Sanath Kondaveeti, Dae-Hyeon Choi, Md Tabish Noori et al.

Energies • 0

<jats:p>Ammonia removal from wastewater was successfully achieved by simultaneous nitrification and denitrification (SND) in a double-chamber microbial electrolysis cell (MEC). The MEC operations at different applied voltages (0.7 to 1.5 V) and initial ammonia concentrations (30 to 150 mg/L) were conducted in order to evaluate their effects on MEC performance in batch mode. The maximum nitrification efficiency of 96.8% was obtained in the anode at 1.5 V, followed by 94.11% at 1.0 V and 87.05% at 0.7. At 1.5 V, the initial ammonia concentration considerably affected the nitrification rate, and the highest nitrification rate constant of 0.1601/h was determined from a first-order linear regression at 30 mg/L ammonium nitrogen. The overall total nitrogen removal efficiency was noted to be 85% via the SND in the MEC operated at an initial ammonium concentration of 50 mg/L and an applied cell voltage of 1.5 V. The MEC operation in continuous mode could remove ammonia (50 mg/L) in a series of anode and cathode chambers at the nitrogen removal rate of 170 g-N/m3.d at an HRT of 15. This study suggests that a standalone dual-chamber MEC can efficiently remove ammonia via the SND process without needing additional organic substrate and aeration, which makes this system viable for field applications.</jats:p>

Qianli Yu, Wei Xiong, Donggen Huang et al.

Environmental Engineering Research • 0

<jats:p>Microbial electrolysis cell (MEC) has been constructed to study the degradation characters of 2-chloro-4-nitrophenol (2C4NP) in waste water. The effects of applied voltage, initial concentration of substrate and co-matrix species on the reduction and degradation of 2C4NP were studied. Qualitative and quantitative analysis of 2C4NP residues and degradation intermediate by using UV-Vis, HPLC, HPLC/MS/MS, IC and other analytical testing techniques. The degradation mechanism of 2C4NP in MEC cathode was proposed. The results showed that electron and electroactive microorganisms would produce coupling effect and accelerate the degradation of 2C4NP under adding 0.5 V DC; Under the condition of satisfying the C/N ratio of electroactive anaerobic microorganism, the addition of organic substances such as glucose and sodium acetate which were easily degraded by microorganisms would hinder the degradation of 2C4NP in the cathode compartment. 2C4NP can be effectively degraded by adding appropriate amount of glucose as carbon source with the low C/N. 2C4NP undergoes reduction, dechlorination, denitrification and assimilation in the cathode compartment to form 2-chloro-4-aminophenol, 4-aminophenol, 2-chlorophenol, 2-chloro-4-hydroxyphenol, nitrophenol, hydroquinone, 4-hydroxyhexadienoic acid semialdehyde, valeric acid, oxalic acid and many other intermediate products. According to the degradation intermediates, the degradation mechanism of 2C4NP in the cathode compartment was presumed.</jats:p>

Qiongfang Zhang, Mei‐Yin Wu, Nuerla Ailijiang et al.

International Journal of Environmental Research and Public Health • 2022

Diclofenac, ibuprofen, and carbamazepine are frequently detected in the environment, where they pose a threat to organisms and ecosystems. We developed anaerobic–aerobic coupled upflow bioelectrochemical reactors (AO-UBERs) with different voltages, hydraulic retention times (HRTs), and types of electrode conversion, and evaluated the ability of the AO-UBERs to remove the three pharmaceuticals. This study showed that when a voltage of 0.6 V was applied, the removal rate of ibuprofen was slightly higher in the system with aerobic cathodic and anaerobic anodic chambers (60.2 ± 11.0%) with HRT of 48 h than in the control systems, and the removal efficiency reached stability faster. Diclofenac removal was 100% in the 1.2 V system with aerobic anodic and anaerobic cathodic chambers, which was greater than in the control system (65.5 ± 2.0%). The contribution of the aerobic cathodic–anodic chambers to the removal of ibuprofen and diclofenac was higher than that of the anaerobic cathodic–anodic chambers. Electrical stimulation barely facilitated the attenuation of carbamazepine. Furthermore, biodegradation-related species (Methyloversatilis, SM1A02, Sporomusa, and Terrimicrobium) were enriched in the AO-UBERs, enhancing pharmaceutical removal. The current study sheds fresh light on the interactions of bacterial populations with the removal of pharmaceuticals in a coupled system.

M. Zeppilli, Edoardo Dell’Armi, M. L. Di Franca et al.

SSRN Electronic Journal • 2022

In the present study, the sequential reductive/oxidative bioelectrochemical process has been tested with real groundwater from a contaminated site in Northern Italy for chlorinated aliphatic hydrocarbons (CAHs) removal. The sequential system was developed by connecting in series two membrane-less microbial electrolysis cells (MECs) equipped with an internal graphite counter electrode. The first MEC aimed at the CAHs reductive dechlorination (RD) and was constituted of a granular graphite working electrode. In the second MEC, a mixed metal oxide working electrode stimulated the oxidative dechlorination of the low chlorinated RD's by-products through oxygen production. The sequential process allowed complete mineralization of the CAHs contained in the real groundwater. A complete reduction of the perchloroethylene into vinyl chloride (VC) was observed in the first MEC polarized at (cid:0) 450 mV vs SHE, while the resulting VC was oxidized with a 92 ± 2 % efficiency in the second MEC due to the HRT increment from 0.7 to 1.7 days. Biomarkers of the reductive ( Dehalococcoides mccartyi 16S rRNA and reductive dehalogenase genes) and oxidative ( etnE , etnC genes) dechlorination have been monitored in the two MECs along with the ecotoxicity tests. Overall, they provide information on the efficiency of the applied technology and allow to assess the potential adverse effects. According to the Tetrahymena pyr-iformis reproduction inhibition test and Panagrellus redivivus mortality tests, showed a significant ecotoxicity reduction with respect its initial inhibitory effect at the tested concentrations.

R. A. Nastro, Anna Salvian, Chandrasekhar Kuppam et al.

Microorganisms • 2023

The need for greener processes to satisfy the demand of platform chemicals together with the possibility of reusing CO2 from human activities has recently encouraged research on the set-up, optimization, and development of bioelectrochemical systems (BESs) for the electrosynthesis of organic compounds from inorganic carbon (CO2, HCO3−). In the present study, we tested the ability of Clostridium saccharoperbutylacetonicum N1-4 (DSMZ 14923) to produce acetate and D-3-hydroxybutyrate from inorganic carbon present in a CO2:N2 gas mix. At the same time, we tested the ability of a Shewanella oneidensis MR1 and Pseudomonas aeruginosa PA1430/CO1 consortium to provide reducing power to sustain carbon assimilation at the cathode. We tested the performance of three different systems with the same layouts, inocula, and media, but with the application of 1.5 V external voltage, of a 1000 Ω external load, and without any connection between the electrodes or external devices (open circuit voltage, OCV). We compared both CO2 assimilation rate and production of metabolites (formate, acetate 3-D-hydroxybutyrate) in our BESs with the values obtained in non-electrogenic control cultures and estimated the energy used by our BESs to assimilate 1 mol of CO2. Our results showed that C. saccharoperbutylacetonicum NT-1 achieved the maximum CO2 assimilation (95.5%) when the microbial fuel cells (MFCs) were connected to the 1000 Ω external resistor, with the Shewanella/Pseudomonas consortium as the only source of electrons. Furthermore, we detected a shift in the metabolism of C. saccharoperbutylacetonicum NT-1 because of its prolonged activity in BESs. Our results open new perspectives for the utilization of BESs in carbon capture and electrosynthesis of platform chemicals.

Balamurugan Thangavel, G. Venkatachalam, Joong Ho Shin

ACS Applied Bio Materials • 2024

Bilirubin oxidases (BODs) [EC 1.3.3.5 - bilirubin: oxygen oxido-reductase] are enzymes that belong to the multicopper oxidase family and can oxidize bilirubin, diphenols, and aryl amines and reduce the oxygen by direct four-electron transfer from the electrode with almost no electrochemical overpotential. Therefore, BOD is a promising bioelectrocatalyst for (self-powered) biosensors and/or enzymatic fuel cells. The advantages of electrochemically active BOD enzymes include selective biosensing, biocatalysis for efficient energy conversion, and electrosynthesis. Owing to the rise in publications and patents, as well as the expanding interest in BODs for a range of physiological conditions, this Review analyzes scientific literature reports on BOD enzymes and current hypotheses on their bioelectrocatalysis. This Review evaluates the specific research outcomes of the BOD in enzyme (protein) engineering, immobilization strategies, and challenges along with their bioelectrochemical properties, limitations, and applications in the fields of (i) biosensors, (ii) self-powered biosensors, and (iii) biofuel cells for powering bioelectronics.

Yueyue Zhou, Lu Lin, Heng Wang et al.

Communications Biology • 2020

Ferulic acid is a ubiquitous phenolic compound in lignocellulose, which is recognized for its role in the microbial carbon catabolism and industrial value. However, its recalcitrance and toxicity poses a challenge for ferulic acid-to-bioproducts bioconversion. Here, we develop a genome editing strategy for Pseudomonas putida KT2440 using an integrated CRISPR/Cas9n-λ-Red system with pyrF as a selection marker, which maintains cell viability and genetic stability, increases mutation efficiency, and simplifies genetic manipulation. Via this method, four functional modules, comprised of nine genes involved in ferulic acid catabolism and polyhydroxyalkanoate biosynthesis, were integrated into the genome, generating the KTc9n20 strain. After metabolic engineering and optimization of C/N ratio, polyhydroxyalkanoate production was increased to ~270 mg/L, coupled with ~20 mM ferulic acid consumption. This study not only establishes a simple and efficient genome editing strategy, but also offers an encouraging example of how to apply this method to improve microbial aromatic compound bioconversion. Yueyue Zhou et al. develop a genetic engineering method that increases the production of polyhydroxyalkanoate from ferulic acid, which is toxic at high concentrations. This study provides insight into the bioconversion of the aromatic compound in Pseudomonas.

S.J.B. Mallinson, Melodie M. Machovina, Rodrigo L. Silveira et al.

Nature Communications • 2018

Microbial aromatic catabolism offers a promising approach to convert lignin, a vast source of renewable carbon, into useful products. Aryl-O-demethylation is an essential biochemical reaction to ultimately catabolize coniferyl and sinapyl lignin-derived aromatic compounds, and is often a key bottleneck for both native and engineered bioconversion pathways. Here, we report the comprehensive characterization of a promiscuous P450 aryl-O-demethylase, consisting of a cytochrome P450 protein from the family CYP255A (GcoA) and a three-domain reductase (GcoB) that together represent a new two-component P450 class. Though originally described as converting guaiacol to catechol, we show that this system efficiently demethylates both guaiacol and an unexpectedly wide variety of lignin-relevant monomers. Structural, biochemical, and computational studies of this novel two-component system elucidate the mechanism of its broad substrate specificity, presenting it as a new tool for a critical step in biological lignin conversion. Catabolizing lignin-derived aromatic compounds requires an aryl-O-demethylation step. Here the authors present the structures of GcoA and GcoB, a cytochrome P450-reductase pair that catalyzes aryl-O-demethylations and show that GcoA displays broad substrate specificity, which is of interest for biotechnology applications.

Yan Lu, Shouyu Zhang, Shibo Sun et al.

Insects • 2021

Simple Summary Black soldier fly larvae (BSFL) have received global research interest and industrial application due to their high performance on the organic waste treatment. However, the substrate C/N property, which may affect larvae development and the waste bioconversion process greatly, is significantly less studied. The current study focused on the food waste treatment by BSFL, compared the nitrogen supplying effects of 9 nitrogen species (i.e., NH4Cl, NaNO3, urea, uric acid, Gly, L-Glu, L-Glu:L-Asp (1:1, w/w), soybean flour, and fish meal), and further examined the C/N effects on the larval development and bioconversion process. We found that NH4Cl and NaNO3 led to poor larval growth and survival, while 7 organic nitrogen species exerted no harm to the larvae. Urea was further chosen to adjust the C/Ns. Results showed that lowering the C/N from the initial 21:1 to 18:1–14:1 improved the waste reduction and larvae production performance, and C/N of 18:1–16:1 was further beneficial for the larval protein and lipid bioconversion, whereas C/N of 12:1–10:1 resulted in a significant performance decline. Therefore, the C/N range of 18:1–16:1 is likely the optimal condition for food waste treatment by BSFL and adjusting food waste C/N with urea could be a practical method for the performance improvement. Abstract Biowaste treatment by black soldier fly larvae (BSFL, Hermetia illucens) has received global research interest and growing industrial application. Larvae farming conditions, such as temperature, pH, and moisture, have been critically examined. However, the substrate carbon to nitrogen ratio (C/N), one of the key parameters that may affect larval survival and bioconversion efficiency, is significantly less studied. The current study aimed to compare the nitrogen supplying effects of 9 nitrogen species (i.e., NH4Cl, NaNO3, urea, uric acid, Gly, L-Glu, L-Glu:L-Asp (1:1, w/w), soybean flour, and fish meal) during food waste larval treatment, and further examine the C/N effects on the larval development and bioconversion process, using the C/N adjustment with urea from the initial 21:1 to 18:1, 16:1, 14:1, 12:1, and 10:1, respectively. The food wastes were supplied with the same amount of nitrogen element (1 g N/100 g dry wt) in the nitrogen source trial and different amount of urea in the C/N adjustment trial following larvae treatment. The results showed that NH4Cl and NaNO3 caused significant harmful impacts on the larval survival and bioconversion process, while the 7 organic nitrogen species resulted in no significant negative effect. Further adjustment of C/N with urea showed that the C/N range between 18:1 and 14:1 was optimal for a high waste reduction performance (73.5–84.8%, p < 0.001) and a high larvae yield (25.3–26.6%, p = 0.015), while the C/N range of 18:1 to 16:1 was further optimal for an efficient larval protein yield (10.1–11.1%, p = 0.003) and lipid yield (7.6–8.1%, p = 0.002). The adjustment of C/N influenced the activity of antioxidant enzymes, such as superoxide dismutase (SOD, p = 0.015), whereas exerted no obvious impact on the larval amino acid composition. Altogether, organic nitrogen is more suitable than NH4Cl and NaNO3 as the nitrogen amendment during larval food waste treatment, addition of small amounts of urea, targeting C/N of 18:1–14:1, would improve the waste reduction performance, and application of C/N at 18:1–16:1 would facilitate the larval protein and lipid bioconversion process.

X. Qi, Wenlong Yan, Zhibei Cao et al.

Microorganisms • 2021

Polyethylene terephthalate (PET) is a widely used plastic that is polymerized by terephthalic acid (TPA) and ethylene glycol (EG). In recent years, PET biodegradation and bioconversion have become important in solving environmental plastic pollution. More and more PET hydrolases have been discovered and modified, which mainly act on and degrade the ester bond of PET. The monomers, TPA and EG, can be further utilized by microorganisms, entering the tricarboxylic acid cycle (TCA cycle) or being converted into high value chemicals, and finally realizing the biodegradation and bioconversion of PET. Based on synthetic biology and metabolic engineering strategies, this review summarizes the current advances in the modified PET hydrolases, engineered microbial chassis in degrading PET, bioconversion pathways of PET monomers, and artificial microbial consortia in PET biodegradation and bioconversion. Artificial microbial consortium provides novel ideas for the biodegradation and bioconversion of PET or other complex polymers. It is helpful to realize the one-step bioconversion of PET into high value chemicals.

L. Jönsson, B. Alriksson, N. Nilvebrant

Biotechnology for Biofuels • 2013

Bioconversion of lignocellulose by microbial fermentation is typically preceded by an acidic thermochemical pretreatment step designed to facilitate enzymatic hydrolysis of cellulose. Substances formed during the pretreatment of the lignocellulosic feedstock inhibit enzymatic hydrolysis as well as microbial fermentation steps. This review focuses on inhibitors from lignocellulosic feedstocks and how conditioning of slurries and hydrolysates can be used to alleviate inhibition problems. Novel developments in the area include chemical in-situ detoxification by using reducing agents, and methods that improve the performance of both enzymatic and microbial biocatalysts.

Baige Zhang, Hongzhao Li, Limei Chen et al.

Processes • 2022

Waste straw biomass is an abundant renewable bioresource raw material on Earth. Its stubborn wooden cellulose structure limits straw lignocellulose bioconversion into value-added products (e.g., biofuel, chemicals, and agricultural products). Compared to physicochemical and other preprocessing techniques, the steam explosion method, as a kind of hydrothermal method, was considered as a practical, eco-friendly, and cost-effective method to overcome the above-mentioned barriers during straw lignocellulose bioconversion. Steam explosion pretreatment of straw lignocellulose can effectively improve the conversion efficiency of producing biofuels and value-added chemicals and is expected to replace fossil fuels and partially replace traditional chemical fertilizers. Although the principles of steam explosion destruction of lignocellulosic structures for bioconversion to liquid fuels and producing solid biofuel were well known, applications of steam explosion in productions of value-added chemicals, organic fertilizers, biogas, etc. were less identified. Therefore, this review provides insights into advanced methods of utilizing steam explosion for straw biomass conversion as well as their corresponding processes and mechanisms. Finally, the current limitations and prospects of straw biomass conversion with steam explosion technology were elucidated.

V. Venugopal

Frontiers in Sustainable Food Systems • 2021

The seafood industry generates large volumes of waste. These include processing discards consisting of shell, head, bones intestine, fin, skin, voluminous amounts of wastewater discharged as effluents, and low-value under-utilized fish, which are caught as by-catch of commercial fishing operations. The discards, effluents, and by-catch are rich in nutrients including proteins, amino acids, lipids containing good proportions of polyunsaturated fatty acids (PUFA), carotenoids, and minerals. The seafood waste is, therefore, responsible for loss of nutrients and serious environmental hazards. It is important that the waste is subjected to secondary processing and valorization to address the problems. Although chemical processes are available for waste treatment, most of these processes have inherent weaknesses. Biological treatments, however, are environmentally friendly, safe, and cost-effective. Biological treatments are based on bioconversion processes, which help with the recovery of valuable ingredients from by-catch, processing discards, and effluents, without losing their inherent bioactivities. Major bioconversion processes make use of microbial fermentations or actions of exogenously added enzymes on the waste components. Recent developments in algal biotechnology offer novel processes for biotransformation of nutrients as single cell proteins, which can be used as feedstock for the recovery of valuable ingredients and also biofuel. Bioconversion options in conjunction with a bio-refinery approach have potential for eco-friendly and economical management of seafood waste that can support sustainable seafood production.

Jennifer Michellin Kiruba N, A. Saeid

International Journal of Molecular Sciences • 2022

The plant-microbe holobiont has garnered considerable attention in recent years, highlighting its importance as an ecological unit. Similarly, manipulation of the microbial entities involved in the rhizospheric microbiome for sustainable agriculture has also been in the limelight, generating several commercial bioformulations to enhance crop yield and pest resistance. These bioformulations were termed biofertilizers, with the consistent existence and evolution of different types. However, an emerging area of interest has recently focused on the application of these microorganisms for waste valorization and the production of “bio-organic” fertilizers as a result. In this study, we performed a bibliometric analysis and systematic review of the literature retrieved from Scopus and Web of Science to determine the type of microbial inoculants used for the bioconversion of waste into “bio-organic” fertilizers. The Bacillus, Acidothiobacillus species, cyanobacterial biomass species, Aspergillus sp. and Trichoderma sp. were identified to be consistently used for the recovery of nutrients and bioconversion of wastes used for the promotion of plant growth. Cyanobacterial strains were used predominantly for wastewater treatment, while Bacillus, Acidothiobacillus, and Aspergillus were used on a wide variety of wastes such as sawdust, agricultural waste, poultry bone meal, crustacean shell waste, food waste, and wastewater treatment plant (WWTP) sewage sludge ash. Several bioconversion strategies were observed such as submerged fermentation, solid-state fermentation, aerobic composting, granulation with microbiological activation, and biodegradation. Diverse groups of microorganisms (bacteria and fungi) with different enzymatic functionalities such as chitinolysis, lignocellulolytic, and proteolysis, in addition to their plant growth promoting properties being explored as a consortium for application as an inoculum waste bioconversion to fertilizers. Combining the efficiency of such functional and compatible microbial species for efficient bioconversion as well as higher plant growth and crop yield is an enticing opportunity for “bio-organic” fertilizer research.

Lu Lin

Biotechnology for Biofuels and Bioproducts • 2022

Lignocellulose is the most abundant organic carbon polymer on the earth. Its decomposition and conversion greatly impact the global carbon cycle. Furthermore, it provides feedstock for sustainable fuel and other value-added products. However, it continues to be underutilized, due to its highly recalcitrant and heterogeneric structure. Microorganisms, which have evolved versatile pathways to convert lignocellulose, undoubtedly are at the heart of lignocellulose conversion. Numerous studies that have reported successful metabolic engineering of individual strains to improve biological lignin valorization. Meanwhile, the bottleneck of single strain modification is becoming increasingly urgent in the conversion of complex substrates. Alternatively, increased attention has been paid to microbial consortia, as they show advantages over pure cultures, e.g., high efficiency and robustness. Here, we first review recent developments in microbial communities for lignocellulose bioconversion. Furthermore, the emerging area of synthetic ecology, which is an integration of synthetic biology, ecology, and computational biology, provides an opportunity for the bottom-up construction of microbial consortia. Then, we review different modes of microbial interaction and their molecular mechanisms, and discuss considerations of how to employ these interactions to construct synthetic consortia via synthetic ecology, as well as highlight emerging trends in engineering microbial communities for lignocellulose bioconversion.

D. Peguero, M. Gold, D. Vandeweyer et al.

Frontiers in Sustainable Food Systems • 2022

As the world population increases, food demand and agricultural activity will also increase. However, ~30–40% of the food produced today is lost or wasted along the production chain. Increasing food demands would only intensify the existing challenges associated with agri-food waste management. An innovative approach to recover the resources lost along the production chain and convert them into value-added product(s) would be beneficial. An alternative solution is the use of the larvae of the black soldier fly (BSFL), Hermetia illucens L., which can grow and convert a wide range of organic waste materials into insect biomass with use as animal feed, fertilizer and/or bioenergy. However, the main concern when creating an economically viable business is the variability in BSFL bioconversion and processing due to the variability of the substrate. Many factors, such as the nutritional composition of the substrate heavily impact BSFL development. Another concern is that substrates with high lignin and cellulose contents have demonstrated poor digestibility by BSFL. Studies suggest that pretreatment methods may improve the digestibility and biodegradability of the substrate by BSFL. However, a systematic review of existing pretreatment methods that could be used for enhancing the bioconversion of these wastes by BSFL is lacking. This paper provides a state-of-the-art review on the potential pretreatment methods that may improve the digestibility of substrates by BSFL and consequently the production of BSFL. These processes include but are not limited to, physical (e.g., mechanical and thermal), chemical (alkaline treatments), and biological (bacterial and fungal) treatments.

Surbhi Sharma, M. Tsai, Vishal Sharma et al.

Environments • 2022

An upsurge in global population and rapid urbanization has accelerated huge dependence on petroleum-derived fuels and consequent environmental concerns owing to greenhouse gas emissions in the atmosphere. An integrated biorefinery uses lignocellulosic feedstock as raw material for the production of renewable biofuels, and other fine chemicals. The sustainable bio-economy and the biorefinery industry would benefit greatly from the effective use of lignocellulosic biomass obtained from agricultural feedstocks to replace petrochemical products. Lignin, cellulose, hemicellulose, and other extractives, which are essential components of lignocellulosic biomass, must be separated or upgraded into useful forms in order to fully realize the potential of biorefinery. The development of low-cost and green pretreatment technologies with effective biomass deconstruction potential is imperative for an efficient bioprocess. The abundance of microorganisms along with their continuous production of various degradative enzymes makes them suited for the environmentally friendly bioconversion of agro-industrial wastes into viable bioproducts. The present review highlights the concept of biorefinery, lignocellulosic biomass, and its valorization by green pretreatment strategies into biofuels and other biochemicals. The major barriers and challenges in bioconversion technologies, environmental sustainability of the bioproducts, and promising solutions to alleviate those bottlenecks are also summarized.

Thi Ngoc Anh Tran, Jin‐Sung Son, M. Awais et al.

Bioengineering • 2023

Ginsenosides are a group of bioactive compounds isolated from Panax ginseng. Conventional major ginsenosides have a long history of use in traditional medicine for both illness prevention and therapy. Bioconversion processes have the potential to create new and valuable products in pharmaceutical and biological activities, making them both critical for research and highly economic to implement. This has led to an increase in the number of studies that use major ginsenosides as a precursor to generate minor ones using β-glucosidase. Minor ginsenosides may also have useful properties but are difficult to isolate from raw ginseng because of their scarcity. Bioconversion processes have the potential to create novel minor ginsenosides from the more abundant major ginsenoside precursors in a cost-effective manner. While numerous bioconversion techniques have been developed, an increasing number of studies have reported that β-glucosidase can effectively and specifically generate minor ginsenosides. This paper summarizes the probable bioconversion mechanisms of two protopanaxadiol (PPD) and protopanaxatriol (PPT) types. Other high-efficiency and high-value bioconversion processes using complete proteins isolated from bacterial biomass or recombinant enzymes are also discussed in this article. This paper also discusses the various conversion and analysis methods and their potential applications. Overall, this paper offers theoretical and technical foundations for future studies that will be both scientifically and economically significant.

S. Siddiqui, Özge Süfer, Gülşah Çalışkan Koç et al.

Environment, Development and Sustainability • 2024

Food security remains a pressing concern in the face of an increasing world population and environmental challenges. As climate change, biodiversity loss, and water scarcity continue to impact agricultural productivity, traditional livestock farming faces limitations in meeting the growing global demand for meat and dairy products. In this context, black soldier fly larvae (BSFL) have emerged as a promising alternative for sustainable food production. BSFL possess several advantages over conventional livestock, including their rapid growth, adaptability to various organic waste substrates, and low environmental impact. Their bioconversion rate, the ability to transform organic waste into valuable products, and final product optimization are key factors that enhance their potential as a nutrient-rich protein source, fertilizer, and biofuel. This review explores strategies to enhance the bioconversion rate and improve the end products derived from BSF treatment. It highlights the benefits of using BSFL over other interventions and underscores the significance of optimizing their bioconversion rate to meet the challenges of global food security sustainably. Despite the promising prospects of BSF-derived products, consumer acceptance and regulatory hurdles remain critical aspects to address in realizing their full market potential. The utilization of BSFL as a sustainable source of food and feed can contribute to waste management, reduce environmental pollution, and address the pressing issue of food security in an environmentally responsible manner. However, there is a need for further research and innovation to ensure the safety, quality, and economic viability of BSF-based products for both animal and human consumption.

Pedro Fernandes, Joaquim M.S. Cabral

Encyclopedia of Industrial Biotechnology • 0

<jats:title>Abstract</jats:title><jats:p>Steroids constitute a particular class of lipids characterized by a typical tetracyclic skeleton, composed of one five‐member ring and three fused six‐member rings. Steroids are widely used as therapeutic agents and since their inception in the market, research efforts have been made in order to improve production processes as well as to develop novel synthetic molecules, with enhanced efficiency and reduced side effects. Given the complexity of the steroid skeleton, total chemical synthesis of given steroid molecules is hardly an effective approach; hence, steroid production processes rely on chemical modifications of educts that structurally resemble the targeted product. Still, steroid molecules present multiple chiral centers, a feature that makes particularly appealing the use of the selective microbial catalysts to provide a pathway that does not require protection, and additional deprotection steps. Furthermore, bioconversions are performed in a milder, greener environment, as compared to the purely chemical approach. The present work aims to provide an overview of steroid bioconversions. The potential of biologic agents (microbial cells/enzymes) to catalyze the conversion of a wide array of steroid educts will be presented, with particular emphasis on those that have achieved particular relevance, as well as on key aspects within the field. The chapter ends with the perspective trends in the field of steroid bioconversions</jats:p>

Eleni Theodosiou

Catalysts • 0

<jats:p>Yarrowia lipolytica has been a valuable biotechnological workhorse for the production of commercially important biochemicals for over 70 years. The knowledge gained so far on the native biosynthetic pathways, as well as the availability of numerous systems and synthetic biology tools, enabled not only the regulation and the redesign of the existing metabolic pathways, but also the introduction of novel synthetic ones; further consolidating the position of the yeast in industrial biotechnology. However, for the development of competitive and sustainable biotechnological production processes, bioengineering should be reinforced by bioprocess optimization strategies. Although there are many published reviews on the bioconversion of various carbon sources to value-added products by Yarrowia lipolytica, fewer works have focused on reviewing up-to-date strain, medium, and process engineering strategies with an aim to emphasize the significance of integrated engineering approaches. The ultimate goal of this work is to summarize the necessary knowledge and inspire novel routes to manipulate at a systems level the yeast biosynthetic machineries by combining strain and bioprocess engineering. Due to the increasing surplus of biodiesel-derived waste glycerol and the favored glycerol-utilization metabolic pathways of Y. lipolytica over other carbon sources, the present review focuses on pure and crude glycerol-based biomanufacturing.</jats:p>

, Bachir Bourroubey, Nadia Chelli et al.

French-Ukrainian Journal of Chemistry • 2023

<jats:p>In the context of biological studies on an antidiabetic plant, we conducted an ethnobotanical study of Pistacia lentiscus L., collected from two regions in the Northwest of Algeria: Mesra (Mostaganem city) and Mohammadia (Mascara city), followed by a chemical and antioxidant studies of methanolic extracts the leaves of this plant. Ethnobotanically, the plant has a large use, especially in traditional medicine as antidiabetic, anti-inflammatory, antibacterial and cosmetics, such as polishing teeth and maintaining gums, moisturizing hair and protecting follicles, polishing skin and perfuming. Also, results showed its richness in active metabolites, such as polyphenols, flavonoids and tanins. The Mesra methanolic extract was more effective than Mohammadia’s one with 90.12 ± 2.74 mg EqGAc/g DW, 41.86 ± 1.52 mg EqCer/g DW, 27.45 ± 056 mg EqCat/g DW while Mohammadia extract revealed 80.31 ± 1.42 mg EqGAc/g DW, 33.92 ± 1.71 mg Eq Cer/g DW, 27.61 ±1.53 mg EqCat/g DW for phenolic compounds, flavonoids and tannins respectively. In addition, the antioxidant study revealed a powerful antioxidant effect with an IC50 of 0.06 mg/mL and 0.1 mg/mL for methanolic extract. This antidiabetic plant is valuable from a health point of view, so we are seeking to confirm another biological activity in vitro and in vivo.</jats:p>

Juana Pérez, Aurelio Moraleda-Muñoz

Mycofactories • 2011

<jats:p>Lignocellulosic materials as industrial, agricultural, and forest residues account for the majority of the total renewable biomass present on Earth. Some fungi are equipped with potent enzymatic systems involved in the hydrolysis or oxidation of these biopolymers. Herein, we provide an update of lignocellulose biodegradation processes and the main biotechnological applications of lignocellulolytic fungi or their enzymes in biotransformation and biodegradation of wastes, and in the conversion of biomass into valuable products.</jats:p>

Shaoan Cheng, D. Xing, D. Call et al.

Environmental Science &amp; Technology • 2009

New sustainable methods are needed to produce renewable energy carriers that can be stored and used for transportation, heating, or chemical production. Here we demonstrate that methane can directly be produced using a biocathode containing methanogens in electrochemical systems (abiotic anode) or microbial electrolysis cells (MECs; biotic anode) by a process called electromethanogenesis. At a set potential of less than -0.7 V (vs Ag/AgCl), carbon dioxide was reduced to methane using a two-chamber electrochemical reactor containing an abiotic anode, a biocathode, and no precious metal catalysts. At -1.0 V, the current capture efficiency was 96%. Electrochemical measurements made using linear sweep voltammetry showed that the biocathode substantially increased current densities compared to a plain carbon cathode where only small amounts of hydrogen gas could be produced. Both increased current densities and very small hydrogen production rates by a plain cathode therefore support a mechanism of methane production directly from current and not from hydrogen gas. The biocathode was dominated by a single Archaeon, Methanobacterium palustre. When a current was generated by an exoelectrogenic biofilm on the anode growing on acetate in a single-chamber MEC, methane was produced at an overall energy efficiency of 80% (electrical energy and substrate heat of combustion). These results show that electromethanogenesis can be used to convert electrical current produced from renewable energy sources (such as wind, solar, or biomass) into a biofuel (methane) as well as serving as a method for the capture of carbon dioxide.

C. Wyman, B. Dale, Venkatesh Balan et al.

Aqueous Pretreatment of Plant Biomass for Biological and Chemical Conversion to Fuels and Chemicals • 2013

Cellulosic biomass is the only resource from which liquid fuels so vital to transportation can be made at alarge scale sustainably and also minimize the conflict with food production [1]. Furthermore, cellulosic bio-mass costing about $60/dry ton is competitive with petroleum at about $20/barrel on an equivalent energycontent basis [2]. Therefore, the primary challenge to competitiveness is low-cost processing of cellulosicbiomass to fuels, and biological routes can take advantage of the rapidly evolving tools of biotechnology toradically reduce costs [1,3]. The economic challenge for biological options is to overcome the natural resist-ance of plants to release of sugars that are the building blocks of cellulose and hemicellulose and typicallycomprise two-thirds to three-quarters of cellulosic materials. Although modification of plants to facilitatesugar release and better enzyme/organism combinations that can attack cellulosic materials more effectivelyare often favored to improve performance [1], to date, biomass pretreatment has been essential to achievingthe high yields of sugars vital to economic success and is likely to remain an essential step in the overallconversion system [4]. At this point, we are faced with the conundrum that pretreatment is among the mostexpensive single steps in biological processing [5], but unit production costs are even higher if pretreatment iseliminated, due to the resulting low product yields [6]. It has therefore been stated that the “only step moreexpensive than pretreatment is no pretreatment” [4]. Full attention must be focused on developing lower-costpretreatment technologies that can integrate with advanced biological conversion systems and perhaps takeadvantage of plants that have been modified to facilitate sugar release.The Biomass Refining Consortium for Applied Fundamentals and Innovation (CAFI) was originally con-ceived in late 1999 in a meeting in Dallas, Texas among pretreatment leaders interested in working collabo-ratively. It was formally organized in early 2000 in a Chicago meeting among this team [7]. During theentire CAFI lifetime, the following goals were set: Develop data on leading pretreatments using common feedstocks, enzymes, analytical methods, materialand energy balance methods and costing methods. Seek to understand mechanisms that influence performance and differentiate pretreatments by providinga technology base to facilitate commercial use and identifying promising paths to advance pretreatmenttechnologies that achieve lower costs. Train and educate students in biomass conversion technologies.A key objective was to provide information to help industry select technologies fo r commercial applica-tions and not to “downselect” pretreatments. Rather, it was vital to provide extensive data on promisingoptions so that others could decide which technologies t o employ and avoid a lack of data clouding decisions.The CAFI team was fortunate to be selected for funding by a new United States Department of Agricul-ture (USDA) Program called the Initiative for Future Agricultural and Food Systems (IFAFS) through acompetitive solicitation released in the spring of 2000. Although the program unfortunately had a short life,the IFAFS approach was unique in that it funded large collaborative projects focused on advancing andapplying biomass conversion technologies, consistent with the CAFI spirit. In this inaugural CAFI projectthat ran from 2000 to 2004, now designated CAFI 1, the emphasis was on comparative data from applica-tion of leading pretreatments to a shared source of corn stover, with most of the work focused on perform-ance from just the pretreatment and enzymatic hydrolysis steps [7]. In 2004, the Office of the BiomassProgram (OBP) of the US Department of Energy selected the CAFI team for a second project as a result ofa competitive solicitation. This project, now known to our team as CAFI 2, applied most of the pretreatmenttechnologies employed in CAFI 1 to poplar wood but with more data developed on enzymatic hydrolysisand fermentation [8]. Following completion of the CAFI 2 work, OBP funded the team to apply the samestable of pretreatment technologies to switchgrass. This latter CAFI 3 project was somewhat broader inscope than prior projects in that, in addition to determining yields from pretreatment and enzymatic

Han Li, J. Liao

Energy &amp; Environmental Science • 2013

To achieve sustainable growth of human society, fossil fuels must eventually be replaced with renewable resources. Ultimately, the energy and carbon in fuels and chemicals synthesized must come from the sun and CO2 directly. Biological systems hold the promise to catalyze the synthesis of such fuels or chemicals. This article discusses recent advances in developing biofuel production processes from CO2, which include photosynthetic processes using algae and cyanobacteria and the non-photosynthetic “electrofuel” processes using Ralstonia eutropha and other lithoautotrophic microorganisms. Each of these processes involves strengths and weaknesses. While none of these processes have achieved industrial success, the challenges involved may point the direction for further improvement within the limit of theoretical possibility. Finally, all biological processes produce cell mass rich in protein. Regenerating ammonium by deamination of hydrolyzed proteins may close the loop of the global nitrogen cycle, which is also one of the major challenges in large scale biological processes.

Ville R. I. Kaila

Accounts of Chemical Research • 2021

Conspectus Biological energy conversion is catalyzed by membrane-bound proteins that transduce chemical or light energy into energy forms that power endergonic processes in the cell. At a molecular level, these catalytic processes involve elementary electron-, proton-, charge-, and energy-transfer reactions that take place in the intricate molecular machineries of cell respiration and photosynthesis. Recent developments in structural biology, particularly cryo-electron microscopy (cryoEM), have resolved the molecular architecture of several energy transducing proteins, but detailed mechanistic principles of their charge transfer reactions still remain poorly understood and a major challenge for modern biochemical research. To this end, multiscale molecular simulations provide a powerful approach to probe mechanistic principles on a broad range of time scales (femtoseconds to milliseconds) and spatial resolutions (101–106 atoms), although technical challenges also require balancing between the computational accuracy, cost, and approximations introduced within the model. Here we discuss how the combination of atomistic (aMD) and hybrid quantum/classical molecular dynamics (QM/MM MD) simulations with free energy (FE) sampling methods can be used to probe mechanistic principles of enzymes responsible for biological energy conversion. We present mechanistic explorations of long-range proton-coupled electron transfer (PCET) dynamics in the highly intricate respiratory chain enzyme Complex I, which functions as a redox-driven proton pump in bacterial and mitochondrial respiratory chains by catalyzing a 300 Å fully reversible PCET process. This process is initiated by a hydride (H–) transfer between NADH and FMN, followed by long-range (>100 Å) electron transfer along a wire of 8 FeS centers leading to a quinone biding site. The reduction of the quinone to quinol initiates dissociation of the latter to a second membrane-bound binding site, and triggers proton pumping across the membrane domain of complex I, in subunits up to 200 Å away from the active site. Our simulations across different size and time scales suggest that transient charge transfer reactions lead to changes in the internal hydration state of key regions, local electric fields, and the conformation of conserved ion pairs, which in turn modulate the dynamics of functional steps along the reaction cycle. Similar functional principles, which operate on much shorter length scales, are also found in some unrelated proteins, suggesting that enzymes may employ conserved principles in the catalysis of biological energy transduction processes.

Ryan Davis, Ling Tao, Eric C. D. Tan et al.

• 2013

This report describes one potential conversion process to hydrocarbon products by way of biological conversion of lingnocellulosic-dervied sugars. The process design converts biomass to a hydrocarbon intermediate, a free fatty acid, using dilute-acid pretreatement, enzymatic saccharification, and bioconversion. Ancillary areas--feed handling, hydrolysate conditioning, product recovery and upgrading (hydrotreating) to a final blendstock material, wastewater treatment, lignin combusion, and utilities--are also included in the design.

Jaclyn Demartini, M. Foston, Xianzhi Meng et al.

Biotechnology for Biofuels • 2015

BackgroundWoody biomass is highly recalcitrant to enzymatic sugar release and often requires significant size reduction and severe pretreatments to achieve economically viable sugar yields in biological production of sustainable fuels and chemicals. However, because mechanical size reduction of woody biomass can consume significant amounts of energy, it is desirable to minimize size reduction and instead pretreat larger wood chips prior to biological conversion. To date, however, most laboratory research has been performed on materials that are significantly smaller than applicable in a commercial setting. As a result, there is a limited understanding of the effects that larger biomass particle size has on the effectiveness of steam explosion pretreatment and subsequent enzymatic hydrolysis of wood chips.ResultsTo address these concerns, novel downscaled analysis and high throughput pretreatment and hydrolysis (HTPH) were applied to examine whether differences exist in the composition and digestibility within a single pretreated wood chip due to heterogeneous pretreatment across its thickness. Heat transfer modeling, Simons’ stain testing, magnetic resonance imaging (MRI), and scanning electron microscopy (SEM) were applied to probe the effects of pretreatment within and between pretreated wood samples to shed light on potential causes of variation, pointing to enzyme accessibility (i.e., pore size) distribution being a key factor dictating enzyme digestibility in these samples. Application of these techniques demonstrated that the effectiveness of pretreatment of Populus tremuloides can vary substantially over the chip thickness at short pretreatment times, resulting in spatial digestibility effects and overall lower sugar yields in subsequent enzymatic hydrolysis.ConclusionsThese results indicate that rapid decompression pretreatments (e.g., steam explosion) that specifically alter accessibility at lower temperature conditions are well suited for larger wood chips due to the non-uniformity in temperature and digestibility profiles that can result from high temperature and short pretreatment times. Furthermore, this study also demonstrated that wood chips were hydrated primarily through the natural pore structure during pretreatment, suggesting that preserving the natural grain and transport systems in wood during storage and chipping processes could likely promote pretreatment efficacy and uniformity.

D. P. Maurya, A. Singla, S. Negi

3 Biotech • 2015

Second-generation bioethanol can be produced from various lignocellulosic biomasses such as wood, agricultural or forest residues. Lignocellulosic biomass is inexpensive, renewable and abundant source for bioethanol production. The conversion of lignocellulosic biomass to bioethanol could be a promising technology though the process has several challenges and limitations such as biomass transport and handling, and efficient pretreatment methods for total delignification of lignocellulosics. Proper pretreatment methods can increase concentrations of fermentable sugars after enzymatic saccharification, thereby improving the efficiency of the whole process. Conversion of glucose as well as xylose to bioethanol needs some new fermentation technologies to make the whole process inexpensive. The main goal of pretreatment is to increase the digestibility of maximum available sugars. Each pretreatment process has a specific effect on the cellulose, hemicellulose and lignin fraction; thus, different pretreatment methods and conditions should be chosen according to the process configuration selected for the subsequent hydrolysis and fermentation steps. The cost of ethanol production from lignocellulosic biomass in current technologies is relatively high. Additionally, low yield still remains as one of the main challenges. This paper reviews the various technologies for maximum conversion of cellulose and hemicelluloses fraction to ethanol, and it point outs several key properties that should be targeted for low cost and maximum yield.

Xiaolu Li, Yucai He, Libing Zhang et al.

Biotechnology for Biofuels • 2019

BackgroundBiological routes for utilizing both carbohydrates and lignin are important to reach the ultimate goal of bioconversion of full carbon in biomass into biofuels and biochemicals. Recent biotechnology advances have shown promises toward facilitating biological transformation of lignin into lipids. Natural and engineered Rhodococcus strains (e.g., R. opacus PD630, R. jostii RHA1, and R. jostii RHA1 VanA−) have been demonstrated to utilize lignin for lipid production, and co-culture of them can promote lipid production from lignin.ResultsIn this study, a co-fermentation module of natural and engineered Rhodococcus strains with significant improved lignin degradation and/or lipid biosynthesis capacities was established, which enabled simultaneous conversion of glucose, lignin, and its derivatives into lipids. Although Rhodococci sp. showed preference to glucose over lignin, nearly half of the lignin was quickly depolymerized to monomers by these strains for cell growth and lipid synthesis after glucose was nearly consumed up. Profiles of metabolites produced by Rhodococcus strains growing on different carbon sources (e.g., glucose, alkali lignin, and dilute acid flowthrough-pretreated poplar wood slurry) confirmed lignin conversion during co-fermentation, and indicated novel metabolic capacities and unexplored metabolic pathways in these organisms. Proteome profiles suggested that lignin depolymerization by Rhodococci sp. involved multiple peroxidases with accessory oxidases. Besides the β-ketoadipate pathway, the phenylacetic acid (PAA) pathway was another potential route for the in vivo ring cleavage activity. In addition, deficiency of reducing power and cellular oxidative stress probably led to lower lipid production using lignin as the sole carbon source than that using glucose.ConclusionsThis work demonstrated a potential strategy for efficient bioconversion of both lignin and glucose into lipids by co-culture of multiple natural and engineered Rhodococcus strains. In addition, the involvement of PAA pathway in lignin degradation can help to further improve lignin utilization, and the combinatory proteomics and bioinformatics strategies used in this study can also be applied into other systems to reveal the metabolic and regulatory pathways for balanced cellular metabolism and to select genetic targets for efficient conversion of both lignin and carbohydrates into biofuels.

Leo A Holt, Brian Milligan

Australian Journal of Biological Sciences • 1981

<jats:p>Experiments with the N-benzyloxycarbonyl derivatives of asparagine and glutamine as models show that, in unbuffered solutions, I,I-diacetoxyiodobenzene (1) is more effective than the corresponding trifluoroacetoxy derivative (2) for converting the amide side-chains of proteins to amines. Maximum modification of the glutamine residues of insulin and lysozyme occurs within 1-2 h of treatment with 1 in aqueous methyl cyanide at 20�C, but asparagine residues react more slowly. The amide side-chains are converted to the corresponding amines in at least 90 % yield, as shown by analysis of acid hydrolysates for aspartic acid, lX,p-diaminopropionic acid, glutamic acid and lX,y-diaminobutyric acid. Numerous side-reactions also occur, tyrosine, cystine, methionine, arginine, lysine and N-terminal residues all being modified to some extent.</jats:p>

Vishnu Baba Sundaresan, Stephen Andrew Sarles, Brian J Goode et al.

MRS Proceedings • 2006

<jats:title>ABSTRACT</jats:title><jats:p>Ion transport across cell membranes happens through protein channels and pumps expending concentration gradients, electrical gradients and energy from chemical reactions. Ion exchange in cell membranes is responsible for nutrient transport from production sites to where they are broken down to release energy. Sucrose transport is vital for growth in higher plants and recent research has led to the discovery of a class of sugar carriers called SUT4. The SUT4 transporter is a low affinity, high capacity proton-sucrose transporter that participates in long distance sucrose transport in higher plants. We demonstrated the possibility to use purified SUT4 transporter proteins — with the genetic code from Arabidopsis thaliana expressed on yeast cells — for fluid transport driven by pH gradient and from exergonic ATP hydrolysis reaction in the presence of ATP-ase enzyme. The SUT4 proteins were reconstituted on a planar bilayer lipid membrane formed from 1-Palmitoyl-2-Oleoyl-sn-Glycero-3-[Phospho-L-Serine] (Sodium Salt) (POPS), 1-Palmitoyl-2-Oleoyl-sn-Glycero- 3-Phosphoethanolamine (POPE) phospholipids on a porous substrate. This article builds upon our previous work to harness energy from the ATP-ase reaction using SUT4 to produce a proton current through SUT4 and demonstrates the technical feasibility to generate electrical current in an external circuit. The results from our characterization experiments on a single cell demonstrate that the power source behaves like a constant current power source with an internal resistance of 10-22 kΩ and produces a peak power of 150 nW.</jats:p>

Florent Collas, Beau B. Dronsella, Armin Kubis et al.

• 0

<jats:title>Abstract</jats:title><jats:p>To advance the sustainability of the biobased economy, our society needs to develop novel bioprocesses based on truly renewable resources. The C1-molecule formate is increasingly proposed as carbon and energy source for microbial fermentations, as it can be efficiently generated electrochemically from CO<jats:sub>2</jats:sub>and renewable energy. Yet, its biotechnological conversion into value-added compounds has been limited to a handful of examples. In this work, we engineered the natural formatotrophic bacterium<jats:italic>C. necator</jats:italic>as cell factory to enable biological conversion of formate into crotonate, a platform short-chain unsaturated carboxylic acid of biotechnological relevance. First, we developed a small-scale (150-mL working volume) cultivation setup for growing<jats:italic>C. necator</jats:italic>in minimal medium using formate as only carbon and energy source. By using a fed-batch strategy with automatic feeding of formic acid, we could increase final biomass concentrations 15-fold compared to batch cultivations in flasks. Then, we engineered a heterologous crotonate pathway in the bacterium<jats:italic>via</jats:italic>a modular approach, where each pathway section was assessed using multiple candidates. The best performing modules included a malonyl-CoA bypass for increasing the thermodynamic drive towards the intermediate acetoacetyl-CoA and subsequent conversion to crotonyl-CoA through partial reverse β-oxidation. This pathway architecture was then tested for formate-based biosynthesis in our fed-batch setup, resulting in a two-fold higher titer, three-fold higher productivity, and five-fold higher yield compared to the strain not harboring the bypass. Eventually, we reached a maximum product titer of 148.0 ± 6.8 mg/L. Altogether, this work consists in a proof-of-principle integrating bioprocess and metabolic engineering approaches for the biological upgrading of formate into a value-added platform chemical.</jats:p>

Liesje De Schamphelaire, Willy Verstraete

Biotechnology and Bioengineering • 2009

<jats:title>Abstract</jats:title><jats:p>In the quest for renewable resources, algae are increasingly receiving attention. Their high growth rate, high CO<jats:sub>2</jats:sub> fixation and their lack of requirement for fertile soil surface represent several advantages as compared to conventional (energy) crops. Through their ability to store large amounts of oils, they qualify as a source for biodiesel. Algal biomass, however, can also be used as such, namely as a substrate for anaerobic digestion. In the present research, we investigated the use of algae for energy generation in a stand‐alone, closed‐loop system. The system encompasses an algal growth unit for biomass production, an anaerobic digestion unit to convert the biomass to biogas and a microbial fuel cell to polish the effluent of the digester. Nutrients set free during digestion can accordingly be returned to the algal growth unit for a sustained algal growth. Hence, a system is presented that continuously transforms solar energy into energy‐rich biogas and electricity. Algal productivities of 24–30 ton VS ha<jats:sup>−1</jats:sup> year<jats:sup>−1</jats:sup> were reached, while 0.5 N m<jats:sup>3</jats:sup> biogas could be produced kg<jats:sup>−1</jats:sup> algal VS. The system described resulted in a power plant with a potential capacity of about 9 kW ha<jats:sup>−1</jats:sup> of solar algal panel, with prospects of 23 kW ha<jats:sup>−1</jats:sup>. Biotechnol. Bioeng. 2009;103: 296–304. © 2009 Wiley Periodicals, Inc.</jats:p>

Anqi Ji, Linjing Jia, Deepak Kumar et al.

Fermentation • 0

<jats:p>Sustainable, economically feasible, and green resources for energy and chemical products have people’s attention due to global energy demand and environmental issues. Last several decades, diverse lignocellulosic biomass has been studied for the production of biofuels and biochemicals. Industrial hemp has great market potential with its versatile applications. With the increase of the hemp-related markets with hemp seed, hemp oil, and fiber, the importance of hemp biomass utilization has also been emphasized in recent studies. Biological conversions of industrial hemp into bioethanol and other biochemicals have been introduced to address the aforementioned energy and environmental challenges. Its high cellulose content and the increased production because of the demand for cannabidiol oil and hempseed products make it a promising future bioenergy and biochemical source. Effective valorization of the underutilized hemp biomass can also improve the cost-competitiveness of hemp products. This manuscript reviews recent biological conversion strategies for industrial hemp and its characteristics. Current understanding of the industrial hemp properties and applied conversion technologies are briefly summarized. In addition, challenges and future perspectives of the biological conversion with industrial hemp are discussed.</jats:p>

R. Schönberger

Water Science and Technology • 1990

<jats:p>At the end of 1988 a 22,000 p.e. municipal wastewater treatment plant in Northern Germany was converted to the EASC-biological phosphorus removal process. By simple modifications of the flow scheme of the plant, one of two existing primary clarifiers was converted to an anaerobic basin, into which both sewage and recycle sludge are fed. The supernatant as well as the sludge withdrawn from the bottom are discharged into the aeration basin. This operation mode achieves very good phosphorus uptake in the aeration basin. Since start up in November '88, the uptake-capacity increased continually, since April '89 phosphorus is removed down to concentrations of less than 1 mg/l PO4-P in the aeration basin. Due to an inadequate design and size of the existing final clarifier, phosphorus bleedback occurs and reduces removal efficiency. This bleedback could be minimized by either intensifying denitrification or reducing sludge detention time in the final clarifier.</jats:p>

Xiaoqing Cao, Kai Xia, Hongfei Zhao et al.

Frontiers in Forests and Global Change • 0

<jats:sec><jats:title>Introduction</jats:title><jats:p>Land-use changes significantly impact soil properties in forests, which is an area of concern. Therefore, the effects of changing forest types on soil microbial communities and their functions in northern subtropical forest regions need to be further researched.</jats:p></jats:sec><jats:sec><jats:title>Methods</jats:title><jats:p>We used 16S rDNA sequencing and Functional Annotation of Prokaryotic Taxa (FAPROTAX) to assess the variation of soil bacterial communities and potential functions related to carbon (C) and nitrogen (N) cycling in two soil layers (0–10 and 10–30 cm) after the conversion of the secondary masson pine (<jats:italic>Pinus massoniana</jats:italic>, PM) forest to plantations of slash pine (<jats:italic>Pinus elliottii</jats:italic>, PE) and Chinese fir (<jats:italic>Cunninghamia lanceolata</jats:italic>, CL) located in Jingde County, Anhui Province, China.</jats:p></jats:sec><jats:sec><jats:title>Results</jats:title><jats:p>The study found that converting coniferous secondary forests to coniferous plantations resulted in a notable increase in soil pH and a decrease in nitrate nitrogen and organic carbon contents. Additionally, soil microbial diversity increased significantly, and microbial community structure changed, particularly in the topsoil. These changes might affect the C- and N-cycling mediated by soil bacteria. The analysis revealed a significant decrease in the abundance of functional groups associated with C-cycling and a significant increase in the abundance of functional groups associated with N-cycling, particularly those associated with denitrification. Soil organic carbon, pH, and ammonium nitrogen were the most critical variables affecting changes in the soil microbial community.</jats:p></jats:sec><jats:sec><jats:title>Discussion</jats:title><jats:p>These findings provide valuable information for ecological restoration and future sustainable forest management.</jats:p></jats:sec>

Ahmed K. Saleh, Emad Tolba, Ahmed Salama

Biomass Conversion and Biorefinery • 2024

<jats:title>Abstract</jats:title><jats:p>Bacterial cellulose (BC) has garnered attention among biomaterial scientists for its unique physicochemical features and biocompatibility; however, the lack of bioactivity has limited its biomedical applications. Thus, this study describes the in situ preparation of BC/hydroxyapatite (HA) nanocomposite membranes using static and agitated fermentation to enhance the bioactivity of BC. The incorporation of HA increased BC production from 2.31 g/L without HA to 4.10 and 3.26 g/L under static and agitated fermentation, respectively, although the SEM observation indicates the formation of a fibrous structure in BC mesh under both fermentations. It was also observed that the content of HA nanoparticles in BC obtained from agitated fermentation was higher than that obtained from static fermentation. In addition, the average fiber diameter was increased from 56 ± 17 nm for agitated nanocomposites (BC/HA-A) to 145 ± 48 nm for static BC/HA nanocomposites (BC/HA-S) and 122 ± 26 nm for BC. In conclusion, the in situ formation of BC/HA nanocomposite under agitated fermentation appears more convenient in term of BC yield, HA content and distribution, and cytotoxicity against fibroblast cells (BJ1). This strategy will inspire new ways to prepare BC-based materials for medical applications.</jats:p>

Roland H. Müller, Thore Rohwerder, Hauke Harms

Applied and Environmental Microbiology • 2007

<jats:title>ABSTRACT</jats:title> <jats:p> The utilization of the fuel oxygenate methyl <jats:italic>tert</jats:italic> -butyl ether (MTBE) and related compounds by microorganisms was investigated in a mainly theoretical study based on the Y <jats:sub>ATP</jats:sub> concept. Experiments were conducted to derive realistic maintenance coefficients and <jats:italic>K</jats:italic> <jats:sub> <jats:italic>s</jats:italic> </jats:sub> values needed to calculate substrate fluxes available for biomass production. Aerobic substrate conversion and biomass synthesis were calculated for different putative pathways. The results suggest that MTBE is an effective heterotrophic substrate that can sustain growth yields of up to 0.87 g g <jats:sup>−1</jats:sup> , which contradicts previous calculation results (N. Fortin et al., Environ. Microbiol. 3:407-416, 2001). Sufficient energy equivalents were generated in several of the potential assimilatory routes to incorporate carbon into biomass without the necessity to dissimilate additional substrate, efficient energy transduction provided. However, when a growth-related kinetic model was included, the limits of productive degradation became obvious. Depending on the maintenance coefficient <jats:italic>m</jats:italic> <jats:sub> <jats:italic>s</jats:italic> </jats:sub> and its associated biomass decay term <jats:italic>b</jats:italic> , growth-associated carbon conversion became strongly dependent on substrate fluxes. Due to slow degradation kinetics, the calculations predicted relatively high threshold concentrations, <jats:italic>S</jats:italic> <jats:sub>min</jats:sub> , below which growth would not further be supported. <jats:italic>S</jats:italic> <jats:sub>min</jats:sub> strongly depended on the maximum growth rate <jats:italic>μ</jats:italic> <jats:sub>ma</jats:sub> <jats:sub> <jats:italic>x</jats:italic> </jats:sub> , and <jats:italic>b</jats:italic> and was directly correlated with the half maximum rate-associated substrate concentration <jats:italic>K</jats:italic> <jats:sub> <jats:italic>s</jats:italic> </jats:sub> , meaning that any effect impacting this parameter would also change <jats:italic>S</jats:italic> <jats:sub>min</jats:sub> . The primary metabolic step, catalyzing the cleavage of the ether bond in MTBE, is likely to control the substrate flux in various strains. In addition, deficits in oxygen as an external factor and in reduction equivalents as a cellular variable in this reaction should further increase <jats:italic>K</jats:italic> <jats:sub> <jats:italic>s</jats:italic> </jats:sub> and <jats:italic>S</jats:italic> <jats:sub>min</jats:sub> for MTBE. </jats:p>