradient of the hot spring and overall diversity was inversely correlated to environmental stress. Significant correlations for abiotic variables with observed biotic diversity were identified for temperature, sulfide, and carbonate. A network analysis revealed three putative modules of biotic interactions that also reflected the taxonomic composition at intervals along the environmental gradient. Overall, the data indicated that three distinct microbial communities were supported within a small spatial scale along the poly-extreme environmental gradient. The findings add to the growing inventory of hot spring microbiomes and address an important biogeographic knowledge gap for the region.</jats:p>

T. Santini, Lucy Gramenz, G. Southam et al.

Frontiers in Microbiology • 2022

Salt lakes are globally significant microbial habitats, hosting substantial novel microbial diversity and functional capacity. Extremes of salinity and pH both pose major challenges for survival of microbial life in terrestrial and aquatic environments, and are frequently cited as primary influences on microbial diversity across a wide variety of environments. However, few studies have attempted to identify spatial and geochemical contributions to microbial community composition, functional capacity, and environmental tolerances in salt lakes, limiting exploration of novel halophilic and halotolerant microbial species and their potential biotechnological applications. Here, we collected sediment samples from 16 salt lakes at pH values that ranged from pH 4 to 9, distributed across 48,000 km2 of the Archaean Yilgarn Craton in southwestern Australia to identify associations between environmental factors and microbial community composition, and used a high throughput culturing approach to identify the limits of salt and pH tolerance during iron and sulfur oxidation in these microbial communities. Geographical distance between lakes was the primary contributor to variation in microbial community composition, with pH identified as the most important geochemical contributor to variation in microbial community composition. Microbial community composition split into two clear groups by pH: Bacillota dominated microbial communities in acidic saline lakes, whereas Euryarchaeota dominated microbial communities in alkaline saline lakes. Iron oxidation was observed at salinities up to 160 g L–1 NaCl at pH values as low as pH 1.5, and sulfur oxidation was observed at salinities up to 160 g L–1 NaCl between pH values 2–10, more than doubling previously observed tolerances to NaCl salinity amongst cultivable iron and sulfur oxidizers at these extreme pH values. OTU level diversity in the salt lake microbial communities emerged as the major indicator of iron- and sulfur-oxidizing capacity and environmental tolerances to extremes of pH and salinity. Overall, when bioprospecting for novel microbial functional capacity and environmental tolerances, our study supports sampling from remote, previously unexplored, and maximally distant locations, and prioritizing for OTU level diversity rather than present geochemical conditions.

Fei-Li Zeng, Yonghong Zhu, Dongling Zhang et al.

Frontiers in Microbiology • 2022

The soil in Yuncheng Salt Lake has serious salinization and the biogeographic environment affects the composition and distribution of special halophilic and salt-tolerant microbial communities in this area. Therefore, this study collected soils at distances of 15, 30, and 45 m from the Salt Lake and used non-saline soil (60 m) as a control to explore the microbial composition and salt tolerance mechanisms using metagenomics technology. The results showed that the dominant species and abundance of salt-tolerant microorganisms changed gradually with distance from Salt Lake. The salt-tolerant microorganisms can increase the expression of the Na+/H+ antiporter by upregulating the Na+/H+ antiporter subunit mnhA-G to respond to salt stress, simultaneously upregulating the genes in the betaine/proline transport system to promote the conversion of choline into betaine, while also upregulating the trehalose/maltose transport system encode genes to promote the synthesis of trehalose to resist a high salt environment.

Yihang Fang, Huifang Xu, Fraklin Hobbs

Sedimentology • 2023

Since the discovery of dolomite, numerous attempts have been made to understand its precipitation mechanism at Earth's surface conditions. One such mechanism relies on a relationship with microbial life, where laboratory synthesis experiments have shown that specific organic molecules, such as polysaccharides, exopolymeric substances and hydrogen sulphide can promote dolomite precipitation. Other mechanisms for precipitating dolomite focus on abiotic chemical environments, such as adding dissolved silica, which lower the dehydration energy barrier for the surface Mg2+‐water complex and promote disordered dolomite precipitation. Modern occurrences of dolomite in the Great Salt Lake, Utah, have been studied since the early 20th Century. The distribution of primary dolomite in the Great Salt Lake is spatially heterogeneous, with only the carbonate mud in the South Arm and ridge‐site between desiccation cracks in the North Arm being dominated by dolomite and calcite, while stromatolites in both Arms and ooidal sands in the North Arm are composed entirely of aragonite. It was proposed that dolomite precipitation in the Great Salt Lake was possibly induced by microbial activities such as organic degradation, bacteria sulphate reduction, or other microbial metabolic by‐products. However, these hypotheses could not explain the lack of dolomite in microbial mats, especially in the North Arm, which is constituted by mostly aragonite with no dolomite. Our results suggest that dissolved silica concentration is the primary control for dolomite and Mg‐clay formation in the Great Salt Lake. Even though the North Arm has a much more concentrated Mg and Ca water from lack of freshwater input, dissolved silica levels in the South Arm (>0.5 mm) and the Ridge‐site (ca 0.5 mm) are much higher than in the North Arm (<0.2 mm). Our finding could also provide a new proxy for reconstructing climate changes in the Great Salt Lake area based on dolomite content variation. Phanerozoic dolomite abundance variations may be linked to global CO2 level that facilitates global chemical weathering and dissolved silica input into palaeo‐ocean.

Shenxiang Zhang, Xian Wei, Xue Cao et al.

Nature Communications • 2024

The demand for lithium extraction from salt-lake brines is increasing to address the lithium supply shortage. Nanofiltration separation technology with high Mg^2+/Li^+ separation efficiency has shown great potential for lithium extraction. However, it usually requires diluting the brine with a large quantity of freshwater and only yields Li^+-enriched solution. Inspired by the process of selective ion uptake and salt secretion in mangroves, we report here the direct extraction of lithium from salt-lake brines by utilizing the synergistic effect of ion separation membrane and solar-driven evaporator. The ion separation membrane-based solar evaporator is a multilayer structure consisting of an upper photothermal layer to evaporate water, a hydrophilic porous membrane in the middle to generate capillary pressure as the driving force for water transport, and an ultrathin ion separation membrane at the bottom to allow Li^+ to pass through and block other multivalent ions. This process exhibits excellent lithium extraction capability. When treating artificial salt-lake brine with salt concentration as high as 348.4 g L^−1, the Mg^2+/Li^+ ratio is reduced by 66 times (from 19.8 to 0.3). This research combines ion separation with solar-driven evaporation to directly obtain LiCl powder, providing an efficient and sustainable approach for lithium extraction. An efficient and cost-effective Mg/Li separation process is necessary for lithium extraction from Salt Lake brines. Inspired by the mangroves, authors developed a direct lithium extraction method from Salt Lake brines through the synergistic effect of an ion separation membrane and a solar evaporator.

Gary E. Belovsky, Chad Larson, Younjin Han et al.

Aquatic Ecology • 2025

<jats:title>Abstract</jats:title> <jats:p>Over 27 years in Great Salt Lake (GSL: Utah, USA), phytoplankton relative abundances of chlorophytes, diatoms and cyanobacteria varied dramatically (monthly &lt; 10–90% for each). This observed variability within the lake was compared to laboratory experimental results with pure cultures (&gt; &gt; 90%) of several of the most common GSL phytoplankton (chlorophyte–<jats:italic>Dunaliella viridis</jats:italic>, diatom–<jats:italic>Nitzschia epithemioides</jats:italic>, cyanobacterium–<jats:italic>Euhalothece</jats:italic> sp.). Maximum abundances and growth rates were measured across ranges of temperature (10–30 °C), salinity (30–150 ppt) and nutrients (nitrogen: 0.0–0.64 mg/L, silica:17–51 mg/L) observed within GSL. Experimental results indicated the abundance and growth rate of <jats:italic>D. viridis</jats:italic> increased as salinity and nitrogen increased and decreased as temperature increased. The abundances and growth rates of <jats:italic>N. epithemioides</jats:italic> and <jats:italic>Euhalothece</jats:italic> decreased as salinity increased, and increased as temperature and nitrogen increased, and <jats:italic>N. epithemioides</jats:italic> increased as silica increased. Observed GSL phytoplankton relative abundances responded to environmental conditions as observed in the experiments, but correlations were weak except for chlorophytes, as diatoms and cyanobacteria relative abundances occasionally increased with unfavorable experimental conditions. The weak correlations between laboratory results and GSL observations could be due to the release of diatoms and cyanobacteria from microbialite biofilms in the lake’s benthos with cold stress and high winds, as a 5–10% release can produce diatom and cyanobacteria phytoplankton relative abundances of 24–48%. This suggests a novel potential link between GSL pelagic and benthic zones.</jats:p>

Osama M. Alian, William J. Brazelton, Karmina A. Aquino et al.

Frontiers in Microbiomes • 0

<jats:p>Oceanic hydrothermal vent systems represent some of the oldest habitats on Earth and serve as analogs for extraterrestrial environments. The Lost City Hydrothermal Field (LCHF) near the Mid-Atlantic Ridge is one such environment, and its large chimneys are unique in hosting actively venting hydrothermal fluids that are primarily controlled by serpentinization reactions in the subseafloor. Microbial communities within LCHF have been studied for insights into their functional adaptations to the warm, alkaline, and dissolved inorganic carbon-limited environment. Metagenomic and mineralogical data collected during a recent expedition to Lost City were analyzed to delineate associations between microbial populations and physical, chemical and biological characteristics of the chimneys. Bacterial 16S rRNA gene sequences show a high degree of putative microdiversity within the relatively dominant genera Desulfotomaculum, Sulfurovum, Thiomicrorhabdus, and Serpentinicella, which represent a large core of the overall LCHF vent bacterial community. This microdiversity relates to the compositional fraction of aragonite, brucite, and calcite minerals within chimney samples rather than just the composition of nearby vent fluids. Although many species are found in both chimneys and venting fluids, the overall microbial community structures in chimney biofilms remain distinct from the hydrothermal fluids that flow through them. Shotgun metagenomic analyses reveal differences among genes predicted to be involved in carbon, methane, nitrogen and sulfur cycling with respect to their correlations to the abundances of specific minerals. These data hint at microenvironmental complexity lost within standard bulk analyses. The findings of this study underscore the need to more closely examine microbe-mineral interactions in natural environments, critically informing not just population-level distributions, but also the functional underpinnings of these extremophile microbial communities.</jats:p>

T. Schuler, J. Kohler, N. Elagina et al.

Frontiers in Earth Science • 2020

Since the first estimates of Svalbard-wide glacier mass balance were made in the early 2000s, there has been great progress in remote sensing and modeling of mass balance, existing field records have been extended, field records at new locations have been added, and there has been considerable environmental change. There is a wide spread in the available estimates of both total mass balance and surface or climatic mass balance, but there is overall agreement that the glaciers on Svalbard have been losing mass since the 1960s, with a tendency toward more negative mass balance since 2000. We define criteria to select data that are representative and of high credibility; this subset shows a more coherent evolution and reduced spread. In addition, we combine individual field mass balance records collected by different groups into a single dataset that samples glaciers across Svalbard and a range of different size classes. We find a close relationship between measured specific surface mass balance and size of the glacier, in such a way that smaller glaciers experience more negative surface mass balances. A qualitatively similar relationship between the accumulation area ratio and glacier area is found for all glaciers in the Svalbard, suggesting that the relation derived from glaciological records is not only an artifact caused by the limited number of samples (n = 12). We apply this relation to upscale measured surface mass balance for a new estimate for all glaciers of Svalbard. Our reconciled estimates are −7 ± 4 Gt a–1 (2000–2019) for the climatic mass balance, and −8 ± 6 Gt a–1 for the total mass balance. The difference between the two represents the sum of frontal ablation and the combined uncertainty, which together amount to ca. −2 ± 7 Gt a–1. While this is consistent with a previous estimate of Svalbard-wide frontal ablation, the uncertainties are large. Furthermore, several large and long-lasting surges have had considerable and multi-year impact on the total mass balance, and in particular on calving rates, emphasizing the need for better-resolved and more frequently updated estimates of frontal ablation.

M. Hopwood, D. Carroll, T. Dunse et al.

The Cryosphere • 2019

Abstract. Freshwater discharge from glaciers is increasing across the Arctic in response to anthropogenic climate change, which raises questions about the potential downstream effects in the marine environment. Whilst a combination of long-term monitoring programmes and intensive Arctic field campaigns have improved our knowledge of glacier–ocean interactions in recent years, especially with respect to fjord/ocean circulation, there are extensive knowledge gaps concerning how glaciers affect marine biogeochemistry and productivity. Following two cross-cutting disciplinary International Arctic Science Committee (IASC) workshops addressing the importance of glaciers for the marine ecosystem, here we review the state of the art concerning how freshwater discharge affects the marine environment with a specific focus on marine biogeochemistry and biological productivity. Using a series of Arctic case studies (Nuup Kangerlua/Godthåbsfjord, Kongsfjorden, Kangerluarsuup Sermia/Bowdoin Fjord, Young Sound and Sermilik Fjord), the interconnected effects of freshwater discharge on fjord–shelf exchange, nutrient availability, the carbonate system, the carbon cycle and the microbial food web are investigated. Key findings are that whether the effect of glacier discharge on marine primary production is positive or negative is highly dependent on a combination of factors. These include glacier type (marine- or land-terminating), fjord–glacier geometry and the limiting resource(s) for phytoplankton growth in a specific spatio-temporal region (light, macronutrients or micronutrients). Arctic glacier fjords therefore often exhibit distinct discharge–productivity relationships, and multiple case-studies must be considered in order to understand the net effects of glacier discharge on Arctic marine ecosystems.

Tingting Ren, Wei Su, Yingchun Mu et al.

Frontiers in Microbiology • 2023

The Chishui River basin is the main production area of the sauce-flavor Baijiu. Due to the particularity of sauce-flavor Baijiu technology, a large site of workshops needs to be built for brewing and storage. Therefore, used the natural karst caves of Guizhou province to manufacture the sauce-flavor Baijiu, which has enriched the connotation of sauce-flavor Baijiu and saved valuable land resources. In this study, the fermentation grains in the seven stages during the Xiasha round of the cave-brewed sauce-flavor Baijiu (CBSB) were detected using a combination of physicochemical analysis, Headspace solid-phase microextraction gas chromatography-mass detection, and Illumina HiSeq sequencing methods. The results showed Unspecified_Leuconostocaceae, Weissella, Unspecified_Bacillaceae, Saccharomycopsis, Thermomyces, and Unspecified_Phaffomycetaceae were the main bacterial and fungal genera in the stacking fermentation (SF). In the cellar fermentation (CF), the Lactobacillus, Unspecified_Lactobacillaceae, Thermoactinomyces, Saccharomycopsis, Unspecified_Phaffomycetaceae, and Wickerhamomyces were the main bacterial and fungal genera. A total of 72 volatiles were detected in the fermented grains. Linear discriminant analysis Effect Size (LEfSe) identified 23 significantly different volatile metabolites in the fermentation process, including 7 esters, 6 alcohols, 4 acids, 3 phenols, 1 hydrocarbon, and 2 other compounds. Redundancy analysis was used to explore the correlation between dominant microbial genera and physicochemical properties. Starch was the main physicochemical property affecting microbial succession in the SF. Acidity, moisture, and reducing sugar were the main driving factors of microbial succession in the CF. The Pearson correlation coefficient revealed the correlation between dominant microbial genera and significantly different volatile flavor substances. A total of 18 dominant microbial genera were associated with significantly different volatile metabolites, Lactobacillus, Weissella, Wickerhamomyces, and Aspergillus were shown to play crucial roles in metabolite synthesis. On this basis, a metabolic map of the dominant microbial genera was established. This study provides a theoretical basis for the production and quality control of sauce-flavor Baijiu brewed in natural karst caves and lays a foundation for studying the link between flavor formation and microorganisms.

Dianye Zhang, Lu Wang, Shuqi Qin et al.

Global Change Biology • 2023

The status of plant and microbial nutrient limitation have profound impacts on ecosystem carbon cycle in permafrost areas, which store large amounts of carbon and experience pronounced climatic warming. Despite the long‐term standing paradigm assumes that cold ecosystems primarily have nitrogen deficiency, large‐scale empirical tests of microbial nutrient limitation are lacking. Here we assessed the potential microbial nutrient limitation across the Tibetan alpine permafrost region, using the combination of enzymatic and elemental stoichiometry, genes abundance and fertilization method. In contrast with the traditional view, the four independent approaches congruently detected widespread microbial nitrogen and phosphorus co‐limitation in both the surface soil and deep permafrost deposits, with stronger limitation in the topsoil. Further analysis revealed that soil resources stoichiometry and microbial community composition were the two best predictors of the magnitude of microbial nutrient limitation. High ratio of available soil carbon to nutrient and low fungal/bacterial ratio corresponded to strong microbial nutrient limitation. These findings suggest that warming‐induced enhancement in soil nutrient availability could stimulate microbial activity, and probably amplify soil carbon losses from permafrost areas.

M. Waldrop, C. Chabot, S. Liebner et al.

The ISME Journal • 2023

Permafrost underlies approximately one quarter of Northern Hemisphere terrestrial surfaces and contains 25–50% of the global soil carbon (C) pool. Permafrost soils and the C stocks within are vulnerable to ongoing and future projected climate warming. The biogeography of microbial communities inhabiting permafrost has not been examined beyond a small number of sites focused on local-scale variation. Permafrost is different from other soils. Perennially frozen conditions in permafrost dictate that microbial communities do not turn over quickly, thus possibly providing strong linkages to past environments. Thus, the factors structuring the composition and function of microbial communities may differ from patterns observed in other terrestrial environments. Here, we analyzed 133 permafrost metagenomes from North America, Europe, and Asia. Permafrost biodiversity and taxonomic distribution varied in relation to pH, latitude and soil depth. The distribution of genes differed by latitude, soil depth, age, and pH. Genes that were the most highly variable across all sites were associated with energy metabolism and C-assimilation. Specifically, methanogenesis, fermentation, nitrate reduction, and replenishment of citric acid cycle intermediates. This suggests that adaptations to energy acquisition and substrate availability are among some of the strongest selective pressures shaping permafrost microbial communities. The spatial variation in metabolic potential has primed communities for specific biogeochemical processes as soils thaw due to climate change, which could cause regional- to global- scale variation in C and nitrogen processing and greenhouse gas emissions.

Bridget B. McGivern, Dylan Cronin, Jared B. Ellenbogen et al.

Nature Microbiology • 2024

With rising global temperatures, permafrost carbon stores are vulnerable to microbial degradation. The enzyme latch theory states that polyphenols should accumulate in saturated peatlands due to diminished phenol oxidase activity, inhibiting resident microbes and promoting carbon stabilization. Pairing microbiome and geochemical measurements along a permafrost thaw-induced saturation gradient in Stordalen Mire, a model Arctic peatland, we confirmed a negative relationship between phenol oxidase expression and saturation but failed to support other trends predicted by the enzyme latch. To inventory alternative polyphenol removal strategies, we built CAMPER, a gene annotation tool leveraging polyphenol enzyme knowledge gleaned across microbial ecosystems. Applying CAMPER to genome-resolved metatranscriptomes, we identified genes for diverse polyphenol-active enzymes expressed by various microbial lineages under a range of redox conditions. This shifts the paradigm that polyphenols stabilize carbon in saturated soils and highlights the need to consider both oxic and anoxic polyphenol metabolisms to understand carbon cycling in changing ecosystems.

K. Lloyd, C. Sheik, B. García-Moreno et al.

Deep Carbon • 2019

Much of the microbial life on Earth resides below the surface in the crust (Figure 18.1) (1), either buried in marine sediments (2) and petroleum deposits (3) or entrained in aquifers within oceanic and terrestrial rocks (Figure 18.2) (4–8), fluid inclusions in salt, permafrost, and ice (9–11), as well as hydrothermal and geothermal fluids (12,13). The study of deep subsurface life has defined our understanding of habitability and expanded our knowledge of the mechanisms that enables life to live in these environments (14). While the study of deep life may seem like a philosophical exercise, understanding this enigmatic biosphere has important real-world implications for assessing the safety and feasibility of underground storage of spent nuclear fuel and other toxic compounds, sequestration of atmospheric CO2, or acquisition of fuels such as tar sands, deep subsurface coal beds, methane hydrates, or fracking (3,5,15). Organisms inhabiting subsurface environments likely have been isolated from the surface world for hundreds to millions of years (16). Thus, their metabolic lifestyles may differ substantially from those of surface organisms. Even though subsurface environments are diverse (Chapter 16, this volume), subsurface microbes share common biological challenges such as limitations of energy, resources, and space, as well as extremes of pressure, pH, osmolarity, and temperature (Chapter 17, this volume). On the other hand, subsurface environments offer biological advantages, too: environmental stability, protection from UV irradiation, and oxygen. These unique subsurface conditions lead to communities that are often phylogenetically and functionally diverse, with extremely slow population turnover times (14,17,18) and efficient energy metabolisms (14,19). Increasingly, the roles of viruses and eukaryotes, in addition to bacteria and archaea, are being recognized in the deep subsurface biosphere (20–25). Several barriers hamper the study of life in Earth’s crust, such as sample acquisition and the difficulty of retrieving sterile, unaltered samples that have not been contaminated by drilling fluid. However, an even bigger hurdle is the difficulty of studying the copious subsurface microbes with no cultured representatives (13,26). Their functional potential must be pieced together from direct assessments of biomolecules or biochemical processes in natural samples. However, even subsurface microbes related to laboratory cultures with “known” functions, may not perform those functions in the natural

P. Douglas, Regina Gonzalez Moguel, K. W. Walter Anthony et al.

Geophysical Research Letters • 2020

The release of long‐stored carbon from thawed permafrost could fuel increased methanogenesis in northern lakes, but it remains unclear whether old carbon substrates released from permafrost are metabolized as rapidly by methanogenic microbial communities as recently produced organic carbon. Here, we apply methane (CH4) clumped isotope (Δ18) and 14C measurements to test whether rates of methanogenesis are related to carbon substrate age. Results from culture experiments indicate that Δ18 values are negatively correlated with CH4 production rate. Measurements of ebullition samples from thermokarst lakes in Alaska and glacial lakes in Sweden indicate strong negative correlations between CH4 Δ18 and the fraction modern carbon. These correlations imply that CH4 derived from older carbon substrates is produced relatively slowly. Relative rates of methanogenesis, as inferred from Δ18 values, are not positively correlated with CH4 flux estimates, highlighting the likely importance of environmental variables other than CH4 production rates in controlling ebullition fluxes.

Ivan Alekseev, Aleksei Zverev, Evgeny Abakumov

Microorganisms • 0

<jats:p>Although ice-free areas cover only about 0.1% of Antarctica and are characterized by harsh environmental conditions, these regions provide quite diverse conditions for the soil-forming process, having various physical and geochemical properties, and also assuring different conditions for living organisms. This study is aimed to determine existing soil microbial communities, their relationship with soil parameters and the influence of anthropogenic activity in Larsemann Hills, Eastern Antarctica. The soil microbiome was investigated at different locations using 16S rRNA gene pyrosequencing. The taxonomic analysis of the soil microbiomes revealed 12 predominant bacterial and archaeal phyla—Proteobacteria, Actinobacteria, Acidobacteria, Chloroflexi, Gemmatimonadetes, Verrucomicrobia, Planctomycetes, Bacteroidetes, Armatimonadetes, Firmicutes, Cyanobacteria, Thaumarchaeota. Some specific phyla have been also found in sub-surface horizons of soils investigated, thus providing additional evidence of the crucial role of gravel pavement in saving the favorable conditions for both soil and microbiome development. Moreover, our study also revealed that some bacterial species might be introduced into Antarctic soils by human activities. We also assessed the effect of different soil parameters on microbial community in the harsh environmental conditions of Eastern Antarctica. pH, carbon and nitrogen, as well as fine earth content, were revealed as the most accurate predictors of soil bacterial community composition.</jats:p>

Diane Esson, Susanna A Wood, Michael A Packer

AMB Express • 2011

<jats:title>Abstract</jats:title> <jats:p>Benthic species of algae and cyanobacteria (i.e., those that grow on surfaces), may provide potential advantages over planktonic species for some commercial-scale biotechnological applications. A multitude of different designs of photobioreactor (PBR) are available for growing planktonic species but to date there has been little research on PBR for benthic algae or cyanobacteria. One notable advantage of some benthic cyanobacterial species is that during their growth cycle they become positively buoyant, detach from the growth surface and form floating mats. This 'self-harvesting' capability could be advantageous in commercial PBRs as it would greatly reduce dewatering costs. In this study we compared the growth rates and efficiency of 'self-harvesting' among three species of benthic cyanobacteria; <jats:italic>Phormidium autumnale</jats:italic>; <jats:italic>Phormidium murrayi</jats:italic> and <jats:italic>Planktothrix sp</jats:italic>.. <jats:italic>Phormidium autumnale</jats:italic> produced the greatest biomass and formed cohesive mats once detached. Using this strain and an optimised MLA media, a variety of geometries of benthic PBRs (bPBRs) were trialed. The geometry and composition of growth surface had a marked effect on cyanobacterial growth. The highest biomass was achieved in a bPBR comprising of a vertical polyethylene bag with loops of silicone tubing to provide additional growth surfaces. The productivity achieved in this bPBR was a similar order of magnitude as planktonic species, with the additional advantage that towards the end of the exponential phase the bulk of the biomass detached forming a dense mat at the surface of the medium.</jats:p>

Francisco J. Arias

Journal of Energy Resources Technology • 2018

<jats:p>The basis of a novel method for seawater desalination is outlined. In this work, pressure-retarded osmosis (PRO) energy is obtained and used posteriorly for the reverse osmosis (RO) process for seawater desalination. Although PRO process coupled with an RO process has been studied in the past, however, in this work, there is a fundamental difference. Instead of bringing river or wastewaters with low salinity to the coast to be mixed with the seawater to run the PRO process, here is the seawater which is deliberately salinized. This technique has one important consequence, namely, that it is no longer required to be in places where rivers or wastewaters flow into the sea. This important difference eliminates this until now somehow paradoxical requirement if one considers that regions needing desalination are generally poor of water resources. On the other hand, it is not a coincidence that regions needing desalination plants are also regions with rich open salt deposits in the neighborhood; high evaporation, high concentration of salt deposits, and the need for freshwater are all of them directly correlated. Therefore, the idea proposed in the paper is consistent with the problem. The high evaporation in the region which is causing the need for desalination also is creating the solution to do this by using the salt deposits created. The economic feasibility of this method is preliminarily assessed in terms of the thermodynamic limits of extractable energy and then with the cost of the salt required to obtain this energy which is compared with the price from electrical grid. It was found that in order to reduce the amount of salt required for the process, and to make the cost of energy competitive, it is necessary to direct the hypersaline draw solution (draw solution) in a cyclic loop and to have the highest possible volume fraction for the nonsalinized solution (feed solution). Additional R&amp;D is required to explore the possibilities of this concept.</jats:p>

Martijn C. Bart, A. de Kluijver, Sean C. S. Hoetjes et al.

Scientific Reports • 2020

Deep-sea sponges create hotspots of biodiversity and biological activity in the otherwise barren deep-sea. However, it remains elusive how sponge hosts and their microbial symbionts acquire and process food in these food-limited environments. Therefore, we traced the processing (i.e. assimilation and respiration) of 13C- and 15N-enriched dissolved organic matter (DOM) and bacteria by three dominant North Atlantic deep-sea sponges: the high microbial abundance (HMA) demosponge Geodia barretti, the low microbial abundance (LMA) demosponge Hymedesmia paupertas, and the LMA hexactinellid Vazella pourtalesii. We also assessed the assimilation of both food sources into sponge- and bacteria-specific phospholipid-derived fatty acid (PLFA) biomarkers. All sponges were capable of assimilating DOM as well as bacteria. However, processing of the two food sources differed considerably between the tested species: the DOM assimilation-to-respiration efficiency was highest for the HMA sponge, yet uptake rates were 4–5 times lower compared to LMA sponges. In contrast, bacteria were assimilated most efficiently and at the highest rate by the hexactinellid compared to the demosponges. Our results indicate that phylogeny and functional traits (e.g., abundance of microbial symbionts, morphology) influence food preferences and diet composition of sponges, which further helps to understand their role as key ecosystem engineers of deep-sea habitats.

Jialin Hou, S. Sievert, Yinzhao Wang et al.

Microbiome • 2020

Background Deep-sea hydrothermal vents are highly productive biodiversity hotspots in the deep ocean supported by chemosynthetic microorganisms. Prominent features of these systems are sulfide chimneys emanating high-temperature hydrothermal fluids. While several studies have investigated the microbial diversity in both active and inactive sulfide chimneys that have been extinct for up to thousands of years, little is known about chimneys that have ceased activity more recently, as well as the microbial succession occurring during the transition from active to inactive chimneys. Results Genome-resolved metagenomics was applied to an active and a recently extinct (~ 7 years) sulfide chimney from the 9–10° N hydrothermal vent field on the East Pacific Rise. Full-length 16S rRNA gene and a total of 173 high-quality metagenome assembled genomes (MAGs) were retrieved for comparative analysis. In the active chimney (L-vent), sulfide- and/or hydrogen-oxidizing Campylobacteria and Aquificae with the potential for denitrification were identified as the dominant community members and primary producers, fixing carbon through the reductive tricarboxylic acid (rTCA) cycle. In contrast, the microbiome of the recently extinct chimney (M-vent) was largely composed of heterotrophs from various bacterial phyla, including Delta -/ Beta -/ Alphaproteobacteria and Bacteroidetes . Gammaproteobacteria were identified as the main primary producers, using the oxidation of metal sulfides and/or iron oxidation coupled to nitrate reduction to fix carbon through the Calvin-Benson-Bassham (CBB) cycle. Further analysis revealed a phylogenetically distinct Nitrospirae cluster that has the potential to oxidize sulfide minerals coupled to oxygen and/or nitrite reduction, as well as for sulfate reduction, and that might serve as an indicator for the early stages of chimneys after venting has ceased. Conclusions This study sheds light on the composition, metabolic functions, and succession of microbial communities inhabiting deep-sea hydrothermal vent sulfide chimneys. Collectively, microbial succession during the life span of a chimney could be described to proceed from a “fluid-shaped” microbial community in newly formed and actively venting chimneys supported by the oxidation of reductants in the hydrothermal fluid to a “mineral-shaped” community supported by the oxidation of minerals after hydrothermal activity has ceased. Remarkably, the transition appears to occur within the first few years, after which the communities stay stable for thousands of years. Video Abstract

Yue Zhang, N. Huang, Minxiao Wang et al.

Frontiers in Microbiology • 2021

Microbial eukaryotes are key components of the marine food web, but their distribution in deep-sea chemosynthetic ecosystems has not been well studied. Here, high-throughput sequencing of the 18S rRNA gene and network analysis were applied to investigate the diversity, distribution and potential relationships between microbial eukaryotes in samples collected from two cold seeps and one trough in the northern South China Sea. SAR (i.e., Stramenopiles, Alveolata, and Rhizaria) was the predominant group in all the samples, and it was highly affiliated to genotypes with potential symbiotic and parasitic strategies identified from other deep-sea extreme environments (e.g., oxygen deficient zones, bathypelagic waters, and hydrothermal vents). Our findings indicated that specialized lineages of deep-sea microbial eukaryotes exist in chemosynthetic cold seeps, where microbial eukaryotes affiliated with parasitic/symbiotic taxa were prevalent in the community. The biogeographic pattern of the total community was best represented by the intermediate operational taxonomic unit (OTU) category, whose relative abundance ranged 0.01–1% within a sample, and the communities of the two cold seeps were distinct from the trough, which suggests that geographical proximity has no critical impact on the distribution of deep-sea microbial eukaryotes. Overall, this study has laid the foundations for future investigations regarding the ecological function and in situ trophic relationships of microbial eukaryotes in deep-sea ecosystems.