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Chemosphere Nov 2021This is the first study to bring evidence on the anaerobic biodegradation of TBBPA occurring during acidogenesis in domestic sewage at environmentally relevant...
This is the first study to bring evidence on the anaerobic biodegradation of TBBPA occurring during acidogenesis in domestic sewage at environmentally relevant concentrations by complex microbial communities. This was accomplished by continuously operating two anaerobic structured bed reactors (ASTBR) for over 100 days under acidogenic (Acidogenic Reactor, AR) and multistep methanogenic (Methanogenic Reactor, MR) conditions. In the AR, the temporal carbohydrates consumption and the acetic acid production were strongly correlated with TBBPA removal by the Pearson's test. The spatial concentration of TBBPA and carbohydrates along the MR and the kinetic degradation profiles corroborate the AR results. It is hypothesized that TBBPA biodegradation in the studied conditions occurs during acidogenesis via the cometabolism supported by non-specific enzymes and the metabolism (dehalorespiration) established by electrons donors such as H, which are both produced during the macrocomponents breakdown in the early stages of the anaerobic digestion. The TBBPA mass balance showed that approximately 86.8 ± 0.05% and 97 ± 0.01% of the removed TBBPA was biodegraded in the AR and MR, respectively. Furthermore, TBBPA biodegradation went further than reductive debromination as total phenols were detected in the reactors' effluent.
Topics: Anaerobiosis; Biodegradation, Environmental; Polybrominated Biphenyls; Sewage
PubMed: 34116313
DOI: 10.1016/j.chemosphere.2021.130995 -
Bioengineered Mar 2022In the past decades, considerable attention has been directed toward anaerobic digestion (AD), which is an effective biological process for converting diverse organic... (Review)
Review
In the past decades, considerable attention has been directed toward anaerobic digestion (AD), which is an effective biological process for converting diverse organic wastes into biogas, volatile fatty acids (VFAs), biohydrogen, etc. The microbial bioprocessing takes part during AD is of substantial significance, and one of the crucial approaches for the deep and adequate understanding and manipulating it toward different products is process microbiology. Due to highly complexity of AD microbiome, it is critically important to study the involved microorganisms in AD. In recent years, in addition to traditional methods, novel molecular techniques and meta-omics approaches have been developed which provide accurate details about microbial communities involved AD. Better understanding of process microbiomes could guide us in identifying and controlling various factors in both improving the AD process and diverting metabolic pathway toward production of selective bio-products. This review covers various platforms of AD process that results in different final products from microbiological point of view. The review also highlights distinctive interactions occurring among microbial communities. Furthermore, assessment of these communities existing in the anaerobic digesters is discussed to provide more insights into their structure, dynamics, and metabolic pathways. Moreover, the important factors affecting microbial communities in each platform of AD are highlighted. Finally, the review provides some recent applications of AD for the production of novel bio-products and deals with challenges and future perspectives of AD.
Topics: Anaerobiosis; Biofuels; Bioreactors; Fatty Acids, Volatile; Hydrogen; Microbiota
PubMed: 35212604
DOI: 10.1080/21655979.2022.2035986 -
Critical Reviews in Biotechnology Jun 2022Anaerobic digestion (AD) for biogas production is affected by many factors that includes organic loading rate (OLR). This OLR appears to be closely linked to various... (Review)
Review
Anaerobic digestion (AD) for biogas production is affected by many factors that includes organic loading rate (OLR). This OLR appears to be closely linked to various other factors and understanding these linkages would therefore allow the sole use of OLR for process performance monitoring, control, as well as reactor design. This review's objective is to collate the various AD factor specific studies, then relate these factors' role in OLR fluctuations. By further analyzing the influence of OLR on the AD performance, it would then be possible, once all the other factors have been determined and fixed, to manage an AD plant by monitoring and controlling OLR only. Decisions on reactor design, process kinetics, biogas yield and process stability can then be made much more quickly and with minimal troubleshooting steps.
Topics: Anaerobiosis; Biofuels; Bioreactors; Methane
PubMed: 34315294
DOI: 10.1080/07388551.2021.1942778 -
Bioresource Technology Feb 2022Hybrid microbial electrolysis cells-anaerobic digestion (MEC-AD) was proved to increase methane productivity and methane yield of waste activated sludge (WAS) by... (Review)
Review
Hybrid microbial electrolysis cells-anaerobic digestion (MEC-AD) was proved to increase methane productivity and methane yield of waste activated sludge (WAS) by establishing direct interspecies electron transfer method and enriching functional microorganisms. This review first summarized the pretreatment methods of WAS for MEC-AD and then reviewed the reactor configurations, operation parameters, and the economic benefit of MEC-AD. Furthermore, the enhancement mechanisms of MEC-AD were reviewed based on the analysis of thermodynamics and microbial community. It was found that the decrease of hydrogen partial pressure due to the hydrogenotrophic methanogens enriched in cathodic biofilm and direct interspecies electron transfer between exoelectrogens and anode were the core mechanisms for improving acidogenesis, acetogenesis, and methanogenesis. Finally, the potentially technological issues that need to be addressed to increase energy efficiency in large-scale MEC-AD processes were discussed.
Topics: Anaerobiosis; Bioreactors; Electrolysis; Methane; Sewage
PubMed: 34973405
DOI: 10.1016/j.biortech.2021.126641 -
Bioresource Technology Jan 2022Medium-chain carboxylic acid (MCCA) production from organic wastes has attracted much attention because of their higher energy contents and diverse applications.... (Review)
Review
Metabolic cascade of complex organic wastes to medium-chain carboxylic acids: A review on the state-of-the-art multi-omics analysis for anaerobic chain elongation pathways.
Medium-chain carboxylic acid (MCCA) production from organic wastes has attracted much attention because of their higher energy contents and diverse applications. Anaerobic reactor microbiomes are stable and resilient and have resulted in efficient performance during many years of operation for thousands of full-scale anaerobic digesters worldwide. The method underlying how the relevant microbial pathways contribute to elongate carbon chains in reactor microbiomes is important. In particular, the reverse β-oxidation pathway genes are critical to upgrading short-chain fermentation products to MCCAs via a chain elongation (CE) process. Diverse genomics and metagenomics studies have been conducted in various fields, ranging from intracellular metabolic pathways to metabolic cascades between different strains. This review covers taxonomic approach to culture processes depending on types of organic wastes and the deeper understanding of genome and metagenome-scale CE pathway construction, and the co-culture and multi-omics technology that should be addressed in future research.
Topics: Anaerobiosis; Bioreactors; Carboxylic Acids; Fermentation; Microbiota
PubMed: 34710599
DOI: 10.1016/j.biortech.2021.126211 -
MBio Jun 2021Anaerobic fungi () isolated from the guts of herbivores are powerful biomass-degrading organisms that enhance their degradative ability through the formation of...
Anaerobic fungi () isolated from the guts of herbivores are powerful biomass-degrading organisms that enhance their degradative ability through the formation of cellulosomes, multienzyme complexes that synergistically colocalize enzymes to extract sugars from recalcitrant plant matter. However, a functional understanding of how fungal cellulosomes are deployed to orchestrate plant matter degradation is lacking, as is knowledge of how cellulosome production and function vary throughout the morphologically diverse life cycle of anaerobic fungi. In this work, we generated antibodies against three major fungal cellulosome protein domains, a dockerin, scaffoldin, and glycoside hydrolase (GH) 48 protein, and used them in conjunction with helium ion and immunofluorescence microscopy to characterize cellulosome localization patterns throughout the life cycle of Piromyces finnis when grown on simple sugars and complex cellulosic carbon sources. Our analyses reveal that fungal cellulosomes are cell-localized entities specifically targeted to the rhizoids of mature fungal cells and bodies of zoospores. Examination of cellulosome localization patterns across life stages also revealed that cellulosome production is independent of growth substrate in zoospores but repressed by simple sugars in mature cells. This suggests that further exploration of gene regulation patterns in zoospores is needed and can inform potential strategies for derepressing cellulosome expression and boosting hydrolytic enzyme yields from fungal cultures. Collectively, these findings underscore how life cycle-dependent cell morphology and regulation of cellulosome production impact biomass degradation by anaerobic fungi, insights that will benefit ongoing efforts to develop these organisms and their cellulosomes into platforms for converting waste biomass into valuable bioproducts. Anaerobic fungi () isolated from the guts of herbivores excel at degrading ingested plant matter, making them attractive potential platform organisms for converting waste biomass into valuable products, such as chemicals and fuels. Major contributors to their biomass-hydrolyzing power are the multienzyme cellulosome complexes that anaerobic fungi produce, but knowledge gaps in how cellulosome production is controlled by the cellular life cycle and how cells spatially deploy cellulosomes complicate the use of anaerobic fungi and their cellulosomes in industrial bioprocesses. We developed and used imaging tools to observe cellulosome spatial localization patterns across life stages of the anaerobic fungus under different environmental conditions. The resulting spatial details of how anaerobic fungi orchestrate biomass degradation and uncovered relationships between life cycle progression and regulation of cellulosome production will benefit ongoing efforts to develop anaerobic fungi and their cellulosomes into useful biomass-upgrading platforms.
Topics: Anaerobiosis; Biomass; Cellulosomes; Hydrolysis; Piromyces
PubMed: 34061594
DOI: 10.1128/mBio.00832-21 -
The Science of the Total Environment Apr 2021Anaerobic digestion (AD) is a widely applied technology for treating organic wastes to generate renewable energy in the form of biogas. The effectiveness of AD process... (Review)
Review
Anaerobic digestion (AD) is a widely applied technology for treating organic wastes to generate renewable energy in the form of biogas. The effectiveness of AD process depends on many factors, among which the most important is the presence of active and healthy microbial community in the anaerobic digesters, which needs to be explored. However, the deciphering of microbial populations and their functions during the AD process of different materials is still incomplete, which restricts the understanding of its long-term performance under different operational conditions. This review describes the type, morphology, functions, and specific growth conditions of commonly found hydrolytic, acidogenic, acetogenic bacteria, and archaea during the AD process. The effects of microbes on the performance and stability of the digestion process are also presented. Furthermore, the article offers a deep understanding of the AD management strategies for the enhancement of methane production and the efficiency of the energy conversion process of various organic wastes.
Topics: Anaerobiosis; Archaea; Bacteria; Biofuels; Bioreactors; Methane
PubMed: 33229086
DOI: 10.1016/j.scitotenv.2020.143007 -
Environmental Microbiology Reports Oct 2022
Topics: Anaerobiosis; Denitrification; Methane; Nitrites; Oxidation-Reduction
PubMed: 35944518
DOI: 10.1111/1758-2229.13114 -
Biotechnology Advances Oct 2023The wide application of anaerobic digestion (AD) technology is limited by process fluctuations. Thus, process monitoring based on screening state parameters as early... (Review)
Review
The wide application of anaerobic digestion (AD) technology is limited by process fluctuations. Thus, process monitoring based on screening state parameters as early warning indicators (EWI) is a top priority for AD facilities. However, predicting anaerobic digester stability based on such indicators is difficult, and their threshold values are uncertain, case-specific, and sometimes produce conflicting results. Thus, new EWI should be proposed to integrate microbial and metabolic information. These microbial volatile organic compounds (mVOCs) including alkanes, alkenes, alkynes, aromatic compounds are produced by microorganisms (bacteria, archaea and fungi), which might serve as a promising diagnostic tool for environmental monitoring. Moreover, mVOCs diffuse in both gas and liquid phases and are considered the language of intra kingdom microbial interactions. Herein, we highlight the potential of mVOCs as EWI for AD process instability, including discussions regarding characteristics and sources of mVOCs as well as sampling and determination methods. Furthermore, existing challenges must be addressed, before mVOCs profiling can be used as an early warning system for diagnosing AD process instability, such as mVOCs sampling, analysis and identification. Finally, we discuss the potential biotechnology applications of mVOCs and approaches to overcome the challenges regarding their application.
Topics: Volatile Organic Compounds; Anaerobiosis; Fungi; Bacteria; Archaea
PubMed: 37356597
DOI: 10.1016/j.biotechadv.2023.108204 -
Bioresource Technology Jul 2021Microalgae is considered as a renewable and sustainable biomass to produce bioenergy and other high-value products. Besides, the cultivation of microalgae does not need... (Review)
Review
Microalgae is considered as a renewable and sustainable biomass to produce bioenergy and other high-value products. Besides, the cultivation of microalgae does not need any fertile land and it provides opportunities for climate change mitigation by sequestering atmospheric carbon-dioxide (CO), facilitating nutrient recovery from wastewater and regulating industrial pollutions/emissions. Algal biomass harvested from different technologies are unique in their physio-chemical properties that require critical understanding prior to value-addition or bioenergy recovery. In this review, we elaborate the importance of cell wall weakening followed by pretreatment as a key process step and strategy to reduce the energy cost of converting algal biomass into bioenergy. From the energy-calculations, it was measured that the cell wall weakening significantly improves the net-energy ratio from 0.68 to 1.02. This approach could be integrated with any pre-treatment options, while it reduces the time of pre-treatment and costs of energy/chemicals required for hydrolysis of algal biomass.
Topics: Anaerobiosis; Biofuels; Biomass; Cost-Benefit Analysis; Microalgae
PubMed: 33813179
DOI: 10.1016/j.biortech.2021.125055