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Qiu S, Zhang X, Xia W, Li Z, Wang L, Chen Z, Ge S. Effect of extreme pH conditions on methanogenesis: Methanogen metabolism and community structure. THE SCIENCE OF THE TOTAL ENVIRONMENT 2023; 877:162702. [PMID: 36898547 DOI: 10.1016/j.scitotenv.2023.162702] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/07/2022] [Revised: 03/03/2023] [Accepted: 03/03/2023] [Indexed: 05/06/2023]
Abstract
The control of pH is effective for inhibiting methanogenesis in the chain elongation fermentation (CEF) system. However, obscure conclusions exist especially with regard to the underlying mechanism. This study comprehensively explored the responses of methanogenesis in granular sludge at various pH levels, ranging from 4.0 to 10.0, from multiple aspects including methane production, methanogenesis pathway, microbial community structure, energy metabolism and electron transport. Results demonstrated that compared with that at pH 7.0, pH at 4.0, 5.5, 8.5 and 10.0 triggered a 100%, 71.7%, 23.8% and 92.1% suppression on methanogenesis by the end of 3 cycles lasting 21 days. This might be explained by the remarkably inhibited metabolic pathways and intracellular regulations. To be more specific, extreme pH conditions decreased the abundance of the acetoclastic methanogens. However, obligate hydrogenotrophic and facultative acetolactic/hydrogenotrophic methanogens were significantly enriched by 16.9%-19.5 fold. pH stress reduced the gene abundance and/or activity of most enzymes involved in methanogenesis such as acetate kinase (by 81.1%-93.1%), formylmethanofuran dehydrogenase (by 10.9%-54.0%) and tetrahydromethanopterin S-methyltransferase (by 9.3%-41.5%). Additionally, pH stress suppressed electron transport via improper electron carriers and decreased electron amount as evidenced by 46.3%-70.4% reduced coenzyme F420 content and diminished abundance of CO dehydrogenase (by 15.5%-70.5%) and NADH:ubiquinone reductase (by 20.2%-94.5%). pH stress also regulated energy metabolism with inhibited ATP synthesis (e.g., ATP citrate synthase level reduced by 20.1%-95.3%). Interestingly, the protein and carbohydrate content secreted in EPS failed to show consistent responses to acidic and alkaline conditions. Specifically, when compared with pH 7.0, the acidic condition remarkably reduced the levels of total EPS and EPS protein while both levels were enhanced in the alkaline condition. However, the EPS carbohydrate content at pH 4.0 and 10.0 both decreased. This study is expected to promote the understanding of the pH control-induced methanogenesis inhibition in the CEF system.
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Affiliation(s)
- Shuang Qiu
- Jiangsu Key Laboratory of Chemical Pollution Control and Resources Reuse, School of Environmental and Biological Engineering, Nanjing University of Science and Technology, Xiao Ling Wei 200, Nanjing 210094, Jiangsu, China
| | - Xingchen Zhang
- Jiangsu Key Laboratory of Chemical Pollution Control and Resources Reuse, School of Environmental and Biological Engineering, Nanjing University of Science and Technology, Xiao Ling Wei 200, Nanjing 210094, Jiangsu, China
| | - Wenhao Xia
- Jiangsu Key Laboratory of Chemical Pollution Control and Resources Reuse, School of Environmental and Biological Engineering, Nanjing University of Science and Technology, Xiao Ling Wei 200, Nanjing 210094, Jiangsu, China
| | - Zimu Li
- Jiangsu Key Laboratory of Chemical Pollution Control and Resources Reuse, School of Environmental and Biological Engineering, Nanjing University of Science and Technology, Xiao Ling Wei 200, Nanjing 210094, Jiangsu, China
| | - Lingfeng Wang
- Jiangsu Key Laboratory of Chemical Pollution Control and Resources Reuse, School of Environmental and Biological Engineering, Nanjing University of Science and Technology, Xiao Ling Wei 200, Nanjing 210094, Jiangsu, China
| | - Zhipeng Chen
- Jiangsu Key Laboratory of Chemical Pollution Control and Resources Reuse, School of Environmental and Biological Engineering, Nanjing University of Science and Technology, Xiao Ling Wei 200, Nanjing 210094, Jiangsu, China
| | - Shijian Ge
- Jiangsu Key Laboratory of Chemical Pollution Control and Resources Reuse, School of Environmental and Biological Engineering, Nanjing University of Science and Technology, Xiao Ling Wei 200, Nanjing 210094, Jiangsu, China.
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Montoya ACV, da Silva Mazareli RC, Delforno TP, Centurion VB, de Oliveira VM, Silva EL, Varesche MBA. New Insights into Controlling Homoacetogenesis in the Co-digestion of Coffee Waste: Effect of Operational Conditions and Characterization of Microbial Communities. Appl Biochem Biotechnol 2021; 194:1458-1478. [PMID: 34739703 DOI: 10.1007/s12010-021-03725-3] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2021] [Accepted: 10/08/2021] [Indexed: 11/29/2022]
Abstract
In this research batch reactors were operated with coffee processing waste and autochthonous microbial consortium, and a taxonomic and functional analysis was performed for phase I of stabilization of maximum H2 production and for phase II of maximum H2 consumption. During phase I, the reactor's operating conditions were pH 4.84 to 8.18, headspace 33.18% to 66.82%, and pulp and husk from 6.95 to 17.05 g/L. These assays continued for phase II, with initial pH conditions of 5.8-8.1, headspace of 33.18-66.82%, and pulp and husk remaining from phase I. The highest homoacetogenesis was observed in assay 5 with pH 7.7, 40% headspace, and 15 g/L of pulp and husk (initial concentrations of phase I). A relative abundance of Clostridium 41%, Lactobacillus 20% and Acetobacter 14% was observed in phase I. In phase II, there was a change in relative abundance of 21%, 63%, and 1%, respectively, and functional genes involved with autotrophic (formyltetrahydrofolate synthase) and heterotrophic (enolase) homoacetogenesis, butanol (3-hydroxybutyryl-CoA dehydrogenase), and propionic acid (propionate CoA-transferase) were identified. This study provides a new and amplified insight into the physicochemical and microbiological factors, which can be used to propose adequate operational conditions to maximize the bioenergy production and reduce homoacetogenesis in biological reactors.
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Affiliation(s)
- Alejandra Carolina Villa Montoya
- Laboratory of Biological Processes, Department of Hydraulics and Sanitation, São Carlos School of Engineering, University of São Paulo, Campus II, São Carlos, SP, CEP 13563-120, Brazil.
| | - Raissa Cristina da Silva Mazareli
- Laboratory of Biological Processes, Department of Hydraulics and Sanitation, São Carlos School of Engineering, University of São Paulo, Campus II, São Carlos, SP, CEP 13563-120, Brazil
| | | | - Victor Borin Centurion
- Microbial Resources Division, Research Center for Chemistry, Biology and Agriculture (CPQBA), State University of Campinas, Campinas, SP, CEP 13081-970, Brazil
| | - Valéria Maia de Oliveira
- Microbial Resources Division, Research Center for Chemistry, Biology and Agriculture (CPQBA), State University of Campinas, Campinas, SP, CEP 13081-970, Brazil
| | - Edson Luiz Silva
- Center of Exact Sciences and Technology, Department of Chemical Engineering, Federal University of São Carlos, São Carlos, SP, CEP 13565-905, Brazil
| | - Maria Bernadete Amâncio Varesche
- Laboratory of Biological Processes, Department of Hydraulics and Sanitation, São Carlos School of Engineering, University of São Paulo, Campus II, São Carlos, SP, CEP 13563-120, Brazil.
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Liu T, Ou H, Su K, Hu Z, He C, Wang W. Promoting direct interspecies electron transfer and acetoclastic methanogenesis for enhancing anaerobic digestion of butanol octanol wastewater by coupling granular activated carbon and exogenous hydrogen. BIORESOURCE TECHNOLOGY 2021; 337:125417. [PMID: 34166933 DOI: 10.1016/j.biortech.2021.125417] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/13/2021] [Revised: 06/09/2021] [Accepted: 06/11/2021] [Indexed: 06/13/2023]
Abstract
Butanol octanol wastewater (BOW) generated from syngas conversion of coal contained abundant toxic organic pollutants. Anaerobic digestion is a promising technology for BOW, but abundant toxic substances would inhibit the activity of anaerobic microorganisms. Granular activated carbon (GAC) and exogenous hydrogen (EH2) were employed to enhance anaerobic digestion of BOW. The results indicated that methane production increased to 289.55 ± 17.43 mL CH4/g COD in EH2/GAC group, which was 1.07, 2.04, and 1.98 times of that in GAC, EH2, and control groups, respectively. In EH2/GAC group. The relative abundance of Geobacter and Methanosaeta increased rapidly to 25.36% and 52.81%, respectively, and the relative abundance of Clostridium was 9.78%. The underlying mechanism might be that GAC promoted the enrichment of Geobacter, and EH2 changed metabolic mechanism of Clostridium, stimulating the enrichment of Methanosaeta. Direct interspecies electron transfer was promoted by EH2/GAC, thus improving the methane production rate of BOW.
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Affiliation(s)
- Tingxia Liu
- Department of Municipal Engineering, School of Civil Engineering, Hefei University of Technology, Hefei 230009, China; Anhui Provincial Engineering Laboratory for Rural Water Environment and Resources, Hefei 230009, China; Anhui Province Key Laboratory of Industrial Wastewater and Environmental Treatment, Hefei 230024, China
| | - Hua Ou
- Department of Municipal Engineering, School of Civil Engineering, Hefei University of Technology, Hefei 230009, China; Anhui Provincial Engineering Laboratory for Rural Water Environment and Resources, Hefei 230009, China; Anhui Province Key Laboratory of Industrial Wastewater and Environmental Treatment, Hefei 230024, China
| | - Kuizu Su
- Department of Municipal Engineering, School of Civil Engineering, Hefei University of Technology, Hefei 230009, China; Anhui Provincial Engineering Laboratory for Rural Water Environment and Resources, Hefei 230009, China; Anhui Province Key Laboratory of Industrial Wastewater and Environmental Treatment, Hefei 230024, China
| | - Zhenhu Hu
- Department of Municipal Engineering, School of Civil Engineering, Hefei University of Technology, Hefei 230009, China; Anhui Provincial Engineering Laboratory for Rural Water Environment and Resources, Hefei 230009, China; Anhui Province Key Laboratory of Industrial Wastewater and Environmental Treatment, Hefei 230024, China
| | - Chunhua He
- Department of Municipal Engineering, School of Civil Engineering, Hefei University of Technology, Hefei 230009, China; Anhui Provincial Engineering Laboratory for Rural Water Environment and Resources, Hefei 230009, China; Anhui Province Key Laboratory of Industrial Wastewater and Environmental Treatment, Hefei 230024, China.
| | - Wei Wang
- Department of Municipal Engineering, School of Civil Engineering, Hefei University of Technology, Hefei 230009, China; Anhui Provincial Engineering Laboratory for Rural Water Environment and Resources, Hefei 230009, China; Anhui Province Key Laboratory of Industrial Wastewater and Environmental Treatment, Hefei 230024, China
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4
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Singh A, Müller B, Schnürer A. Profiling temporal dynamics of acetogenic communities in anaerobic digesters using next-generation sequencing and T-RFLP. Sci Rep 2021; 11:13298. [PMID: 34168213 PMCID: PMC8225771 DOI: 10.1038/s41598-021-92658-2] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2021] [Accepted: 06/14/2021] [Indexed: 02/06/2023] Open
Abstract
Acetogens play a key role in anaerobic degradation of organic material and in maintaining biogas process efficiency. Profiling this community and its temporal changes can help evaluate process stability and function, especially under disturbance/stress conditions, and avoid complete process failure. The formyltetrahydrofolate synthetase (FTHFS) gene can be used as a marker for acetogenic community profiling in diverse environments. In this study, we developed a new high-throughput FTHFS gene sequencing method for acetogenic community profiling and compared it with conventional terminal restriction fragment length polymorphism of the FTHFS gene, 16S rRNA gene-based profiling of the whole bacterial community, and indirect analysis via 16S rRNA profiling of the FTHFS gene-harbouring community. Analyses and method comparisons were made using samples from two laboratory-scale biogas processes, one operated under stable control and one exposed to controlled overloading disturbance. Comparative analysis revealed satisfactory detection of the bacterial community and its changes for all methods, but with some differences in resolution and taxonomic identification. FTHFS gene sequencing was found to be the most suitable and reliable method to study acetogenic communities. These results pave the way for community profiling in various biogas processes and in other environments where the dynamics of acetogenic bacteria have not been well studied.
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Affiliation(s)
- Abhijeet Singh
- grid.6341.00000 0000 8578 2742Anaerobic Microbiology and Biotechnology Group, Department of Molecular Sciences, Swedish University of Agricultural Sciences, Almas Allé 5, Box 7025, 750 07 Uppsala, Sweden
| | - Bettina Müller
- grid.6341.00000 0000 8578 2742Anaerobic Microbiology and Biotechnology Group, Department of Molecular Sciences, Swedish University of Agricultural Sciences, Almas Allé 5, Box 7025, 750 07 Uppsala, Sweden
| | - Anna Schnürer
- grid.6341.00000 0000 8578 2742Anaerobic Microbiology and Biotechnology Group, Department of Molecular Sciences, Swedish University of Agricultural Sciences, Almas Allé 5, Box 7025, 750 07 Uppsala, Sweden
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Contreras-Dávila CA, Esveld J, Buisman CJN, Strik DPBTB. nZVI Impacts Substrate Conversion and Microbiome Composition in Chain Elongation From D- and L-Lactate Substrates. Front Bioeng Biotechnol 2021; 9:666582. [PMID: 34211964 PMCID: PMC8239352 DOI: 10.3389/fbioe.2021.666582] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2021] [Accepted: 05/25/2021] [Indexed: 12/12/2022] Open
Abstract
Medium-chain carboxylates (MCC) derived from biomass biorefining are attractive biochemicals to uncouple the production of a wide array of products from the use of non-renewable sources. Biological conversion of biomass-derived lactate during secondary fermentation can be steered to produce a variety of MCC through chain elongation. We explored the effects of zero-valent iron nanoparticles (nZVI) and lactate enantiomers on substrate consumption, product formation and microbiome composition in batch lactate-based chain elongation. In abiotic tests, nZVI supported chemical hydrolysis of lactate oligomers present in concentrated lactic acid. In fermentation experiments, nZVI created favorable conditions for either chain-elongating or propionate-producing microbiomes in a dose-dependent manner. Improved lactate conversion rates and n-caproate production were promoted at 0.5-2 g nZVI⋅L-1 while propionate formation became relevant at ≥ 3.5 g nZVI⋅L-1. Even-chain carboxylates (n-butyrate) were produced when using enantiopure and racemic lactate with lactate conversion rates increased in nZVI presence (1 g⋅L-1). Consumption of hydrogen and carbon dioxide was observed late in the incubations and correlated with acetate formation or substrate conversion to elongated products in the presence of nZVI. Lactate racemization was observed during chain elongation while isomerization to D-lactate was detected during propionate formation. Clostridium luticellarii, Caproiciproducens, and Ruminococcaceae related species were associated with n-valerate and n-caproate production while propionate was likely produced through the acrylate pathway by Clostridium novyi. The enrichment of different potential n-butyrate producers (Clostridium tyrobutyricum, Lachnospiraceae, Oscillibacter, Sedimentibacter) was affected by nZVI presence and concentrations. Possible theories and mechanisms underlying the effects of nZVI on substrate conversion and microbiome composition are discussed. An outlook is provided to integrate (bio)electrochemical systems to recycle (n)ZVI and provide an alternative reducing power agent as durable control method.
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Affiliation(s)
| | - Johan Esveld
- Environmental Technology, Wageningen University & Research, Wageningen, Netherlands
| | - Cees J N Buisman
- Environmental Technology, Wageningen University & Research, Wageningen, Netherlands
| | - David P B T B Strik
- Environmental Technology, Wageningen University & Research, Wageningen, Netherlands
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6
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Prem EM, Mutschlechner M, Stres B, Illmer P, Wagner AO. Lignin intermediates lead to phenyl acid formation and microbial community shifts in meso- and thermophilic batch reactors. BIOTECHNOLOGY FOR BIOFUELS 2021; 14:27. [PMID: 33472684 PMCID: PMC7816434 DOI: 10.1186/s13068-020-01855-0] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/17/2020] [Accepted: 12/09/2020] [Indexed: 05/10/2023]
Abstract
BACKGROUND Lignin intermediates resulting from lignocellulose degradation have been suspected to hinder anaerobic mineralisation of organic materials to biogas. Phenyl acids like phenylacetate (PAA) are early detectable intermediates during anaerobic digestion (AD) of aromatic compounds. Studying the phenyl acid formation dynamics and concomitant microbial community shifts can help to understand the microbial interdependencies during AD of aromatic compounds and may be beneficial to counteract disturbances. RESULTS The length of the aliphatic side chain and chemical structure of the benzene side group(s) had an influence on the methanogenic system. PAA, phenylpropionate (PPA), and phenylbutyrate (PBA) accumulations showed that the respective lignin intermediate was degraded but that there were metabolic restrictions as the phenyl acids were not effectively processed. Metagenomic analyses confirmed that mesophilic genera like Fastidiosipila or Syntrophomonas and thermophilic genera like Lactobacillus, Bacillus, Geobacillus, and Tissierella are associated with phenyl acid formation. Acetoclastic methanogenesis was prevalent in mesophilic samples at low and medium overload conditions, whereas Methanoculleus spp. dominated at high overload conditions when methane production was restricted. In medium carbon load reactors under thermophilic conditions, syntrophic acetate oxidation (SAO)-induced hydrogenotrophic methanogenesis was the most important process despite the fact that acetoclastic methanogenesis would thermodynamically be more favourable. As acetoclastic methanogens were restricted at medium and high overload conditions, syntrophic acetate oxidising bacteria and their hydrogenotrophic partners could step in for acetate consumption. CONCLUSIONS PAA, PPA, and PBA were early indicators for upcoming process failures. Acetoclastic methanogens were one of the first microorganisms to be impaired by aromatic compounds, and shifts to syntrophic acetate oxidation coupled to hydrogenotrophic methanogenesis occurred in thermophilic reactors. Previously assumed associations of specific meso- and thermophilic genera with anaerobic phenyl acid formation could be confirmed.
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Affiliation(s)
- Eva Maria Prem
- Department of Microbiology, Universität Innsbruck, Technikerstraße 25d, 6020, Innsbruck, Austria.
| | - Mira Mutschlechner
- Department of Microbiology, Universität Innsbruck, Technikerstraße 25d, 6020, Innsbruck, Austria
| | - Blaz Stres
- Department of Animal Science, Biotechnical Faculty, University of Ljubljana, Jamnikarjeva 101, 1000, Ljubljana, Slovenia
- Institute of Sanitary Engineering, Faculty of Civil and Geodetic Engineering, University of Ljubljana, Jamova 2, 1000, Ljubljana, Slovenia
- Department of Automation, Biocybernetics and Robotics, Jozef Štefan Institute, Jamova 39, 1000, Ljubljana, Slovenia
| | - Paul Illmer
- Department of Microbiology, Universität Innsbruck, Technikerstraße 25d, 6020, Innsbruck, Austria
| | - Andreas Otto Wagner
- Department of Microbiology, Universität Innsbruck, Technikerstraße 25d, 6020, Innsbruck, Austria
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7
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Liu T, Schnürer A, Björkmalm J, Willquist K, Kreuger E. Diversity and Abundance of Microbial Communities in UASB Reactors during Methane Production from Hydrolyzed Wheat Straw and Lucerne. Microorganisms 2020; 8:E1394. [PMID: 32932830 PMCID: PMC7565072 DOI: 10.3390/microorganisms8091394] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2020] [Revised: 09/04/2020] [Accepted: 09/09/2020] [Indexed: 01/04/2023] Open
Abstract
The use of straw for biofuel production is encouraged by the European Union. A previous study showed the feasibility of producing biomethane in upflow anaerobic sludge blanket (UASB) reactors using hydrolyzed, steam-pretreated wheat straw, before and after dark fermentation with Caldicellulosiruptor saccharolyticus, and lucerne. This study provides information on overall microbial community development in those UASB processes and changes related to acidification. The bacterial and archaeal community in granular samples was analyzed using high-throughput amplicon sequencing. Anaerobic digestion model no. 1 (ADM1) was used to predict the abundance of microbial functional groups. The sequencing results showed decreased richness and diversity in the microbial community, and decreased relative abundance of bacteria in relation to archaea, after process acidification. Canonical correspondence analysis showed significant negative correlations between the concentration of organic acids and three phyla, and positive correlations with seven phyla. Organic loading rate and total COD fed also showed significant correlations with microbial community structure, which changed over time. ADM1 predicted a decrease in acetate degraders after a decrease to pH ≤ 6.5. Acidification had a sustained effect on the microbial community and process performance.
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Affiliation(s)
- Tong Liu
- Department of Molecular Science, Swedish University of Agricultural Science, Uppsala BioCenter, 750 07 Uppsala, Sweden;
| | - Anna Schnürer
- Department of Molecular Science, Swedish University of Agricultural Science, Uppsala BioCenter, 750 07 Uppsala, Sweden;
| | - Johanna Björkmalm
- RISE, Forskningsbyn Ideon Scheelevägen 27, 223 70 Lund, Sweden; (J.B.); (K.W.)
| | - Karin Willquist
- RISE, Forskningsbyn Ideon Scheelevägen 27, 223 70 Lund, Sweden; (J.B.); (K.W.)
| | - Emma Kreuger
- Division of Biotechnology, Department of Chemistry, Lund University, P.O. Box 118, 221 00 Lund, Sweden
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8
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Lu D, Xing B, Liu Y, Wang Z, Xu X, Zhu L. Enhanced production of short-chain fatty acids from waste activated sludge by addition of magnetite under suitable alkaline condition. BIORESOURCE TECHNOLOGY 2019; 289:121713. [PMID: 31276993 DOI: 10.1016/j.biortech.2019.121713] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/06/2019] [Revised: 06/24/2019] [Accepted: 06/26/2019] [Indexed: 06/09/2023]
Abstract
Alkaline fermentation technology is an effective method for resource recovery, e.g., short-chain fatty acids (SCFAs), but the acidification process needs to be further enhanced. To improve the release and acidification of organic matters in waste activated sludge (WAS) fermentation simultaneously, a novel method was proposed with magnetite addition under alkaline condition in this study. Compared with the control, SCFAs and acetic acids yields increased by 21.2% ± 3.1% and 31.0% ± 1.2% in the 0.6 g/gVSS magnetite-based system, respectively. Besides, the activities of α-glucosidase, protease and acetate kinase (AK) were enhanced with magnetite addition, and the abundance of acidogenic microbes was improved obviously. Furthermore, magnetite reduced the release of PO43--P significantly via the precipitation reaction. Of all, a novel side-stream WAS hydrolysis and acidification process based on magnetite addition under suitable alkaline condition is proposed, realizing the efficient recovery of carbon and phosphorus resources along with wastewater and WAS treatment.
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Affiliation(s)
- Donghui Lu
- Institute of Environment Pollution Control and Treatment, Zhejiang University, Hangzhou 310058, China
| | - Bo Xing
- Shaoxing Environmental Monitoring Center, Shaoxing 312000, China
| | - Yuhan Liu
- Zhejiang University, Hangzhou 310058, China
| | - Zhirong Wang
- Zhejiang Provincal Office of Agricultural Ecology and Energy, Hangzhou 310012, China
| | - Xiangyang Xu
- Institute of Environment Pollution Control and Treatment, Zhejiang University, Hangzhou 310058, China; Zhejiang Province Key Laboratory for Water Pollution Control and Environmental Safety, Hangzhou 310058, China; Zhejiang Provincial Engineering Laboratory of Water Pollution Control, 388 Yuhangtang Road, Hangzhou 310058, China
| | - Liang Zhu
- Institute of Environment Pollution Control and Treatment, Zhejiang University, Hangzhou 310058, China; Zhejiang Province Key Laboratory for Water Pollution Control and Environmental Safety, Hangzhou 310058, China; Zhejiang Provincial Engineering Laboratory of Water Pollution Control, 388 Yuhangtang Road, Hangzhou 310058, China.
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9
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Luo L, Kaur G, Wong JWC. A mini-review on the metabolic pathways of food waste two-phase anaerobic digestion system. WASTE MANAGEMENT & RESEARCH : THE JOURNAL OF THE INTERNATIONAL SOLID WASTES AND PUBLIC CLEANSING ASSOCIATION, ISWA 2019; 37:333-346. [PMID: 30696377 DOI: 10.1177/0734242x18819954] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Food waste (FW) disposal has become a global social, environmental, and economic problem. The current practice of landfilling is undesirable due to its potential emission of greenhouse gas, nutrient recycling, and pollution of water resources. Anaerobic digestion (AD), particularly two-phase AD is a promising option to manage FW and recover energy in the form of methane and obtain value-added by-products. However, most current review literature focuses on operating conditions while often placing little emphasis on improving conversion efficiency through regulating intermediate products. The AD process involves complex metabolic reactions carried out by several microbial groups. Therefore, understanding of these metabolic pathways existing in AD is the key to design effective strategies for enrichment of specific microbial groups which can produce desired intermediates for methane production, which can possibly be achieved by an understanding of the influence of critical process parameters on these metabolic pathways. Thus, it is the aim of this review to describe the effect of process conditions on underlying metabolic pathways in order to allow an efficient manipulation of these pathways for enhancing methane production.
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Affiliation(s)
- Liwen Luo
- Sino-Forest Applied Research Centre for Pearl River Delta Environment and Department of Biology, Hong Kong Baptist University, Hong Kong SAR, Hong Kong
| | - Guneet Kaur
- Sino-Forest Applied Research Centre for Pearl River Delta Environment and Department of Biology, Hong Kong Baptist University, Hong Kong SAR, Hong Kong
| | - Jonathan W C Wong
- Sino-Forest Applied Research Centre for Pearl River Delta Environment and Department of Biology, Hong Kong Baptist University, Hong Kong SAR, Hong Kong
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10
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Temperature control as key factor for optimal biohydrogen production from thermomechanical pulping wastewater. Biochem Eng J 2018. [DOI: 10.1016/j.bej.2018.05.027] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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11
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Influence of support materials on continuous hydrogen production in anaerobic packed-bed reactor with immobilized hydrogen producing bacteria at acidic conditions. Enzyme Microb Technol 2018; 111:87-96. [DOI: 10.1016/j.enzmictec.2017.10.008] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2017] [Revised: 10/19/2017] [Accepted: 10/20/2017] [Indexed: 11/23/2022]
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12
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Yang GC, Zhou L, Mbadinga SM, You J, Yang HZ, Liu JF, Yang SZ, Gu JD, Mu BZ. Activation of CO2-reducing methanogens in oil reservoir after addition of nutrient. J Biosci Bioeng 2016; 122:740-747. [DOI: 10.1016/j.jbiosc.2016.06.011] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2016] [Revised: 05/29/2016] [Accepted: 06/19/2016] [Indexed: 10/21/2022]
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13
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Wan J, Jing Y, Zhang S, Angelidaki I, Luo G. Mesophilic and thermophilic alkaline fermentation of waste activated sludge for hydrogen production: Focusing on homoacetogenesis. WATER RESEARCH 2016; 102:524-532. [PMID: 27420808 DOI: 10.1016/j.watres.2016.07.002] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/27/2016] [Revised: 06/06/2016] [Accepted: 07/02/2016] [Indexed: 05/25/2023]
Abstract
The present study compared the mesophilic and thermophilic alkaline fermentation of waste activated sludge (WAS) for hydrogen production with focus on homoacetogenesis, which mediated the consumption of H2 and CO2 for acetate production. Batch experiments showed that hydrogen yield of WAS increased from 19.2 mL H2/gVSS at 37 °C and pH 10-80.1 mL H2/gVSS at 55 °C and pH 10. However, the production of volatile fatty acids (mainly acetate) was higher at 37 °C and pH 10 by comparison with 55 °C and pH 10. Hydrogen consumption due to homoacetogenesis was observed at 37 °C and pH 10 but not 55 °C and pH 10. Higher expression levels of genes relating with homoacetogenesis and lower expression levels of genes relating with hydrogen production were found at 37 °C and pH 10 compared to 55 °C and pH 10. The continuous experiment demonstrated the steady-state hydrogen yield of WAS was comparable to that obtained from batch experiments at 55 °C and pH 10, and homoacetogenesis was still inhibited. However, the steady-state hydrogen yield of WAS (6.5 mL H2/gVSS) was much lower than that (19.2 mL H2/gVSS) obtained from batch experiments at 37 °C and pH 10 due to the gradual enrichment of homoacetogens as demonstrated by qPCR analysis. The high-throughput sequencing analysis of 16S rRNA genes showed that the abundance of genus Clostridium, containing several homoacetogens, was 5 times higher at 37 °C and pH 10 than 55 °C and pH 10.
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Affiliation(s)
- Jingjing Wan
- Shanghai Key Laboratory of Atmospheric Particle Pollution and Prevention (LAP(3)), Department of Environmental Science and Engineering, Fudan University, 200433, Shanghai, China
| | - Yuhang Jing
- Shanghai Key Laboratory of Atmospheric Particle Pollution and Prevention (LAP(3)), Department of Environmental Science and Engineering, Fudan University, 200433, Shanghai, China
| | - Shicheng Zhang
- Shanghai Key Laboratory of Atmospheric Particle Pollution and Prevention (LAP(3)), Department of Environmental Science and Engineering, Fudan University, 200433, Shanghai, China
| | - Irini Angelidaki
- Department of Environmental Engineering, Technical University of Denmark, DK-2800, Kgs Lyngby, Denmark
| | - Gang Luo
- Shanghai Key Laboratory of Atmospheric Particle Pollution and Prevention (LAP(3)), Department of Environmental Science and Engineering, Fudan University, 200433, Shanghai, China.
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14
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Jin B, Wang S, Xing L, Li B, Peng Y. Long term effect of alkali types on waste activated sludge hydrolytic acidification and microbial community at low temperature. BIORESOURCE TECHNOLOGY 2016; 200:587-597. [PMID: 26546788 DOI: 10.1016/j.biortech.2015.10.036] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/19/2015] [Revised: 10/11/2015] [Accepted: 10/13/2015] [Indexed: 06/05/2023]
Abstract
The effect of four alkali reagents (NaOH, KOH, Ca(OH)2, mixed alkali) on waste activated sludge (WAS) hydrolytic acidification and microbial community was studied in semi-continuous fermentation systems at low temperature (15°C) over long term operational time (65day). The results showed that protein and polysaccharide of NaOH (124.26, 11.92) was similar to that of KOH (109.53, 11.30), both were higher than Ca(OH)2 (70.66, 3.74) and mixed alkali (90.66, 8.71). The short chain fatty acids (SCFAs) of NaOH (231.62) was higher than KOH (220.62mg chemical oxygen demand (COD)/g VSS). Although Ca(OH)2 system had strong acidification capacity, the shortage of SCFAs occurred due to the low activity of hydrolase. Illumina MiSeq sequencing revealed that Tissierella and Erysipelothrix were enriched in the NaOH and Ca(OH)2 systems, where Peptostreptococcaceae incertae_sedis was enriched in the NaOH and KOH systems, less Anaerolinea was involved in Ca(OH)2 condition.
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Affiliation(s)
- Baodan Jin
- Key Laboratory of Beijing for Water Quality Science and Water Environment Recovery Engineering, Engineering Research Center of Beijing, Beijing University of Technology, Beijing 100124, PR China
| | - Shuying Wang
- Key Laboratory of Beijing for Water Quality Science and Water Environment Recovery Engineering, Engineering Research Center of Beijing, Beijing University of Technology, Beijing 100124, PR China.
| | - Liqun Xing
- Key Laboratory of Beijing for Water Quality Science and Water Environment Recovery Engineering, Engineering Research Center of Beijing, Beijing University of Technology, Beijing 100124, PR China
| | - Baikun Li
- Key Laboratory of Beijing for Water Quality Science and Water Environment Recovery Engineering, Engineering Research Center of Beijing, Beijing University of Technology, Beijing 100124, PR China; Department of Civil and Environmental Engineering, University of Connecticut, Storrs, CT 06269, USA
| | - Yongzhen Peng
- Key Laboratory of Beijing for Water Quality Science and Water Environment Recovery Engineering, Engineering Research Center of Beijing, Beijing University of Technology, Beijing 100124, PR China
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15
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Müller B, Sun L, Westerholm M, Schnürer A. Bacterial community composition and fhs profiles of low- and high-ammonia biogas digesters reveal novel syntrophic acetate-oxidising bacteria. BIOTECHNOLOGY FOR BIOFUELS 2016; 9:48. [PMID: 26925165 PMCID: PMC4769498 DOI: 10.1186/s13068-016-0454-9] [Citation(s) in RCA: 99] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/08/2015] [Accepted: 02/08/2016] [Indexed: 05/04/2023]
Abstract
BACKGROUND Syntrophic acetate oxidation (SAO) is the predominant pathway for methane production in high ammonia anaerobic digestion processes. The bacteria (SAOB) occupying this niche and the metabolic pathway are poorly understood. Phylogenetic diversity and strict cultivation requirements hinder comprehensive research and discovery of novel SAOB. Most SAOB characterised to date are affiliated to the physiological group of acetogens. Formyltetrahydrofolate synthetase is a key enzyme of both acetogenic and SAO metabolism. The encoding fhs gene has therefore been identified as a suitable functional marker, using a newly designed primer pair. In this comparative study, we used a combination of terminal restriction fragment length polymorphism profiling, clone-based comparison, qPCR and Illumina amplicon sequencing to assess the bacterial community and acetogenic sub-community prevailing in high- and low-ammonia laboratory-scale digesters in order to delineate potential SAOB communities. Potential candidates identified were further tracked in a number of low-ammonia and high-ammonia laboratory-scale and large-scale digesters in order to reveal a potential function in SAO. RESULTS All methodical approaches revealed significant changes in the bacterial community composition concurrently with increasing ammonia and predominance of SAO. The acetogenic community under high ammonia conditions was revealed to be generally heterogeneous, but formed distinct phylogenetic clusters. The clusters differed clearly from those found under low-ammonia conditions and represented an acetogenic assemblage unique for biogas processes and recurring in a number of high-ammonia processes, indicating potential involvement in SAO. CONCLUSIONS The phylogenetic affiliation and population dynamics observed point to a key community, belonging mainly to the Clostridia class, in particular to the orders Clostridiales and Thermoanaerobacterales, which appear to specialise in SAO rather than being metabolically versatile. Overall, the results reported here provide evidence of functional importance of the bacterial families identified in high-ammonia systems and extend existing knowledge of bacterial and acetogenic assemblages at low and high ammonia levels. This information will be of help in monitoring and assessing the impacts on the SAOB community in order to identify characteristics of robust and productive high ammonia biogas processes.
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Affiliation(s)
- Bettina Müller
- Department of Microbiology, Uppsala BioCenter, Swedish University of Agricultural Sciences, Box 7025, 750 07 Uppsala, Sweden
| | - Li Sun
- Department of Microbiology, Uppsala BioCenter, Swedish University of Agricultural Sciences, Box 7025, 750 07 Uppsala, Sweden
| | - Maria Westerholm
- Department of Microbiology, Uppsala BioCenter, Swedish University of Agricultural Sciences, Box 7025, 750 07 Uppsala, Sweden
| | - Anna Schnürer
- Department of Microbiology, Uppsala BioCenter, Swedish University of Agricultural Sciences, Box 7025, 750 07 Uppsala, Sweden
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16
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Xu S, Fu B, Zhang L, Liu H. Bioconversion of H2/CO 2 by acetogen enriched cultures for acetate and ethanol production: the impact of pH. World J Microbiol Biotechnol 2015; 31:941-50. [PMID: 25838196 DOI: 10.1007/s11274-015-1848-8] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2014] [Accepted: 03/11/2015] [Indexed: 12/29/2022]
Abstract
Syngas fermentation into ethanol and other bioproducts by mixed cultures is considered a promising biotechnology. Effects of pH on product generation and microbial community during H2/CO2 utilization by acetogen enrichment cultures were investigated in this work. The maximum acetate concentration reached 95.41 mmol L(-1) at pH 7, which was 71.7, 21.8 and 50.9% higher than at pH 5, 9 and 11, respectively. The maximum ethanol concentration at pH 7 was 45.7, 50, 72% higher than that at pH 5, 9 and 11, respectively. The CO dehydrogenase (CODH) gene copy number was highest at pH 7, indicating that metabolically active acetogens reached their highest level at pH 7. The CODH gene copy number at pH 9 was lower than at pH 7, but higher than at pH 5 and 11. Correspondingly, the enrichment cultures at pH 7 had the highest species richness and diversity, while those at pH 9 had the second highest diversity, and those at pH 5 and 11 had the lowest diversity. The shift in microbial community structure and the different active acetogen contents resulting from different pHs were responsible for the differences in acetate and ethanol production.
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Affiliation(s)
- Shuyun Xu
- Laboratory of Environmental Biotechnology, School of Environmental and Civil Engineering, Jiangnan University, Wuxi, 214122, Jiangsu Province, China
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17
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Liu JF, Sun XB, Yang GC, Mbadinga SM, Gu JD, Mu BZ. Analysis of microbial communities in the oil reservoir subjected to CO2-flooding by using functional genes as molecular biomarkers for microbial CO2 sequestration. Front Microbiol 2015; 6:236. [PMID: 25873911 PMCID: PMC4379918 DOI: 10.3389/fmicb.2015.00236] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/25/2014] [Accepted: 03/10/2015] [Indexed: 11/13/2022] Open
Abstract
Sequestration of CO2 in oil reservoirs is considered to be one of the feasible options for mitigating atmospheric CO2 building up and also for the in situ potential bioconversion of stored CO2 to methane. However, the information on these functional microbial communities and the impact of CO2 storage on them is hardly available. In this paper a comprehensive molecular survey was performed on microbial communities in production water samples from oil reservoirs experienced CO2-flooding by analysis of functional genes involved in the process, including cbbM, cbbL, fthfs, [FeFe]-hydrogenase, and mcrA. As a comparison, these functional genes in the production water samples from oil reservoir only experienced water-flooding in areas of the same oil bearing bed were also analyzed. It showed that these functional genes were all of rich diversity in these samples, and the functional microbial communities and their diversity were strongly affected by a long-term exposure to injected CO2. More interestingly, microorganisms affiliated with members of the genera Methanothemobacter, Acetobacterium, and Halothiobacillus as well as hydrogen producers in CO2 injected area either increased or remained unchanged in relative abundance compared to that in water-flooded area, which implied that these microorganisms could adapt to CO2 injection and, if so, demonstrated the potential for microbial fixation and conversion of CO2 into methane in subsurface oil reservoirs.
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Affiliation(s)
- Jin-Feng Liu
- State Key Laboratory of Bioreactor Engineering and Institute of Applied Chemistry, East China University of Science and Technology Shanghai, China
| | - Xiao-Bo Sun
- State Key Laboratory of Bioreactor Engineering and Institute of Applied Chemistry, East China University of Science and Technology Shanghai, China
| | - Guang-Chao Yang
- State Key Laboratory of Bioreactor Engineering and Institute of Applied Chemistry, East China University of Science and Technology Shanghai, China
| | - Serge M Mbadinga
- State Key Laboratory of Bioreactor Engineering and Institute of Applied Chemistry, East China University of Science and Technology Shanghai, China
| | - Ji-Dong Gu
- School of Biological Sciences, University of Hong Kong Hong Kong, China
| | - Bo-Zhong Mu
- State Key Laboratory of Bioreactor Engineering and Institute of Applied Chemistry, East China University of Science and Technology Shanghai, China
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18
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Fe0 enhanced acetification of propionate and granulation of sludge in acidogenic reactor. Appl Microbiol Biotechnol 2015; 99:6083-9. [DOI: 10.1007/s00253-015-6449-9] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2014] [Revised: 01/27/2015] [Accepted: 01/28/2015] [Indexed: 10/23/2022]
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19
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Hao J, Wang H. Volatile fatty acids productions by mesophilic and thermophilic sludge fermentation: Biological responses to fermentation temperature. BIORESOURCE TECHNOLOGY 2015; 175:367-73. [PMID: 25459844 DOI: 10.1016/j.biortech.2014.10.106] [Citation(s) in RCA: 96] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/27/2014] [Revised: 10/19/2014] [Accepted: 10/20/2014] [Indexed: 05/04/2023]
Abstract
The volatile fatty acids (VFAs) productions, as well as hydrolases activities, microbial communities, and homoacetogens, of mesophilic and thermophilic sludge anaerobic fermentation were investigated to reveal the microbial responses to different fermentation temperatures. Thermophilic fermentation led to 10-fold more accumulation of VFAs compared to mesophilic fermentation. α-glucosidase and protease had much higher activities in thermophilic reactor, especially protease. Illumina sequencing manifested that raising fermentation temperature increased the abundances of Clostridiaceae, Microthrixaceae and Thermotogaceae, which could facilitate either hydrolysis or acidification. Real-time PCR analysis demonstrated that under thermophilic condition the relative abundance of homoacetogens increased in batch tests and reached higher level at stable fermentation, whereas under mesophilic condition it only increased slightly in batch tests. Therefore, higher fermentation temperature increased the activities of key hydrolases, raised the proportions of bacteria involved in hydrolysis and acidification, and promoted the relative abundance of homoacetogens, which all resulted in higher VFAs production.
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Affiliation(s)
- Jiuxiao Hao
- State Key Joint Laboratory of Environment Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing 100084, China
| | - Hui Wang
- State Key Joint Laboratory of Environment Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing 100084, China.
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20
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Bengelsdorf FR, Straub M, Dürre P. Bacterial synthesis gas (syngas) fermentation. ENVIRONMENTAL TECHNOLOGY 2013; 34:1639-51. [PMID: 24350425 DOI: 10.1080/09593330.2013.827747] [Citation(s) in RCA: 118] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
Acetogenic bacteria employing the Wood-Ljungdahl pathway can be used as biocatalysts in syngas fermentation for the production ofbiofuels such as ethanol or butanol as well as biocommodities such as acetate, lactate, butyrate, 2,3 butanediol, and acetone. The potential of such processes can be projected by the global syngas output, which was 70,817 megawatts thermal in 2010 and is expected to increase up to 72% in 2016. To date, different acetogens are used as commercial production strains for industrial syngas fermentations in pilot or demonstration plants (Coskata, INEOS Bio, LanzaTech) and first commercial units are expected to launch operation in the near future (INEOS Bio, LanzaTech). Considerations on potential yields are quite promising for fermentative production. New methods for metabolic engineering were established to construct novel recombinant acetogenic biocatalysts. Synthetic biology will certainly play a major role in constructing strains for commercial operations. This way, a cheap and abundant carbon source most probably replace, processes based on crude oil or sugar in the near future.
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Affiliation(s)
- Frank R Bengelsdorf
- Institute of Microbiology and Biotechnology, University of Ulm, Albert-Einstein-Allee 11, Ulm D-89081, Germany.
| | - Melanie Straub
- Institute of Microbiology and Biotechnology, University of Ulm, Albert-Einstein-Allee 11, Ulm D-89081, Germany
| | - Peter Dürre
- Institute of Microbiology and Biotechnology, University of Ulm, Albert-Einstein-Allee 11, Ulm D-89081, Germany
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21
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Westerholm M, Müller B, Arthurson V, Schnürer A. Changes in the acetogenic population in a mesophilic anaerobic digester in response to increasing ammonia concentration. Microbes Environ 2011; 26:347-53. [PMID: 21869569 DOI: 10.1264/jsme2.me11123] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Changes in the acetogenic population were investigated in an experimental laboratory-scale biogas reactor (37°C) subjected to gradually elevated ammonia levels (0.8 to 6.9 g NH(4)(+)-N L(-1)). A shift from aceticlastic acetate degradation to syntrophic acetate oxidation had previously been confirmed in this reactor. In a parallel control reactor, operating at constant ammonia levels (0.65-0.90 g NH(4)(+)-N L(-1)), acetate degradation proceeded via the aceticlastic pathway throughout the operating period (660 d). The acetogenic populations in the reactors were analysed using degenerated primers designed to target the functional gene encoding a key enzyme of the acetyl-CoA pathway, 10-formyltetrahydrofolate synthetase (FTHFS). The analysis consisted of terminal restriction fragment length polymorphism (T-RFLP) analysis coupled with the construction of clone libraries, and quantitative PCR (qPCR) analysis. The T-RFLP data obtained were statistically analysed by non-metric multidimensional scaling. The most abundant FTHFS genes recovered in the clone libraries were assigned to terminal restriction fragments of the T-RFLP profile. The results of the investigation clearly indicated that increased ammonia concentration substantially influenced the putative acetogenic population structure and caused two distinct shifts of the most abundant members; however, the identity of the dominating species remains unknown, as none of the genes had been identified previously. Despite the shifts in the population, the qPCR analysis revealed a relatively stable abundance of the acetogenic population throughout the operation.
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Affiliation(s)
- Maria Westerholm
- Department of Microbiology, Uppsala BioCenter, Swedish University of Agricultural Sciences, Uppsala, Sweden
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22
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Presence of novel, potentially homoacetogenic bacteria in the rumen as determined by analysis of formyltetrahydrofolate synthetase sequences from ruminants. Appl Environ Microbiol 2010; 76:2058-66. [PMID: 20118378 DOI: 10.1128/aem.02580-09] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Homoacetogens produce acetate from H(2) and CO(2) via the Wood-Ljungdahl pathway. Some homoacetogens have been isolated from the rumen, but these organisms are expected to be only part of the full diversity present. To survey the presence of rumen homoacetogens, we analyzed sequences of formyltetrahydrofolate synthetase (FTHFS), a key enzyme of the Wood-Ljungdahl pathway. A total of 275 partial sequences of genes encoding FTHFS were PCR amplified from rumen contents of a cow, two sheep, and a deer. Phylogenetic trees were constructed using these FTHFS gene sequences and the translated amino acid sequences, together with other sequences from public databases and from novel nonhomoacetogenic bacteria isolated from the rumen. Over 90% of the FTHFS sequences fell into 34 clusters defined with good bootstrap support. Few rumen-derived FTHFS sequences clustered with sequences of known homoacetogens. Conserved residues were identified in the deduced FTHFS amino acid sequences from known homoacetogens, and their presence in the other sequences was used to determine a "homoacetogen similarity" (HS) score. A homoacetogen FTHFS profile hidden Markov model (HoF-HMM) was used to assess the homology of rumen and homoacetogen FTHFS sequences. Many clusters had low HS scores and HoF-HMM matches, raising doubts about whether the sequences originated from homoacetogens. In keeping with these findings, FTHFS sequences from nonhomoacetogenic bacterial isolates grouped in these clusters with low scores. However, sequences that formed 10 clusters containing no known isolates but representing 15% of our FTHFS sequences from rumen samples had high HS scores and HoF-HMM matches and so could represent novel homoacetogens.
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