Juan Zhang, Zeyu Lin, Junpeng Chen

International Journal of Electric Power and Energy Studies • 2024

The energy sector faces significant challenges related to supply chain traceability, including issues with transparency, data integrity, regulatory compliance, and fraud prevention. Blockchain technology, with its decentralized, transparent, and immutable ledger, offers promising solutions to these challenges. This review explores the application of blockchain technology in enhancing supply chain traceability in the energy sector. It examines the potential benefits in terms of visibility, data integrity, compliance, and sustainability, and discusses real-world applications, challenges, and future directions. Case studies from renewable energy, fossil fuels, and smart grids illustrate blockchain's impact. Despite the promising benefits, technical, regulatory, and implementation challenges remain. Future research and development, along with supportive policy frameworks, are essential for realizing blockchain's full potential in transforming the energy supply chain into a more efficient, transparent, and sustainable system.

Safa Otoum, I. A. Ridhawi, H. Mouftah

IEEE Internet of Things Journal • 2023

Through the digitization of essential functional processes, Industry 4.0 aims to build knowledgeable, networked, and stable value chains. Network trustworthiness is a critical component of network security that is built on positive interactions, guarantees, transparency, and accountability. Blockchain technology has drawn the attention of researchers in various fields of data science as a safe and low-cost platform to track a large number of eventual transactions. Such a technique is adaptable to the renewable energy-trade sector, which suffers from security and trustworthy issues. Having a decentralized energy infrastructure, that is supported by blockchain and artificial intelligence, enables smart and secure microgrid energy trading. The new age of industrial production will be highly versatile in terms of production volume and customization. As such a robust collaboration solution between consumers, businesses, and suppliers must be both secure and sustainable. In this article, we introduce a cooperative and distributed framework that relies on computing, communication, and intelligence capabilities of edge and end devices to enable secure energy trading, remote monitoring, and network trustworthiness. The blockchain and federated learning-enabled solution provide secure energy trading between different critical entities. Such a technique, coupled with 5G and beyond networks, would enable mass surveillance, monitoring, and analysis to occur at the edge. Performance evaluations are conducted to test the effectiveness of the proposed solution in terms of reliability and responsiveness in a vehicular network energy-trade scenario.

Muhammad Faheem, B. Raza, Muhammad Shoaib Bhutta et al.

IET Blockchain • 2024

The rapid and green energy transition is essential to deal with the fast‐growing energy needs in both public and industrial sectors. This has paved the way to integrate distributed renewable energy resources () such as solar, hydro, wind, and geothermal into the power grid (). Wind and solar are free, zero‐carbon emission, and everlasting power sources that contribute 5% and 7% of global electricity generation, respectively. Therefore, the fast, secure, and reliable integration of these green is critical to achieve the instant energy demands. Smart grid due to inherited characteristics such as intelligent sensing, computing, and communication technologies can effectively integrate the . However, the existing smart grid communication architecture faces various cyberattacks, resulting in poor integration, monitoring, and control of . In this respect, blockchain technology can provide fast, secure, and efficient end‐to‐end communication between in the smart grid. In this study, the authors propose a blockchain‐based resilient and secure scheme called for wireless sensor networks ‐based events monitoring and control in . Experimental studies and performance analyses are carried out to predict the efficiency of the proposed scheme by considering numerous standard metrics. The extensive numerical results demonstrated that the proposed scheme is significant in terms of secure, resilient, and reliable information transmission for in .

Andreas Zeiselmair, Bernd Steinkopf, Ulrich Gallersdörfer et al.

Frontiers in Blockchain • 0

<jats:p>The energy system is becoming increasingly decentralized. This development requires integrating and coordinating a rising number of actors and small units in a complex system. Blockchain could provide a base infrastructure for new tools and platforms that address these tasks in various aspects—ranging from dispatch optimization or dynamic load adaption to (local) market mechanisms. Many of these applications are currently in development and subject to research projects. In decentralized energy markets especially, the optimized allocation of energy products demands complex computation. Combining these with distributed ledger technologies leads to bottlenecks and challenges regarding privacy requirements and performance due to limited storage and computational resources. Verifiable computation techniques promise a solution to these issues. This paper presents an overview of verifiable computation technologies, including trusted oracles, zkSNARKs, and multi-party computation. We further analyze their application in blockchain environments with a focus on energy-related applications. Applied to a distinct optimization problem of renewable energy certificates, we have evaluated these solution approaches and finally demonstrate an implementation of a Simplex-Optimization using zkSNARKs as a case study. We conclude with an assessment of the applicability of the described verifiable computation techniques and address limitations for large-scale deployment, followed by an outlook on current development trends.</jats:p>

Anees Fathima, Noor Ayesha, Zahira Tabassum et al.

Blockchain Applications for the Energy and Utilities Industry • 2025

<jats:p>Blockchain has evolved from supporting cryptocurrencies to transforming industries like finance, healthcare, and supply chain management. Emerging trends focus on scalability with Layer 2 solutions, sharding, and cross-chain interoperability. Sustainability efforts include transitioning to Proof-of-Stake, carbon-neutral blockchains, and renewable energy. AI integration enables decentralized models, secure data sharing, and AI-driven smart contracts. Governments explore CBDCs, while privacy technologies like Zero-Knowledge Proofs enhance security. Challenges remain in regulation, security risks, and adoption, but ongoing innovations are driving blockchain's widespread acceptance.</jats:p>

Saad Alateef, Amjad Aldweesh, Mohammad Alauthman et al.

Blockchain Applications for the Energy and Utilities Industry • 2025

<jats:p>This paper proposes a blockchain-based framework to optimize energy supply chain management, delineating its potential to transform energy sourcing, allocation, and consumption processes.The framework elucidates critical components such as decentralized record-keeping, smart contracts for automated transactions, and robust security protocols, thereby ensuring data integrity and resilience against cyberattacks. A prototype system is developed and tested to evaluate performance metrics, including scalability, transaction speed, and energy tracking accuracy.The results highlight the considerable benefits of blockchain, including enhanced transparency, cost efficiency, and improved stakeholder collaboration. Conclusively, the paper identifies current challenges ranging from technical scalability to regulatory hurdles and suggests future directions for augmenting blockchain's impact on energy supply chains, ultimately reinforcing the global transition towards more sustainable energy systems</jats:p>

Enrique Arias, Jose Antonio Mateo, Ali Maqousi et al.

Blockchain Applications for the Energy and Utilities Industry • 2025

<jats:p>Meteorological data is critical not only for climate modeling and weather prediction but also for renewable energy forecasting, demand response, and grid stability in the energy and utilities sector. Conventional data systems rely on centralized architectures vulnerable to single points of failure and poor traceability. This chapter presents a blockchain-based oraculus for storing and retrieving weather observations on an immutable ledger tailored for energy contexts. Specialized oracles, robust consensus, and secure data pipelines ensure tamper-proof storage. Testing confirms reliable retrieval for key stakeholders, including grid operators and regulators. The design supports accurate archiving, real-time ingestion, and flexible access control—vital for planning and operations. By offering a scalable pipeline addressing tampering and integrity, this framework fosters reliable, auditable meteorological systems.</jats:p>

Natalie Colantonio, Younggy Kim

ChemistrySelect • 2016

<jats:title>Abstract</jats:title><jats:p>Advanced treatment, such as tight membrane filtration and ion exchange, can be applied for Pb<jats:sup>2+</jats:sup> removal from wastewater but these methods are expensive with a high demand for electric energy and chemicals. Microbial electrolysis cells (MECs) are an emerging wastewater treatment technology and MECs can remove Pb<jats:sup>2+</jats:sup> by reduction and precipitation at the cathode and biosorption at the anode; however, reduction at the anode has not been reported. We investigated Pb<jats:sup>2+</jats:sup> removal mechanisms using lab‐scale MECs. Using an anion exchange membrane, independent Pb<jats:sup>2+</jats:sup> removal in the anode and cathode chambers was observed at various voltage applications, including open circuit, 0.3 V, 0.6 V, and 0.9 V. A substantial amount of metallic Pb (0. 10 ± 0.02 mg) was found on the graphite fiber anode. Also, the observed anode potential (−0.15 to −0.33 V vs. SHE) indicated sufficient driving force for Pb<jats:sup>2+</jats:sup> reduction at the anode for the Pb<jats:sup>2+</jats:sup> concentration of 0.1 to 2.5 mg L<jats:sup>−1</jats:sup>. Inactivation of exoelectrogens using ethanol resulted in no Pb<jats:sup>2+</jats:sup> removal. The findings show that Pb<jats:sup>2+</jats:sup> removal is achieved by various mechanisms in MECs, including electrodeposition at the anode by exoelectrogens.</jats:p>

Ananda Rao Hari, Krishna P. Katuri, Bruce E. Logan et al.

Scientific Reports • 0

<jats:title>Abstract</jats:title><jats:p>Anode potential has been shown to be a critical factor in the rate of acetate removal in microbial electrolysis cells (MECs), but studies with fermentable substrates and set potentials are lacking. Here, we examined the impact of three different set anode potentials (SAPs; −0.25, 0, and 0.25 V vs. standard hydrogen electrode) on the electrochemical performance, electron flux to various sinks, and anodic microbial community structure in two-chambered MECs fed with propionate. Electrical current (49–71%) and CH<jats:sub>4</jats:sub> (22.9–41%) were the largest electron sinks regardless of the potentials tested. Among the three SAPs tested, 0 V showed the highest electron flux to electrical current (71 ± 5%) and the lowest flux to CH<jats:sub>4</jats:sub> (22.9 ± 1.2%). In contrast, the SAP of −0.25 V had the lowest electron flux to current (49 ± 6%) and the highest flux to CH<jats:sub>4</jats:sub> (41.1 ± 2%). The most dominant genera detected on the anode of all three SAPs based on 16S rRNA gene sequencing were <jats:italic>Geobacter, Smithella</jats:italic> and <jats:italic>Syntrophobacter</jats:italic>, but their relative abundance varied among the tested SAPs. Microbial community analysis implies that complete degradation of propionate in all the tested SAPs was facilitated by syntrophic interactions between fermenters and <jats:italic>Geobacter</jats:italic> at the anode and ferementers and hydrogenotrophic methanogens in suspension.</jats:p>

Abhijeet P. Borole, Alex J. Lewis

Sustainable Energy &amp; Fuels • 0

<p>Proton transfer in microbial electrochemical cells is as important as electron transfer. This study quantifies proton transfer rates in MEC for the first time. Control of flow rate and loading rate allows improvement in proton transfer rates enabling hydrogen productivities &gt;10 L per L per day.</p>

Ahmad Walid Ayoobi, Mehmet Inceoğlu

Energies • 0

<jats:p>The building sector is a major contributor to resource consumption, energy use, and greenhouse gas emissions. Sustainable architecture offers a solution, leveraging Building Energy Modeling (BEM) for early-stage design optimization. This study explores the use of genetic algorithms for optimizing sustainable design strategies holistically. A comprehensive analysis and optimization model was developed using genetic algorithms to individually optimize various sustainable strategies. The optimized strategies were then applied to a pre-existing building in Kabul City, a region facing significant environmental challenges. To enhance accuracy, this study integrated energy simulations with Computational Fluid Dynamics (CFD). This research combines genetic algorithms with energy simulation and CFD analysis to optimize building design for a specific climate. Furthermore, it validates the optimized strategies through a real-world case study building. Optimizing the Window-to-Wall Ratio (WWR) and shading devices based on solar exposure significantly improved the building’s energy performance. South (S)-facing single windows and specific combinations of opposing and adjacent windows emerged as optimal configurations. The strategic optimization of building component materials led to substantial energy savings: a 58.6% reduction in window energy loss, 78.3% in wall loss, and 69.5% in roof loss. Additionally, the optimized pre-existing building achieved a 48.1% reduction in cooling demand, a 97.5% reduction in heating demand, and an overall energy reduction of 84.4%. Improved natural ventilation and controlled solar gain led to a 72.2% reduction in peak-month CO2 emissions. While this study focused on applicable passive design strategies, the integration of advanced technologies like Phase Change Materials (PCMs), kinetic shading devices, and renewable energy systems can further improve building performance and contribute to achieving net-zero buildings.</jats:p>

Leilei Xiao, Yiping Wang, E. Lichtfouse et al.

Frontiers in Microbiology • 2021

Recycling waste into new materials and energy is becoming a major challenge in the context of the future circular economy, calling for advanced methods of waste treatment. For instance, microbially-mediated anaerobic digestion is widely used for conversion of sewage sludge into biomethane, fertilizers and other products, yet the efficiency of microbial digestion is limited by the occurrence of antibiotics in sludges, originating from drug consumption for human and animal health. Here we present antibiotic levels in Chinese wastewater, then we review the effects of antibiotics on hydrolysis, acidogenesis and methanogenesis, with focus on macrolides, tetracyclines, β-lactams and antibiotic mixtures. We detail effects of antibiotics on fermentative bacteria and methanogenic archaea. Most results display adverse effects of antibiotics on anaerobic digestion, yet some antibiotics promote hydrolysis, acidogenesis and methanogenesis.

J. Kelly, Maxwell G. London, A. McCormick et al.

PLOS ONE • 2021

Microplastics are ubiquitous contaminants in aquatic habitats globally, and wastewater treatment plants (WWTPs) are point sources of microplastics. Within aquatic habitats microplastics are colonized by microbial biofilms, which can include pathogenic taxa and taxa associated with plastic breakdown. Microplastics enter WWTPs in sewage and exit in sludge or effluent, but the role that WWTPs play in establishing or modifying microplastic bacterial assemblages is unknown. We analyzed microplastics and associated biofilms in raw sewage, effluent water, and sludge from two WWTPs. Both plants retained >99% of influent microplastics in sludge, and sludge microplastics showed higher bacterial species richness and higher abundance of taxa associated with bioflocculation (e.g. Xanthomonas) than influent microplastics, suggesting that colonization of microplastics within the WWTP may play a role in retention. Microplastics in WWTP effluent included significantly lower abundances of some potentially pathogenic bacterial taxa (e.g. Campylobacteraceae) compared to influent microplastics; however, other potentially pathogenic taxa (e.g. Acinetobacter) remained abundant on effluent microplastics, and several taxa linked to plastic breakdown (e.g. Klebsiella, Pseudomonas, and Sphingomonas) were significantly more abundant on effluent compared to influent microplastics. These results indicate that diverse bacterial assemblages colonize microplastics within sewage and that WWTPs can play a significant role in modifying the microplastic-associated assemblages, which may affect the fate of microplastics within the WWTPs and the environment.

Nathan K. McLain, Melissa Gómez, E. Gachomo

Microbial Ecology • 2022

The practice of using recycled wastewater (RWW) has been successfully adopted to address the growing demand for clean water. However, chemicals of emerging concern (CECs) including pharmaceutical products remain in the RWW even after additional cleaning. When RWW is used to irrigate crops or landscapes, these chemicals can enter these and adjacent environments. Unfortunately, the overall composition and concentrations of CECs found in different RWW sources vary, and even the same source can vary over time. Therefore, we selected one compound that is found frequently and in high concentrations in many RWW sources, acetaminophen (APAP), to use for our study. Using greenhouse grown eggplants treated with APAP concentrations within the ranges found in RWW effluents, we investigated the short-term impacts of APAP on the soil bacterial population under agricultural settings. Using Illumina sequencing-based approaches, we showed that APAP has the potential to cause shifts in the microbial community most likely by positively selecting for bacteria that are capable of metabolizing the breakdown products of APAP such as glycosides and carboxylic acids. Community-level physiological profiles of carbon metabolism were evaluated using Biolog EcoPlate as a proxy for community functions. The Biolog plates indicated that the metabolism of amines, amino acids, carbohydrates, carboxylic acids, and polymers was significantly higher in the presence of APAP. Abundance of microorganisms of importance to plant health and productivity was altered by APAP. Our results indicate that the soil microbial community and functions could be altered by APAP at concentrations found in RWW. Our findings contribute to the knowledge base needed to guide policies regulating RWW reuse in agriculture and also highlight the need to further investigate the effects of CECs found in RWW on soil microbiomes.

L. Carles, S. Wullschleger, A. Joss et al.

• 2022

Wastewater treatment plant effluents can impact microbial communities in receiving streams. However, little is known about the role of microorganisms in wastewater as opposed to other wastewater constituents, such as nutrients and micropollutants. We aimed therefore at determining the impact of wastewater microorganisms on the microbial diversity and function of periphyton, key microbial communities in streams. Periphyton was grown in flow-through channels that were continuously alimented with a mixture of stream water and unfiltered or ultra-filtered wastewater. Impacts were assessed on periphyton biomass, activities and tolerance to micropollutants, as well as on microbial diversity. Our results showed that wastewater microorganisms colonized periphyton and modified its community composition, resulting for instance in an increased abundance of Chloroflexi and a decreased abundance of diatoms and green algae. This led to shifts towards heterotrophy, as suggested by the changes in nutrient stoichiometry and the increased mineralization potential of carbon substrates. An increased tolerance towards micropollutants was only found for periphyton exposed to unfiltered wastewater but not to ultra-filtered wastewater, suggesting that wastewater microorganisms were responsible for this increased tolerance. Overall, our results highlight the need to consider the role of wastewater microorganisms when studying potential impacts of wastewater on the receiving water body. Environmental implication The present study investigates the impact of wastewater microorganisms on periphyton, i.e. communities forming the microbial skin of streambeds. We were able to disentangle specific effects of wastewater microorganisms in the context of the complex wastewater matrix. Indeed, wastewater microorganisms induced strong changes in periphyton community composition and function, suggesting the need to consider wastewater microbial communities as a stressor per se, similarly to, e.g., nutrients and micropollutants. Moreover, since periphyton is at the basis of the food web in streams, these changes may have consequences for higher trophic levels.

Shiwangi Kesarwani, Diksha Panwar, J. Mal et al.

Fermentation • 2022

The availability of clean water and the depletion of non-renewable resources provide challenges to modern society. The widespread use of conventional wastewater treatment necessitates significant financial and energy expenditure. Constructed Wetland Microbial Fuel Cells (CW-MFCs), a more recent alternative technology that incorporates a Microbial Fuel Cell (MFC) inside a Constructed Wetland (CW), can alleviate these problems. By utilizing a CW’s inherent redox gradient, MFC can produce electricity while also improving a CW’s capacity for wastewater treatment. Electroactive bacteria in the anaerobic zone oxidize the organic contaminants in the wastewater, releasing electrons and protons in the process. Through an external circuit, these electrons travel to the cathode and produce electricity. Researchers have demonstrated the potential of CW-MFC technology in harnessing bio-electricity from wastewater while achieving pollutant removal at the lab and pilot scales, using both domestic and industrial wastewater. However, several limitations, such as inadequate removal of nitrogen, phosphates, and toxic organic/inorganic pollutants, limits its applicability on a large scale. In addition, the whole system must be well optimized to achieve effective wastewater treatment along with energy, as the ecosystem of the CW-MFC is large, and has diverse biotic and abiotic components which interact with each other in a dynamic manner. Therefore, by modifying important components and optimizing various influencing factors, the performance of this hybrid system in terms of wastewater treatment and power generation can be improved, making CW-MFCs a cost-effective, cleaner, and more sustainable approach for wastewater treatment that can be used in real-world applications in the future.

S. Malik, Archna Dhasmana, S. Preetam et al.

Nanomaterials • 2022

Water scarcity due to contamination of water resources with different inorganic and organic contaminants is one of the foremost global concerns. It is due to rapid industrialization, fast urbanization, and the low efficiency of traditional wastewater treatment strategies. Conventional water treatment strategies, including chemical precipitation, membrane filtration, coagulation, ion exchange, solvent extraction, adsorption, and photolysis, are based on adopting various nanomaterials (NMs) with a high surface area, including carbon NMs, polymers, metals-based, and metal oxides. However, significant bottlenecks are toxicity, cost, secondary contamination, size and space constraints, energy efficiency, prolonged time consumption, output efficiency, and scalability. On the contrary, green NMs fabricated using microorganisms emerge as cost-effective, eco-friendly, sustainable, safe, and efficient substitutes for these traditional strategies. This review summarizes the state-of-the-art microbial-assisted green NMs and strategies including microbial cells, magnetotactic bacteria (MTB), bio-augmentation and integrated bioreactors for removing an extensive range of water contaminants addressing the challenges associated with traditional strategies. Furthermore, a comparative analysis of the efficacies of microbe-assisted green NM-based water remediation strategy with the traditional practices in light of crucial factors like reusability, regeneration, removal efficiency, and adsorption capacity has been presented. The associated challenges, their alternate solutions, and the cutting-edge prospects of microbial-assisted green nanobiotechnology with the integration of advanced tools including internet-of-nano-things, cloud computing, and artificial intelligence have been discussed. This review opens a new window to assist future research dedicated to sustainable and green nanobiotechnology-based strategies for environmental remediation applications.

G. Tsekouras, Panagiota M. Deligianni, F. Kanellos et al.

Frontiers in Energy Research • 2022

Microbial fuel cells (MFCs) have undergone great technological development in the last 20 years, but very little has been done to commercialize them. The simultaneous power production and wastewater treatment are features those greatly increase the interest in the use of MFCs. This kind of distributed power generation is renewable and friendly and can be easily integrated into a smart grid. However, there are some key issues with their commercialization: high construction costs, difficulty in developing high power structures, MFC lifespan, and maintaining a high level of efficiency. The objective of this article is to explore the possibilities of using MFCs in urban wastewater not only regarding the technical criteria of their application, but also mainly from an economic point of view, to determine the conditions through which the viability of the investment is ensured and the possibilities of their integration in a smart grid are identified. Initially, this article explores the implementation/configuration of a power plant with MFCs within an urban wastewater treatment plant on a theoretical basis. In addition, based on the corresponding physical quantities for urban wastewater treatment, the construction and operational costs are determined and the viability of the investment is examined based on classic economic criteria such as net present value, benefit–cost ratio, internal rate of return, and discounted payback period. Furthermore, sensitivity analysis is carried out, concerning both technical parameters, such as the percentage of organic matter removal, power density, sewage residence time, MFC efficiency, etc., and economical parameters, such as the reduction of construction costs due to change of materials, change of interest rate, and lifetime. The advantages and disadvantages of their use in smart grids is also analyzed. The results show that the use of MFCs for power generation cannot be utopian as long as they are integrated into the structure of a central wastewater treatment plant on the condition that the scale-up technical issues of MFCs are successfully addressed.

Yamini Koul, Viralkunvar Devda, Sunita Varjani et al.

Bioengineered • 2022

ABSTRACT Wastewater is one of the most common by-products of almost every industrial process. Treatment of wastewater alone, before disposal, necessitates an excess of energy. Environmental concerns over the use of fossil fuels as a source of energy have prompted a surge in demand for alternative energy sources and the development of sophisticated procedures to extract energy from unconventional sources. Treatment of municipal and industrial wastewater alone accounts for about 3% of global electricity use while the amount of energy embedded in the waste is at least 2–4 times greater than the energy required to treat the same effluent. The microbial electrolysis cell (MEC) is one of the most efficient technologies for waste-to-product conversion that uses electrochemically active bacteria to convert organic matter into hydrogen or a variety of by-products without polluting the environment. This paper highlights existing obstacles and future potential in the integration of Microbial Electrolysis Cell with other processes like anaerobic digestion coupled system, anaerobic membrane bioreactor and thermoelectric micro converter. Graphical abstract_R1

Shahjahon Begmatov, A. Dorofeev, V. Kadnikov et al.

Scientific Reports • 2022

Microbial communities in wastewater treatment plants (WWTPs) play a key role in water purification. Microbial communities of activated sludge (AS) vary extensively based on plant operating technology, influent characteristics and WWTP capacity. In this study we performed 16S rRNA gene profiling of AS at nine large-scale WWTPs responsible for the treatment of municipal sewage from the city of Moscow, Russia. Two plants employed conventional aerobic process, one plant—nitrification/denitrification technology, and six plants were operated with the University of Cape Town (UCT) anaerobic/anoxic/oxic process. Microbial communities were impacted by the technology and dominated by the Proteobacteria, Bacteroidota and Actinobacteriota. WWTPs employing the UCT process enabled efficient removal of not only organic matter, but also nitrogen and phosphorus, consistently with the high content of ammonia-oxidizing Nitrosomonas sp. and phosphate-accumulating bacteria. The latter group was represented by Candidatus Accumulibacter, Tetrasphaera sp. and denitrifiers. Co-occurrence network analysis provided information on key hub microorganisms in AS, which may be targeted for manipulating the AS stability and performance. Comparison of AS communities from WWTPs in Moscow and worldwide revealed that Moscow samples clustered together indicating that influent characteristics, related to social, cultural and environmental factors, could be more important than a plant operating technology.

Stephanie L. Rich, Michael T. Zumstein, D. Helbling

Environmental Science &amp; Technology • 2021

The goal of this research was to identify functional groups that determine rates of micropollutant (MP) biotransformations performed by wastewater microbial communities. To meet this goal, we performed a series of incubation experiments seeded with four independent wastewater microbial communities and spiked them with a mixture of 40 structurally diverse MPs. We collected samples over time and used high-resolution mass spectrometry to estimate biotransformation rate constants for each MP in each experiment and to propose structures of 46 biotransformation products. We then developed random forest models to classify the biotransformation rate constants based on the presence of specific functional groups or observed biotransformations. We extracted classification importance metrics from each random forest model and compared them across wastewater microbial communities. Our analysis revealed 30 functional groups that we define as either biotransformation promoters, biotransformation inhibitors, structural features that can be biotransformed based on uncharacterized features of the wastewater microbial community, or structural features that are not rate-determining. Our experimental data and analysis provide novel insights into MP biotransformations that can be used to more accurately predict MP biotransformations or to inform the design of new chemical products that may be more readily biodegradable during wastewater treatment.

Yulin Zhang, Yulin Wang, M. Tang et al.

Microbiome • 2023

Background Wastewater treatment plants (WWTPs) are one of the largest biotechnology applications in the world and are of critical importance to modern urban societies. An accurate evaluation of the microbial dark matter (MDM, microorganisms whose genomes remain uncharacterized) proportions in WWTPs is of great value, while there is no such research yet. This study conducted a global meta-analysis of MDM in WWTPs with 317,542 prokaryotic genomes from the Genome Taxonomy Database and proposed a “wanted list” for priority targets in further investigations of activated sludge. Results Compared with the Earth Microbiome Project data, WWTPs had relatively lower genome-sequenced proportions of prokaryotes than other ecosystems, such as the animal related environments. Analysis showed that the median proportions of the genome-sequenced cells and taxa (100% identity and 100% coverage in 16S rRNA gene region) in WWTPs reached 56.3% and 34.5% for activated sludge, 48.6% and 28.5% for aerobic biofilm, and 48.3% and 28.5% for anaerobic digestion sludge, respectively. This result meant MDM had high proportions in WWTPs. Besides, all of the samples were occupied by a few predominant taxa, and the majority of the sequenced genomes were from pure cultures. The global-scale “wanted list” for activated sludge contained four phyla that have few representatives and 71 operational taxonomic units with the majority of them having no genome or isolate yet. Finally, several genome mining methods were verified to successfully recover genomes from activated sludge such as hybrid assembly of the second- and third-generation sequencing. Conclusions This work elucidated the proportion of MDM in WWTPs, defined the “wanted list” of activated sludge for future investigations, and certified potential genome recovery methods. The proposed methodology of this study can be applied to other ecosystems and improve understanding of ecosystem structure across diverse habitats. Video Abstract

Zicheng Su, Tao Liu, Jianhua Guo et al.

Environmental Science &amp; Technology • 2023

Microbial nitrite oxidation is the primary pathway that generates nitrate in wastewater treatment systems and can be performed by a variety of microbes: namely, nitrite-oxidizing bacteria (NOB). Since NOB were first isolated 130 years ago, the understanding of the phylogenetical and physiological diversities of NOB has been gradually deepened. In recent endeavors of advanced biological nitrogen removal, NOB have been more considered as a troublesome disruptor, and strategies on NOB suppression often fail in practice after long-term operation due to the growth of specific NOB that are able to adapt to even harsh conditions. In line with a review of the history of currently known NOB genera, a phylogenetic tree is constructed to exhibit a wide range of NOB in different phyla. In addition, the growth behavior and metabolic performance of different NOB strains are summarized. These specific features of various NOB (e.g., high oxygen affinity of Nitrospira, tolerance to chemical inhibitors of Nitrobacter and Candidatus Nitrotoga, and preference to high temperature of Nitrolancea) highlight the differentiation of the NOB ecological niche in biological nitrogen processes and potentially support their adaptation to different suppression strategies (e.g., low dissolved oxygen, chemical treatment, and high temperature). This review implicates the acquired physiological characteristics of NOB to their emergence from a genomic and ecological perspective and emphasizes the importance of understanding physiological characterization and genomic information in future wastewater treatment studies.

Klaudia Kwiatkowska, Paulina Ormaniec

Microbial Ecology • 2024

Despite some effectiveness of wastewater treatment processes, microplastics accumulate in sewage sludge and their further use may contribute to the release of plastic microplastics into the environment. There is an urgent need to reduce the amount of microplastics in sewage sludge. Plastic particles serve as solid substrates for various microorganisms, promoting the formation of microbial biofilms with different metabolic activities. The biofilm environment associated with microplastics will determine the efficiency of treatment processes, especially biological methods, and the mechanisms of organic compound conversion. A significant source of microplastics is the land application of sewage sludge from wastewater treatment plants. The detrimental impact of microplastics affects soil enzymatic activity, soil microorganisms, flora, fauna, and plant production. This review article summarizes the development of research related to microplastics and discusses the issue of microplastic introduction from sewage sludge. Given that microplastics can contain complex composite polymers and form a plastisphere, further research is needed to understand their potential environmental impact, pathogenicity, and the characteristics of biofilms in wastewater treatment systems. The article also discusses the physicochemical properties of microplastics in wastewater treatment plants and their role in biofilm formation. Then, the article explained the impact of these properties on the possibility of the formation of biofilms on their surface due to the peculiar structure of microorganisms and also characterized what factors enable the formation of specific plastisphere in wastewater treatment plants. It highlights the urgent need to understand the basic information about microplastics to assess environmental toxicity more rationally, enabling better pollution control and the development of regulatory standards to manage microplastics entering the environment.

Thamali Kariyawasam, Christian Helvig, Martin Petkovich et al.

Microbial Biotechnology • 2024

<jats:title>Abstract</jats:title><jats:p>Pharmaceuticals are of increasing environmental concern as they emerge and accumulate in surface‐ and groundwater systems around the world, endangering the overall health of aquatic ecosystems. Municipal wastewater discharge is a significant vector for pharmaceuticals and their metabolites to enter surface waters as humans incompletely absorb prescription drugs and excrete up to 50% into wastewater, which are subsequently incompletely removed during wastewater treatment. Microalgae present a promising target for improving wastewater treatment due to their ability to remove some pollutants efficiently. However, their inherent metabolic pathways limit their capacity to degrade more recalcitrant organic compounds such as pharmaceuticals. The human liver employs enzymes to break down and absorb drugs, and these enzymes are extensively researched during drug development, meaning the cytochrome P450 enzymes responsible for metabolizing each approved drug are well studied. Thus, unlocking or increasing cytochrome P450 expression in endogenous wastewater microalgae could be a cost‐effective strategy to reduce pharmaceutical loads in effluents. Here, we discuss the challenges and opportunities associated with introducing cytochrome P450 enzymes into microalgae. We anticipate that cytochrome P450‐engineered microalgae can serve as a new drug removal method and a sustainable solution that can upgrade wastewater treatment facilities to function as “mega livers”.</jats:p>

Akash Tripathi, Shraddha Yadav, Santosh Kumar et al.

Resource Recovery from Industrial Wastewater through Microbial Electrochemical Technologies • 2024

<jats:p>A microbial electrolysis cell (MEC) has been developed as an effective technology for the microbial conversion of organic matter contained in industrial wastes and sludge into valuable products such as biogas or biochemicals. Exploiting industrial wastewater to produce biogas or chemicals will improve circular economy and concurrently attract industries to pre-treat their wastewater before discharging. However, the products of an MEC such as CH4, H2, H2O2, and other chemicals are not thermodynamically favourable reactions; hence, an external voltage is required to support these reduction reactions. In this regard, optimizing MEC's different operational parameters and reactor configuration is obligatory to reduce the system's external energy demand, and associated energy loss and simultaneously achieving high conversion efficiency. The critical aspects of this chapter are discussing the basic concept of an MEC and its configurations with a detailed description of the thermodynamic aspect of the process. Furthermore, the description of industrial wastewater characteristics provides a better assessment regarding adopting this technology in industries. Overall, this chapter highlights the significance of MECs as a potential solution for transforming industrial wastewater and sludge into valuable resources, while encouraging environmentally friendly and sustainable practices.</jats:p>

Aritro Banerjee, Rajnish Calay, Mohamad Mustafa

Energies • 0

<jats:p>Microbial Fuel Cell (MFC) is a bio-electrochemical system that generates electricity by anaerobic oxidation of substrates. An anode is the most critical component because the primary conversion of wastewater into electrons and protons takes place on the surface of the anode, where a biofilm is formed. This paper describes the essential properties of the anode and classifies its types according to the material used to make it. Anode material is responsible for the flow of electrons generated by the microorganism; hence biocompatibility and conductivity can considered to be the two most important properties. In this paper, the various modification strategies to improve the performance of anodes of MFC are explained through the review of researchers’ published work in this field. The shape and size of the anode turned out to be very significant as the microbial growth depends on the available surface area. The attachment of biofilm on the surface of an anode largely depends on the interfacial surface chemistry. Methods for improving MFC performance by altering the anode material, architecture, biocompatibility, and longevity are discussed with a future perspective giving special importance to the cost.</jats:p>

Xiaoniu Yu, Xiaohua Pan

Marine Georesources &amp; Geotechnology • 2022

Abstract Seawater based bio-cementation through microbially-induced carbonate precipitation was proposed for the calcareous sand improvement in marine environment. The method used seawater instead of traditional fresh water to culture urease producing-bacteria (UPB) and prepare cementation solution (CS) for the bio-cement. A series of comparative bio-treatment tests using seawater based bio-cementation and traditional bio-cementation methods on three types of soil were conducted. Experimental results indicate that seawater based bio-cementation method has the ability to improve soil physico-mechanical properties, and performed better than traditional bio-cementation method. The dominant reason can be explained as that the mixture of the productions of calcite, monohydrocalcite and calcite magnesium produced during seawater based bio-cementation process have better cementation ability than the mixture of the productions of calcite and vaterite produced during bio-cementation process. UCS of coarse Ottawa sand blocks are smaller than that of medium Ottawa sand blocks is because the specific surface area of fine sand is higher and larger number of effective bondings can be formed. UCS of calcareous sand blocks are smaller than those of coarse Ottawa sand blocks can be attributed to the fact that calcareous sand has higher porosity and rougher surface, resulting in more carbonate crystals being precipitated on un-connected locations.

Lu Wang, Jinge Yao, Haikuo Zhang et al.

Frontiers in Marine Science • 2023

The shipping industry plays a vital role in the world trading system and in maintaining the stability of global supply chains. However, we cannot ignore the damage it brings to the marine environment. With a focus on protecting the marine environment, the sustainable development of shipping companies has also drawn growing attention. This study examines the sustainable shipping management practice system and develops a comprehensive framework to evaluate the significance of influencing elements and prioritizes those factors. This paper adopts a fuzzy analytic hierarchy process method. It establishes a total of 11 sub-index systems from three aspects: the external policy pressure of shipping companies, the ecological design of shipping services, and the cross-functional green management within shipping companies. We used the fuzzy analytic hierarchy process (FAHP) to analyze data collected from 37 experts in the Chinese shipping industry. The findings show that external policy pressure is the most critical factor influencing sustainable shipping management, followed by eco-design and cross-functional green management. These factors have a big impact and provide management references for shipping company managers and policymakers. They also give the government a company perspective when creating pertinent regulations.

C. Cruz Viggi, E. Presta, M. Bellagamba et al.

Frontiers in Microbiology • 2015

This study presents the proof-of-concept of the “Oil-Spill Snorkel”: a novel bioelectrochemical approach to stimulate the oxidative biodegradation of petroleum hydrocarbons in sediments. The “Oil-Spill Snorkel” consists of a single conductive material (the snorkel) positioned suitably to create an electrochemical connection between the anoxic zone (the contaminated sediment) and the oxic zone (the overlying O2-containing water). The segment of the electrode buried within the sediment plays a role of anode, accepting electrons deriving from the oxidation of contaminants. Electrons flow through the snorkel up to the part exposed to the aerobic environment (the cathode), where they reduce oxygen to form water. Here we report the results of lab-scale microcosms setup with marine sediments and spiked with crude oil. Microcosms containing one or three graphite snorkels and controls (snorkel-free and autoclaved) were monitored for over 400 days. Collectively, the results of this study confirmed that the snorkels accelerate oxidative reactions taking place within the sediment, as documented by a significant 1.7-fold increase (p = 0.023, two-tailed t-test) in the cumulative oxygen uptake and 1.4-fold increase (p = 0.040) in the cumulative CO2 evolution in the microcosms containing three snorkels compared to snorkel-free controls. Accordingly, the initial rate of total petroleum hydrocarbons (TPH) degradation was also substantially enhanced. Indeed, while after 200 days of incubation a negligible degradation of TPH was noticed in snorkel-free controls, a significant reduction of 12 ± 1% (p = 0.004) and 21 ± 1% (p = 0.001) was observed in microcosms containing one and three snorkels, respectively. Although, the “Oil-Spill Snorkel” potentially represents a groundbreaking alternative to more expensive remediation options, further research efforts are needed to clarify factors and conditions affecting the snorkel-driven biodegradation processes and to identify suitable configurations for field applications.

E. Gambino, K. Chandrasekhar, R. A. Nastro

Environmental Science and Pollution Research • 2021

Marine pollution is becoming more and more serious, especially in coastal areas. Because of the sequestration and consequent accumulation of pollutants in sediments (mainly organic compounds and heavy metals), marine environment restoration cannot exempt from effective remediation of sediments themselves. It has been well proven that, after entering into the seawater, these pollutants are biotransformed into their metabolites, which may be more toxic than their parent molecules. Based on their bioavailability and toxic nature, these compounds may accumulate into the living cells of marine organisms. Pollutants bioaccumulation and biomagnification along the marine food chain lead to seafood contamination and human health hazards. Nowadays, different technologies are available for sediment remediation, such as physicochemical, biological, and bioelectrochemical processes. This paper gives an overview of the most recent techniques for marine sediment remediation while presenting sediment-based microbial fuel cells (SMFCs). We discuss the issues, the progress, and future perspectives of SMFC application to the removal of hydrocarbons and metals in the marine environment with concurrent energy production. We give an insight into the possible mechanisms leading to sediment remediation, SMFC energy balance, and future exploitation.

Haiman Wang, Yeting Zhang, Guiqiang Wang

Advances in Transdisciplinary Engineering • 2022

<jats:p>Continuous stirred bioelectrochemical system (CSBES), consisting of anaerobic digestion reaction zone (ADRZ) and bioelectrochemical reaction zone (BERZ), was constructed to investigate the ammonia inhibitory effects on the performance of electricity generation and wastewater treatment. Continuous experiments were conducted with ammonia concentration ranging from 300 mg/L to 1200 mg/L. As the ammonia concentration increasing from 300 mg/L to 900 mg/L, both of the maximum power densities and the COD removal increased. When the ammonia concentration reached to 1200 mg/L, the maximum power densities of the four cells decreased by 55.7%, 58.9%, 58.0% and 60.6% in comparison with that under ammonia concentration of 900 mg/L. The COD removal reduced to 71.2 ± 1.4%, leading to COD concentration in the effluent increased to 1758 ± 93 mg/L. Electrochemical measurements revealed that the deterioration of anode performance caused the reduction of power generation. The conductivity control experiment showed that the toxic effects of high ammonia concentration on exoelectrogens caused performance deterioration of the CSBES. The threshold ammonia concentration that triggered the inhibition effect on exoelectrogens in CSBES was 1200 mg/L, and the anaerobic consortium in ADRZ could tolerant to higher ammonia concentration than the exoelectrogens in BERZ.</jats:p>

Youzhao Wang, Yuan Pan, Xianjin Li et al.

Water Environment Research • 2019

<jats:title>Abstract</jats:title><jats:sec><jats:label/><jats:p>Excess sludge contains a large amount of organic matter, most of which is present in the form of bacteria and extracellular polymeric substances. In this study, a photosynthetic bioelectrochemical system (<jats:styled-content style="fixed-case">BES</jats:styled-content>) combined with ultrasonic treatment (<jats:styled-content style="fixed-case">UT</jats:styled-content>) was investigated to mineralize sludge. The sludge was disintegrated by the <jats:styled-content style="fixed-case">UT</jats:styled-content>, and the supernatant separated from the treated sludge was further degraded through a bioelectrochemical system containing photosynthetic bacteria (<jats:styled-content style="fixed-case">PSB</jats:styled-content>‐<jats:styled-content style="fixed-case">BES</jats:styled-content>). The <jats:styled-content style="fixed-case">UT</jats:styled-content> efficiency was enhanced by supernatant separation. The <jats:styled-content style="fixed-case">PSB</jats:styled-content>‐<jats:styled-content style="fixed-case">BES</jats:styled-content> method effectively improved the degradation of the soluble chemical oxygen demand (<jats:styled-content style="fixed-case">SCOD</jats:styled-content>) from the supernatant. The <jats:styled-content style="fixed-case">SCOD</jats:styled-content> and protein removal were increased 1.4 and 1.5 times, respectively, compared to <jats:styled-content style="fixed-case">BES</jats:styled-content> without <jats:styled-content style="fixed-case">PSB</jats:styled-content>. In addition, the effects of several key operating factors including illumination, voltage, and temperature were systematically investigated. This study provides a basis for further development of sludge mineralization processes.</jats:p></jats:sec><jats:sec><jats:title>Practitioner points</jats:title><jats:p> <jats:list list-type="bullet"> <jats:list-item><jats:p>The sludge was disintegrated by the ultrasound treatment.</jats:p></jats:list-item> <jats:list-item><jats:p>The supernatant separated from treated sludge was further degraded by a bioelectrochemical system combined with photosynthetic bacteria.</jats:p></jats:list-item> <jats:list-item><jats:p>The ultrasonic treatment efficiency was enhanced by supernatant separation.</jats:p></jats:list-item> <jats:list-item><jats:p>The PSB‐BES method effectively improved the soluble chemical oxygen demand (SCOD) degradation from the supernatant.</jats:p></jats:list-item> <jats:list-item><jats:p>The effects of several key operating factors including light (dark–photo), voltage, and temperature were systematically investigated.</jats:p></jats:list-item> </jats:list> </jats:p></jats:sec>

Long Chen, Yanli Guo, Shaohui Zhang et al.

Water Environment Research • 2023

<jats:title>Abstract</jats:title><jats:sec><jats:label/><jats:p>Bioelectrochemical system is a novel method for controlling down nitrate pollution, yet the feasibility of using methane as the electron donors for denitrification in this system remains unknown. In this study, using the effluent from mother BESs as inocula, a denitrifying anaerobic methane oxidation bioelectrochemical system was successfully started up in 92 days. When operated with 50 mmol/L phosphate buffer solution at pH 7 and 30°C, the maximum methane consumption, nitrate, and total nitrogen removal load reached 0.23 ± 0.01 mmol/d, 551.0 ± 22.1 mg N/m<jats:sup>3</jats:sup>/d, and 64.0 ± 18.8 mg N/m<jats:sup>3</jats:sup>/d, respectively. Meanwhile, the peak voltage of 93 ± 4 mV, the anodic coulombic efficiency of 6.99 ± 0.20%, and the maximum power density of 219.86 mW/m<jats:sup>3</jats:sup> were obtained. The metagenomics profiles revealed that the dominant denitrifying bacteria in the cathodic chamber reduced most nitrate to nitrite through denitrification and assimilatory reduction. In the anodic chamber, various archaea including methanotrophs and methanogens converted methane via reverse methanogenesis to form formate (or H<jats:sub>2</jats:sub>), acetate, and methyl compounds, which were than utilized by electroactive bacteria to generate electricity.</jats:p></jats:sec><jats:sec><jats:title>Practitioner Points</jats:title><jats:p><jats:list list-type="bullet"> <jats:list-item><jats:p>A denitrifying anaerobic methane oxidation BES was successfully started up in 92 d.</jats:p></jats:list-item> <jats:list-item><jats:p>Simultaneous removal of methane and nitrate was achieved in the DAMO‐BES.</jats:p></jats:list-item> <jats:list-item><jats:p>Functional genes related to AMO and denitrification were detected in the DAMO‐BES.</jats:p></jats:list-item> <jats:list-item><jats:p>Methylocystis can mediate AMO in the anode and denitrification in the cathode.</jats:p></jats:list-item> </jats:list></jats:p></jats:sec>

C. McCann, Matthew John Wade, N. Gray et al.

Frontiers in Microbiology • 2016

The High Arctic is dominated by polar desert habitats whose microbial communities are poorly understood. In this study, we used next generation sequencing to describe the α- and β-diversity of microbial communities in polar desert soils from the Kongsfjorden region of Svalbard. Ten phyla dominated the soils and accounted for 95% of all sequences, with the Proteobacteria, Actinobacteria, and Chloroflexi being the major lineages. In contrast to previous investigations of Arctic soils, relative Acidobacterial abundances were found to be very low as were the Archaea throughout the Kongsfjorden polar desert landscape. Lower Acidobacterial abundances were attributed to characteristic circumneutral soil pHs in this region, which has resulted from the weathering of underlying carbonate bedrock. In addition, we compared previously measured geochemical conditions as possible controls on soil microbial communities. Phosphorus, pH, nitrogen, and calcium levels all significantly correlated with β-diversity, indicating landscape-scale lithological control of available nutrients, which in turn, significantly influenced soil community composition. In addition, soil phosphorus and pH significantly correlated with α-diversity, particularly with the Shannon diversity and Chao 1 richness indices.

A. Šťovíček, Minsu Kim, D. Or et al.

Scientific Reports • 2017

Life in desert soil is marked by episodic pulses of water and nutrients followed by long periods of drought. While the desert flora and fauna flourish after rainfall the response of soil microorganisms remains unclear and understudied. We provide the first systematic study of the role of soil aqueous habitat dynamics in shaping microbial community composition and diversity. Detailed monitoring of natural microbial communities after a rainfall event revealed a remarkable decrease in diversity and a significant transition in community composition that were gradually restored to pre-rainfall values during soil desiccation. Modelling results suggest a critical role for the fragmented aqueous habitat in maintaining microbial diversity under dry soil conditions and diversity loss with wetting events that increase connectivity among habitats. This interdisciplinary study provides new insights into wetting and drying processes that promote and restore the unparalleled microbial diversity found in soil.

R. Marasco, Maria J Mosqueira, M. Fusi et al.

Microbiome • 2018

The rhizosheath-root system is an adaptive trait of sandy-desert speargrasses in response to unfavourable moisture and nutritional conditions. Under the deserts’ polyextreme conditions, plants interact with edaphic microorganisms that positively affect their fitness and resistance. However, the trophic simplicity and environmental harshness of desert ecosystems have previously been shown to strongly influence soil microbial community assembly. We hypothesize that sand-driven ecological filtering constrains the microbial recruitment processes in the speargrass rhizosheath-root niche, prevailing over the plant-induced selection. Bacterial and fungal communities from the rhizosheath-root compartments (endosphere root tissues, rhizosheath and rhizosphere) of three Namib Desert speargrass species (Stipagrostis sabulicola, S. seelyae and Cladoraphis spinosa) along with bulk sand have been studied to test our hypothesis. To minimize the variability determined by edaphic and climatic factors, plants living in a single dune were studied. We assessed the role of plant species vs the sandy substrate on the recruitment and selection, phylogenetic diversity and co-occurrence microbial networks of the rhizosheath-root system microbial communities. Microorganisms associated with the speargrass rhizosheath-root system were recruited from the surrounding bulk sand population and were significantly enriched in the rhizosheath compartments (105 and 104 of bacterial 16S rRNA and fungal ITS copies per gram of sand to up to 108 and 107 copies per gram, respectively). Furthermore, each rhizosheath-root system compartment hosted a specific microbial community demonstrating strong niche-partitioning. The rhizosheath-root systems of the three speargrass species studied were dominated by desert-adapted Actinobacteria and Alphaproteobacteria (e.g. Lechevalieria, Streptomyces and Microvirga) as well as saprophytic Ascomycota fungi (e.g. Curvularia, Aspergillus and Thielavia). Our results clearly showed a random phylogenetic turnover of rhizosheath-root system associated microbial communities, independent of the plant species, where stochastic factors drive neutral assembly. Co-occurrence network analyses also indicated that the bacterial and fungal community members of the rhizosheath-root systems established a higher number of interactions than those in the barren bulk sand, suggesting that the former are more stable and functional than the latter. Our study demonstrates that the rhizosheath-root system microbial communities of desert dune speargrasses are stochastically assembled and host-independent. This finding supports the concept that the selection determined by the desert sand prevails over that imposed by the genotype of the different plant species.

G. Uritskiy, A. Munn, Micah Dailey et al.

Frontiers in Microbiology • 2020

Spatial heterogeneity in microbial communities is observed in all natural ecosystems and can stem from both adaptations to local environmental conditions as well as stochastic processes. Extremophile microbial communities inhabiting evaporitic halite nodules (salt rocks) in the Atacama Desert, Chile, are a good model ecosystem for investigating factors leading to microbiome heterogeneity, due to their diverse taxonomic composition and the spatial segregation of individual nodules. We investigated the abiotic factors governing microbiome composition across different spatial scales, allowing for insight into the factors that govern halite colonization from regional desert-wide scales to micro-scales within individual nodules. We found that water availability and community drift account for microbiome assembly differently at different distance scales, with higher rates of cell dispersion at the smaller scales resulting in a more homogenous composition. This trend likely applies to other endoliths, and to non-desert communities, where dispersion between communities is limited. At the intra-nodule scales, a light availability gradient was most important in determining the distribution of microbial taxa despite intermixing by water displacement via capillary action.

D. Schulze‐Makuch, D. Wagner, S. Kounaves et al.

Proceedings of the National Academy of Sciences • 2018

Significance It has remained an unresolved question whether microorganisms recovered from the most arid environments on Earth are thriving under such extreme conditions or are just dead or dying vestiges of viable cells fortuitously deposited by atmospheric processes. Based on multiple lines of evidence, we show that indigenous microbial communities are present and temporally active even in the hyperarid soils of the Atacama Desert (Chile). Following extremely rare precipitation events in the driest parts of this desert, where rainfall often occurs only once per decade, we were able to detect episodic incidences of biological activity. Our findings expand the range of hyperarid environments temporarily habitable for terrestrial life, which by extension also applies to other planetary bodies like Mars. Traces of life are nearly ubiquitous on Earth. However, a central unresolved question is whether these traces always indicate an active microbial community or whether, in extreme environments, such as hyperarid deserts, they instead reflect just dormant or dead cells. Although microbial biomass and diversity decrease with increasing aridity in the Atacama Desert, we provide multiple lines of evidence for the presence of an at times metabolically active, microbial community in one of the driest places on Earth. We base this observation on four major lines of evidence: (i) a physico-chemical characterization of the soil habitability after an exceptional rain event, (ii) identified biomolecules indicative of potentially active cells [e.g., presence of ATP, phospholipid fatty acids (PLFAs), metabolites, and enzymatic activity], (iii) measurements of in situ replication rates of genomes of uncultivated bacteria reconstructed from selected samples, and (iv) microbial community patterns specific to soil parameters and depths. We infer that the microbial populations have undergone selection and adaptation in response to their specific soil microenvironment and in particular to the degree of aridity. Collectively, our results highlight that even the hyperarid Atacama Desert can provide a habitable environment for microorganisms that allows them to become metabolically active following an episodic increase in moisture and that once it decreases, so does the activity of the microbiota. These results have implications for the prospect of life on other planets such as Mars, which has transitioned from an earlier wetter environment to today’s extreme hyperaridity.

Jill A. Sohm, T. D. Niederberger, A. Parker et al.

Frontiers in Microbiology • 2020

Cyanobacterial mats in the Antarctic Dry Valleys are photosynthetic microbial ecosystems living at the extreme of conditions on Earth with respect to temperature, light, water and nutrient availability. They are metabolically active for about 8 weeks during the austral summer when temperatures briefly rise above freezing and glacial and lake melt waters are available. There is much to learn about the biogeochemical impact of mats in these environments and the microbial communities associated with them. Our data demonstrate that these mats attain surprisingly high rates of carbon (CO2) and dinitrogen (N2) fixation when liquid water is available, in some cases comparable to rates in warmer temperate or tropical environments. C and N2 fixation in Dry Valley mats in turn substantially elevate dissolved organic C and inorganic N pools and thereby promote enhanced microbial secondary production. Moreover, the microbial community fingerprint of these mats is unique compared with the more ubiquitous dry soils that do not contain mats. Components of the heterotrophic microbiota may also contribute substantially to N inputs through N2 fixation.