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Wu L, Ngo HH, Wang C, Hou Y, Chen X, Guo W, Duan H, Ni BJ, Wei W. Lactobacillus inoculation mediated carboxylates and alcohols production from waste activated sludge fermentation system: Insight into process outcomes and metabolic network. BIORESOURCE TECHNOLOGY 2024; 409:131191. [PMID: 39094964 DOI: 10.1016/j.biortech.2024.131191] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/23/2024] [Revised: 07/28/2024] [Accepted: 07/30/2024] [Indexed: 08/04/2024]
Abstract
Producing medium chain fatty acids (MCFAs) from waste activated sludge (WAS) is crucial for sustainable chemical industries. This study addressed the electron donor requirement for MCFAs production by inoculating Lactobacillus at varying concentrations (7.94 × 1010, 3.18 × 1011, and 6.35 × 1011 cell/L) to supply lactate internally. Interestingly, the highest MCFAs yield (∼2000 mg COD/L) occurred at the lowest Lactobacillus inoculation. Higher inoculation concentrations redirected more carbon from WAS towards alcohols production rather than MCFAs generation, with up to 2852 mg COD/L alcohols obtained under 6.35 × 1011 cell/L inoculation. Clostridium dominance and increased genes abundance for substrate hydrolysis, lactate conversion, and MCFAs/alcohol production collectively enhanced WAS-derived MCFAs and alcohols synthesis after Lactobacillus inoculation. Overall, the strategy of Lactobacillus inoculation regulated fermentation outcomes and subsequent carbon recovery in WAS, presenting a sustainable technology to achieve liquid bio-energy production from underutilized wet wastes.
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Affiliation(s)
- Lan Wu
- Centre for Technology in Water and Wastewater, School of Civil and Environmental Engineering, University of Technology Sydney, Sydney, NSW 2007, Australia
| | - Huu Hao Ngo
- Centre for Technology in Water and Wastewater, School of Civil and Environmental Engineering, University of Technology Sydney, Sydney, NSW 2007, Australia
| | - Chen Wang
- School of Civil and Environmental Engineering, The University of New South Wales, Sydney, NSW 2052, Australia
| | - Yanan Hou
- School of Civil and Environmental Engineering, The University of New South Wales, Sydney, NSW 2052, Australia
| | - Xueming Chen
- College of Environment and Safety Engineering, Fuzhou University, Fuzhou 350116, China
| | - Wenshan Guo
- Centre for Technology in Water and Wastewater, School of Civil and Environmental Engineering, University of Technology Sydney, Sydney, NSW 2007, Australia
| | - Haoran Duan
- School of Civil and Environmental Engineering, The University of New South Wales, Sydney, NSW 2052, Australia
| | - Bing-Jie Ni
- School of Civil and Environmental Engineering, The University of New South Wales, Sydney, NSW 2052, Australia
| | - Wei Wei
- Centre for Technology in Water and Wastewater, School of Civil and Environmental Engineering, University of Technology Sydney, Sydney, NSW 2007, Australia.
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2
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Wang Z, Chen J, Veiga MC, Kennes C. Bioconversion of pure CO 2 to caproic acid with zero valent iron: Optimizing carbon flux distribution in co-cultures of Acetobacterium woodii and Megasphaera hexanoica. BIORESOURCE TECHNOLOGY 2024; 413:131480. [PMID: 39265751 DOI: 10.1016/j.biortech.2024.131480] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/04/2024] [Revised: 08/28/2024] [Accepted: 09/09/2024] [Indexed: 09/14/2024]
Abstract
Acetobacterium woodii and Megasphaera hexanoica were co-cultured for caproic acid (CA) production from lactic acid (LA) and CO2. Also, various concentrations (1 g/L, 3 g/L, 5 g/L, and 10 g/L) of Zero Valent Iron (ZVI) were supplied to study its impact on the co-culture system. In flask experiments, 10 g/L LA and 1.0 bar CO2 produced 0.6 g/L CA with some biomass growth. ZVI increased LA consumption and CA production. Indeed, 3 g/L ZVI boosted CA production by 186 % and biomass accumulation by 103 %, suggesting that ZVI controls the carbon flux. Subsequent automated bioreactor studies showed that 3 g/L ZVI produced 1.842 g/L CA at stable pH, compared to 0.969 g/L without ZVI (control). Further, metabolic activity showed that both bacteria could directly use H2, generated by ZVI (3 g/L), as electron donor. Higher ZVI concentrations (10 g/L) resulted in Fe2+ causing excessive oxidation pressure on M. hexanoica, with its carbon flux flowing preferentially towards biomass. Enzyme assays confirmed that A. woodii preferred 10 g/L ZVI while M. hexanoica preferred 3 g/L for optimal bioconversion.
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Affiliation(s)
- Zeyu Wang
- Chemical Engineering Laboratory, Faculty of Sciences and Interdisciplinary Centre of Chemistry and Biology - Centro Interdisciplinar de Química y Biología (CICA), BIOENGIN Group, University of La Coruña (UDC), E-15008 La Coruña, Spain; Key Laboratory of Pollution Exposure and Health Intervention of Zhejiang Province, Interdisciplinary Research Academy, Zhejiang Shuren University, Hangzhou 310015, China
| | - Jun Chen
- Key Laboratory of Pollution Exposure and Health Intervention of Zhejiang Province, Interdisciplinary Research Academy, Zhejiang Shuren University, Hangzhou 310015, China
| | - María C Veiga
- Chemical Engineering Laboratory, Faculty of Sciences and Interdisciplinary Centre of Chemistry and Biology - Centro Interdisciplinar de Química y Biología (CICA), BIOENGIN Group, University of La Coruña (UDC), E-15008 La Coruña, Spain
| | - Christian Kennes
- Chemical Engineering Laboratory, Faculty of Sciences and Interdisciplinary Centre of Chemistry and Biology - Centro Interdisciplinar de Química y Biología (CICA), BIOENGIN Group, University of La Coruña (UDC), E-15008 La Coruña, Spain.
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3
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Bian B, Zhang W, Yu N, Yang W, Xu J, Logan BE, Saikaly PE. Lactate-mediated medium-chain fatty acid production from expired dairy and beverage waste. ENVIRONMENTAL SCIENCE AND ECOTECHNOLOGY 2024; 21:100424. [PMID: 38774191 PMCID: PMC11106833 DOI: 10.1016/j.ese.2024.100424] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/13/2023] [Revised: 04/18/2024] [Accepted: 04/18/2024] [Indexed: 05/24/2024]
Abstract
Fruits, vegetables, and dairy products are typically the primary sources of household food waste. Currently, anaerobic digestion is the most used bioprocess for the treatment of food waste with concomitant generation of biogas. However, to achieve a circular carbon economy, the organics in food waste should be converted to new chemicals with higher value than energy. Here we demonstrate the feasibility of medium-chain carboxylic acid (MCCA) production from expired dairy and beverage waste via a chain elongation platform mediated by lactate. In a two-stage fermentation process, the first stage with optimized operational conditions, including varying temperatures and organic loading rates, transformed expired dairy and beverage waste into lactate at a concentration higher than 900 mM C at 43 °C. This lactate was then used to produce >500 mM C caproate and >300 mM C butyrate via microbial chain elongation. Predominantly, lactate-producing microbes such as Lactobacillus and Lacticaseibacillus were regulated by temperature and could be highly enriched under mesophilic conditions in the first-stage reactor. In the second-stage chain elongation reactor, the dominating microbes were primarily from the genera Megasphaera and Caproiciproducens, shaped by varying feed and inoculum sources. Co-occurrence network analysis revealed positive correlations among species from the genera Caproiciproducens, Ruminococcus, and CAG-352, as well as Megasphaera, Bacteroides, and Solobacterium, indicating strong microbial interactions that enhance caproate production. These findings suggest that producing MCCAs from expired dairy and beverage waste via lactate-mediated chain elongation is a viable method for sustainable waste management and could serve as a chemical production platform in the context of building a circular bioeconomy.
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Affiliation(s)
- Bin Bian
- Water Desalination and Reuse Center (WDRC), King Abdullah University of Science and Technology (KAUST), Thuwal 23955-6900, Kingdom of Saudi Arabia
- Department of Civil and Environmental Engineering, The Pennsylvania State University, University Park, PA, 16802, USA
| | - Wenxiang Zhang
- Water Desalination and Reuse Center (WDRC), King Abdullah University of Science and Technology (KAUST), Thuwal 23955-6900, Kingdom of Saudi Arabia
- Research Centre of Ecology & Environment for Coastal Area and Deep Sea, Southern Marine Science and Engineering Guangdong Laboratory (Guangzhou), Guangzhou, 511458, China
| | - Najiaowa Yu
- Department of Civil and Environmental Engineering, The Pennsylvania State University, University Park, PA, 16802, USA
| | - Wei Yang
- Water Desalination and Reuse Center (WDRC), King Abdullah University of Science and Technology (KAUST), Thuwal 23955-6900, Kingdom of Saudi Arabia
| | - Jiajie Xu
- Water Desalination and Reuse Center (WDRC), King Abdullah University of Science and Technology (KAUST), Thuwal 23955-6900, Kingdom of Saudi Arabia
- School of Marine Science, Ningbo University, Ningbo, 315211, China
| | - Bruce E. Logan
- Department of Civil and Environmental Engineering, The Pennsylvania State University, University Park, PA, 16802, USA
| | - Pascal E. Saikaly
- Water Desalination and Reuse Center (WDRC), King Abdullah University of Science and Technology (KAUST), Thuwal 23955-6900, Kingdom of Saudi Arabia
- Environmental Science and Engineering Program, Biological and Environmental Science and Engineering (BESE) Division, King Abdullah University of Science and Technology (KAUST), Thuwal 23955-6900, Kingdom of Saudi Arabia
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Liu Y, Chen L, Duan Y, Li R, Yang Z, Liu S, Li G. Recent progress and prospects for chain elongation of transforming biomass waste into medium-chain fatty acids. CHEMOSPHERE 2024; 355:141823. [PMID: 38552798 DOI: 10.1016/j.chemosphere.2024.141823] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/04/2024] [Revised: 03/18/2024] [Accepted: 03/26/2024] [Indexed: 04/06/2024]
Abstract
Chain elongation technology utilises microorganisms in anaerobic digestion to transform waste biomass into medium-chain fatty acids that have greater economic value. This innovative technology expands upon traditional anaerobic digestion methods, requiring abundant substrates that serve as electron donors and acceptors, and inoculating microorganisms with chain elongation functions. While this process may result in the production of by-products and elicit competitive responses, toxicity suppression of microorganisms by substrates and products remains a significant obstacle to the industrialisation of chain elongation technology. This study provides a comprehensive overview of existing research on widely employed electron donors and their synthetic reactions, competitive reactions, inoculum selection, toxicity inhibition of substrates and products, and increased chain elongation approaches. Additionally, it presents actionable recommendations for future research and development endeavours in this domain, intending to inspire and guide researchers in advancing the frontiers of chain elongation technology.
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Affiliation(s)
- Yuhao Liu
- School of Environmental and Municipal Engineering, North China University of Water Resources and Electric Power, Zhengzhou, 450046, Henan Province, China.
| | - Long Chen
- School of Environmental and Municipal Engineering, North China University of Water Resources and Electric Power, Zhengzhou, 450046, Henan Province, China
| | - Yacong Duan
- School of Environmental and Municipal Engineering, North China University of Water Resources and Electric Power, Zhengzhou, 450046, Henan Province, China
| | - Ruihua Li
- School of Environmental and Municipal Engineering, North China University of Water Resources and Electric Power, Zhengzhou, 450046, Henan Province, China
| | - Ziyan Yang
- School of Environmental and Municipal Engineering, North China University of Water Resources and Electric Power, Zhengzhou, 450046, Henan Province, China
| | - Shuli Liu
- School of Environmental and Municipal Engineering, North China University of Water Resources and Electric Power, Zhengzhou, 450046, Henan Province, China
| | - Guoting Li
- School of Environmental and Municipal Engineering, North China University of Water Resources and Electric Power, Zhengzhou, 450046, Henan Province, China
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Deng M, Hu X, Zhang Y, Zhang X, Ni H, Fu D, Chi L. Illuminating the Characteristics and Assembly of Prokaryotic Communities across a pH Gradient in Pit Muds for the Production of Chinese Strong-Flavor Baijiu. Foods 2024; 13:1196. [PMID: 38672869 PMCID: PMC11048939 DOI: 10.3390/foods13081196] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2024] [Revised: 04/09/2024] [Accepted: 04/11/2024] [Indexed: 04/28/2024] Open
Abstract
Pit mud (PM), as an important source of microorganisms, is necessary for Chinese strong-flavor baijiu (CSFB) production. Although it has been revealed that the PM prokaryotic community diversities are influenced by its quality, product area, ages, etc., the characteristics and assembly process of the prokaryotic community in PMs across a pH gradient are still unclear. In this study, the regular changes of α- and β-diversities of the prokaryotic community across a pH gradient in PMs were revealed, which could be divided into "stable", "relatively stable", and "drastically changed" periods. A total of 27 phyla, 53 classes, and 381 genera were observed in all given samples, dominated by Firmicutes, Bacteroidetes, Proteobacteria, Lactobacillus, Caproiciproducens, Proteiniphilum, etc. Meanwhile, the complexity of the network structure of the prokaryotic microbial communities is significantly influenced by pH. The community assembly was jointly shaped by deterministic and stochastic processes, with stochastic process contributing more. This study was a specialized report on elucidating the characteristics and assembly of PM prokaryotic communities across a pH gradient, and revealed that the diversity and structure of PM prokaryotic communities could be predictable, to some degree, which could contribute to expanding our understanding of prokaryotic communities in PM.
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Affiliation(s)
- Mingdong Deng
- Food Laboratory of Zhongyuan, Henan Key Laboratory of Cold Chain Food Quality and Safety Control, College of Food and Bioengineering, Zhengzhou University of Light Industry, Zhengzhou 450001, China
| | - Xiaolong Hu
- Food Laboratory of Zhongyuan, Henan Key Laboratory of Cold Chain Food Quality and Safety Control, College of Food and Bioengineering, Zhengzhou University of Light Industry, Zhengzhou 450001, China
| | - Yong Zhang
- Food Laboratory of Zhongyuan, Henan Key Laboratory of Cold Chain Food Quality and Safety Control, College of Food and Bioengineering, Zhengzhou University of Light Industry, Zhengzhou 450001, China
| | - Xinyu Zhang
- School of Life Science and Technology, Xi’an Jiaotong University, Xi’an 710048, China
| | - Haifeng Ni
- Food Laboratory of Zhongyuan, Henan Key Laboratory of Cold Chain Food Quality and Safety Control, College of Food and Bioengineering, Zhengzhou University of Light Industry, Zhengzhou 450001, China
| | - Danyang Fu
- Food Laboratory of Zhongyuan, Henan Key Laboratory of Cold Chain Food Quality and Safety Control, College of Food and Bioengineering, Zhengzhou University of Light Industry, Zhengzhou 450001, China
| | - Lei Chi
- Food Laboratory of Zhongyuan, Henan Key Laboratory of Cold Chain Food Quality and Safety Control, College of Food and Bioengineering, Zhengzhou University of Light Industry, Zhengzhou 450001, China
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Wang Z, Fernández-Blanco C, Chen J, Veiga MC, Kennes C. Effect of electron acceptors on product selectivity and carbon flux in carbon chain elongation with Megasphaera hexanoica. THE SCIENCE OF THE TOTAL ENVIRONMENT 2024; 912:169509. [PMID: 38141983 DOI: 10.1016/j.scitotenv.2023.169509] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/06/2023] [Revised: 12/14/2023] [Accepted: 12/17/2023] [Indexed: 12/25/2023]
Abstract
Megasphaera hexanoica is a bacterial strain following the reverse β-oxidation pathway to synthesize caproate (CA) using lactate (LA) as an electron donor (ED) and acetate (AA) or butyrate (BA) as electron acceptors (EA). Differences in the type and concentration of EA lead to distinctions in product distribution and energy bifurcation of carbon fluxes in ED pathways, thereby affecting CA production. In this study, the effect of various ratios of AA, BA, and AA+BA as EA on carbon flux and CA specific titer during the carbon chain elongation in M. hexanoica was explored. The results indicated that the maximum levels of CA were 18.81 mM and 31.48 mM when the molar ratios of LA/AA and LA/BA were 10:1 and 3:1, respectively. Meanwhile, when AA and BA were used as combined EA (LA, AA, and BA molar amounts of 100, 23, and 77 mM), a maximum CA production of 39.45 mM was obtained. Further analysis revealed that the combined EA exhibited a CA production carbon flux of 49 % (4.3 % and 19.5 % higher compared to AA or BA, respectively) and a CA production specific titer of 45.24 mol (80.89 % and 58.51 % higher compared to AA or BA, respectively), indicating that the effective carbon utilization rate and CA production efficiency were greatly improved. Finally, a scaled-up experiment was conducted in a 1.2 L (working volume) automated bioreactor, implying high biomass (optical density at 600 nm or OD600 = 1.809) and a slight decrease in CA production (28.45 mM). A decrease in H2 production (4.11 g/m3) and an increase in CO2 production (0.632 g/m3) demonstrated the appropriate metabolic adaptation of M. hexanoica to environmental changes such as stirring shear.
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Affiliation(s)
- Zeyu Wang
- Chemical Engineering Laboratory, Faculty of Sciences and Interdisciplinary Centre of Chemistry and Biology - Centro Interdisciplinar de Química y Biología (CICA), BIOENGIN group, University of La Coruña (UDC), E-15008 La Coruña, Spain; Key Laboratory of Pollution Exposure and Health Intervention of Zhejiang Province, Interdisciplinary Research Academy, Zhejiang Shuren University, Hangzhou 310015, China
| | - Carla Fernández-Blanco
- Chemical Engineering Laboratory, Faculty of Sciences and Interdisciplinary Centre of Chemistry and Biology - Centro Interdisciplinar de Química y Biología (CICA), BIOENGIN group, University of La Coruña (UDC), E-15008 La Coruña, Spain
| | - Jun Chen
- Key Laboratory of Pollution Exposure and Health Intervention of Zhejiang Province, Interdisciplinary Research Academy, Zhejiang Shuren University, Hangzhou 310015, China
| | - María C Veiga
- Chemical Engineering Laboratory, Faculty of Sciences and Interdisciplinary Centre of Chemistry and Biology - Centro Interdisciplinar de Química y Biología (CICA), BIOENGIN group, University of La Coruña (UDC), E-15008 La Coruña, Spain
| | - Christian Kennes
- Chemical Engineering Laboratory, Faculty of Sciences and Interdisciplinary Centre of Chemistry and Biology - Centro Interdisciplinar de Química y Biología (CICA), BIOENGIN group, University of La Coruña (UDC), E-15008 La Coruña, Spain.
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7
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Wu SL, Long Y, Wei W, Shi X, Shen D, Ni BJ. Co-electron donors driven medium-chain fatty acids production: Roles of electron donors, reaction kinetics and metabolic pathways. CHEMOSPHERE 2023; 338:139515. [PMID: 37474034 DOI: 10.1016/j.chemosphere.2023.139515] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/14/2023] [Revised: 07/07/2023] [Accepted: 07/14/2023] [Indexed: 07/22/2023]
Abstract
Energy conversion of waste activated sludge alkaline fermentation liquor (WASAFL) to medium-chain fatty acids (MCFAs) is promising for sludge treatment and carbon recovery. However, the single electron donor (ED) fermentation for MCFAs production has irreparable defects. To resolve the respective shortcomings of single electron donor (ED) and improve the MCFAs production efficiency from WASAFL, a novel biotechnical process utilizing ethanol and lactate as co-EDs within different combination ratios were investigated. The results verified that MCFAs production was highest with ethanol to lactate ratio of 1:3 (6988.54 ± 208.18 mg COD/L), being 1.46 and 1.87 times of that with ethanol and lactate as single ED. The kinetic analysis results confirmed that ethanol to lactate ratio of 1:3 resulted in the highest MCFAs yield and formation rate. The microbial taxa results uncovered that the relative abundance of Sphaerochaeta and Haloimpatiens showed positive correlation with MCFAs production. The metabolic pathway analysis indicated that the ethanol oxidization, lactate oxidization, acrylate pathway, reverse β oxidization and fatty acid biosynthesis pathway might take place in the WASAFL fermentation system, contributing to the WASAFL-to-MCFAs conversion.
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Affiliation(s)
- Shu-Lin Wu
- Zhejiang Provincial Key Laboratory of Solid Waste Treatment and Recycling, Zhejiang Engineering Research Center of Non-ferrous Metal Waste Recycling, Zhejiang Gongshang University, China
| | - Yuyang Long
- Zhejiang Provincial Key Laboratory of Solid Waste Treatment and Recycling, Zhejiang Engineering Research Center of Non-ferrous Metal Waste Recycling, Zhejiang Gongshang University, China
| | - Wei Wei
- Centre for Technology in Water and Wastewater, School of Civil and Environmental Engineering, University of Technology Sydney, Sydney, NSW, 2007, Australia
| | - Xingdong Shi
- Centre for Technology in Water and Wastewater, School of Civil and Environmental Engineering, University of Technology Sydney, Sydney, NSW, 2007, Australia
| | - Dongsheng Shen
- Zhejiang Provincial Key Laboratory of Solid Waste Treatment and Recycling, Zhejiang Engineering Research Center of Non-ferrous Metal Waste Recycling, Zhejiang Gongshang University, China
| | - Bing-Jie Ni
- Centre for Technology in Water and Wastewater, School of Civil and Environmental Engineering, University of Technology Sydney, Sydney, NSW, 2007, Australia.
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Li L, Liu C, Xu L, Zhuang H, He J, He Q, Zhang J. Acclimation of anaerobic fermentation microbiome with acetate and ethanol for chain elongation and the biochemical response. CHEMOSPHERE 2023; 320:138083. [PMID: 36754309 DOI: 10.1016/j.chemosphere.2023.138083] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/07/2022] [Revised: 01/10/2023] [Accepted: 02/05/2023] [Indexed: 06/18/2023]
Abstract
Medium chain fatty acids (MCFAs) production is a promising method for resource recovery from organic wastes. In this study, the microbial community structure shift along the long-term acclimation experiment and the concomitant effect of H2 level on chain elongation performance was investigated. Chain elongation microbiome could be rapidly acclimated from traditional anaerobic fermentation consortia. Genera Caproiciproducens, Clostridium sensu stricto 12, Rummeliibacillus and Oscillibacter was found to be dominant during the operation. The H2 was accumulated in the headspace by increasing the ethanol input, which inhibited oxidation of caproate and butyrate immediately, while its inhibition effect on chain elongation was delayed. H2 level in the headspace was positively correlated to the MCFAs production related bacteria. However, too much H2 accumulated might be suppressive for MCFAs production in the long term. It might result from the thermodynamic barrier for discarding excess reducing equivalents under high H2 level, which further gave rise to ethanol accumulation in this system.
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Affiliation(s)
- Lin Li
- College of Environment and Ecology, Chongqing University, Chongqing 400044, China; State Key Laboratory of Urban Water Resource and Environment, School of Environment, Harbin Institute of Technology, Harbin 150090, China
| | - Chang Liu
- College of Environment and Ecology, Chongqing University, Chongqing 400044, China
| | - Linji Xu
- College of Environment and Ecology, Chongqing University, Chongqing 400044, China.
| | - Huichuan Zhuang
- Department of Civil and Environmental Engineering, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong
| | - Junguo He
- State Key Laboratory of Urban Water Resource and Environment, School of Environment, Harbin Institute of Technology, Harbin 150090, China; School of Civil Engineering, Guangzhou University, Guangzhou 510006, China.
| | - Qiang He
- College of Environment and Ecology, Chongqing University, Chongqing 400044, China
| | - Jie Zhang
- State Key Laboratory of Urban Water Resource and Environment, School of Environment, Harbin Institute of Technology, Harbin 150090, China
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9
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Crognale S, Massimi A, Sbicego M, Braguglia CM, Gallipoli A, Gazzola G, Gianico A, Tonanzi B, Di Pippo F, Rossetti S. Ecology of food waste chain-elongating microbiome. Front Bioeng Biotechnol 2023; 11:1157243. [PMID: 37113665 PMCID: PMC10126515 DOI: 10.3389/fbioe.2023.1157243] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2023] [Accepted: 03/31/2023] [Indexed: 04/29/2023] Open
Abstract
Microbial chain elongation has emerged as a valuable bioprocess for obtaining marketable products, such as medium chain fatty acids usable in several industrial applications, from organic waste. The understanding of the microbiology and microbial ecology in these systems is crucial to apply these microbiomes in reliable production processes controlling microbial pathways to promote favourable metabolic processes, which will in turn increase product specificity and yields. In this research, the dynamics, cooperation/competition and potentialities of bacterial communities involved in the long-term lactate-based chain elongation process from food waste extract were evaluated under different operating conditions by DNA/RNA amplicon sequencing and functional profile prediction. The feeding strategies and the applied organic loading rates strongly affected the microbial community composition. The use of food waste extract promoted the selection of primary fermenters (i.e., Olsenella, Lactobacillus) responsible for the in situ production of electron donors (i.e., lactate). The discontinuous feeding and the organic loading rate 15 gCOD L-1 d-1 selected the best performing microbiome in which microbes coexist and cooperate to complete the chain elongation process. Both at DNA and RNA level, this microbiome was composed by the lactate producer Olsenella, the short chain fatty acids producers Anaerostipes, Clostridium sensu stricto 7, C. sensu stricto 12, Corynebacterium, Erysipelotrichaceae UCG-004, F0332, Leuconostoc, and the chain elongator Caproiciproducens. This microbiome also showed the highest predicted abundance of short-chain acyl-CoA dehydrogenase, the functional enzyme responsible for the chain elongation process. The combined approach herein used allowed to study the microbial ecology of chain elongation process from food waste by identifying the main functional groups, establishing the presence of potential biotic interactions within the microbiomes, and predicting metabolic potentialities. This study provided pivotal indications for the selection of high-performance microbiome involved in caproate production from food waste that can serve as a basis for further improving system performance and engineering the process scale-up.
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Zhu X, Huang H, He Y, Wang X, Jia J, Feng X, Li D, Li H. A preliminary study on the feasibility of industrialization for n-caproic acid recovery from food wastewater: From lab to pilot. BIORESOURCE TECHNOLOGY 2022; 366:128154. [PMID: 36270389 DOI: 10.1016/j.biortech.2022.128154] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/07/2022] [Revised: 10/12/2022] [Accepted: 10/13/2022] [Indexed: 06/16/2023]
Abstract
Food wastewater is associated with greenhouse gas emission and has a significant water footprint. Here, the platform chemical n-caproate was recovered from liquor brewing wastewater at maximum and mean concentrations of 26.4 g/L and 17.0 ± 4.3 g/L, respectively, after 377 d operation. Laboratory-scale lactate-driven chain elongation (CE) process was implemented first. Taxonomic composition and metagenomic data analyses revealed that Caproiciproducens (e.g., Ruminococcaceae bacterium CPB6) and bacteria affiliated with Lachnospiraceae transformed lactate to n-caproate by reverse β-oxidation and/or fatty acid biosynthesis. The lactate-driven CE process was then scaled up from 2.5 L to 500 L and achieved a n-caproate production of 14.5 ± 0.6 g/L within 96 h. n-Caproic acid was extracted at a concentration and purity of 815.9 ± 8.3 g/L and 88.6 ± 8.9 %, respectively. The present study demonstrated a commercially viable strategy for resource recovery and carbon fixation from food waste streams.
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Affiliation(s)
- Xiaoyu Zhu
- CAS Key Laboratory of Environmental and Applied Microbiology, Environmental Microbiology Key Laboratory of Sichuan Province, Chengdu Institute of Biology, Chinese Academy of Sciences, Chengdu 610041, PR China; University of Chinese Academy of Sciences, Beijing 100864, PR China.
| | - Huanhuan Huang
- CAS Key Laboratory of Environmental and Applied Microbiology, Environmental Microbiology Key Laboratory of Sichuan Province, Chengdu Institute of Biology, Chinese Academy of Sciences, Chengdu 610041, PR China; University of Chinese Academy of Sciences, Beijing 100864, PR China
| | - Yong He
- CAS Key Laboratory of Environmental and Applied Microbiology, Environmental Microbiology Key Laboratory of Sichuan Province, Chengdu Institute of Biology, Chinese Academy of Sciences, Chengdu 610041, PR China; University of Chinese Academy of Sciences, Beijing 100864, PR China
| | - Xinyu Wang
- CAS Key Laboratory of Environmental and Applied Microbiology, Environmental Microbiology Key Laboratory of Sichuan Province, Chengdu Institute of Biology, Chinese Academy of Sciences, Chengdu 610041, PR China; University of Chinese Academy of Sciences, Beijing 100864, PR China; Guangxi Key Laboratory of Environmental Pollution Control Theory and Technology, Guilin University of Technology, Guilin 541004, PR China
| | - Jia Jia
- CAS Key Laboratory of Environmental and Applied Microbiology, Environmental Microbiology Key Laboratory of Sichuan Province, Chengdu Institute of Biology, Chinese Academy of Sciences, Chengdu 610041, PR China; University of Chinese Academy of Sciences, Beijing 100864, PR China
| | - Xin Feng
- CAS Key Laboratory of Environmental and Applied Microbiology, Environmental Microbiology Key Laboratory of Sichuan Province, Chengdu Institute of Biology, Chinese Academy of Sciences, Chengdu 610041, PR China; University of Chinese Academy of Sciences, Beijing 100864, PR China
| | - Dong Li
- CAS Key Laboratory of Environmental and Applied Microbiology, Environmental Microbiology Key Laboratory of Sichuan Province, Chengdu Institute of Biology, Chinese Academy of Sciences, Chengdu 610041, PR China; University of Chinese Academy of Sciences, Beijing 100864, PR China
| | - Haixiang Li
- Guangxi Key Laboratory of Environmental Pollution Control Theory and Technology, Guilin University of Technology, Guilin 541004, PR China
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11
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Revealing the Characteristics of Glucose- and Lactate-Based Chain Elongation for Caproate Production by Caproicibacterium lactatifermentans through Transcriptomic, Bioenergetic, and Regulatory Analyses. mSystems 2022; 7:e0053422. [PMID: 36073803 PMCID: PMC9600882 DOI: 10.1128/msystems.00534-22] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Caproate, an important medium-chain fatty acid, can only be synthesized by limited bacterial species by using ethanol, lactate, or certain saccharides. Caproicibacterium lactatifermentans is a promising caproate producer due to its glucose and lactate utilization capabilities. However, the global cellular responses of this bacterium to different carbon sources were not well understood. Here, C. lactatifermentans showed robust growth on glucose but more active caproate synthesis on lactate. Comparative transcriptome revealed that the genes involved in reverse β-oxidation for caproate synthesis and V-type ATPase-dependent ATP generation were upregulated under lactate condition, while several genes responsible for biomass synthesis were upregulated under glucose condition. Based on metabolic pathway reconstructions and bioenergetics analysis, the biomass accumulation on glucose condition may be supported by sufficient supplies of ATP and metabolite intermediates via glycolysis. In contrast, the ATP yield per glucose equivalent from lactate conversion into caproate was only 20% of that from glucose. Thus, the upregulation of the reverse β-oxidation genes may be essential for cell survival under lactate conditions. Furthermore, the remarkably decreased lactate utilization was observed after glucose acclimatization, indicating the negative modulation of lactate utilization by glucose metabolism. Based on the cotranscription of the lactate utilization repressor gene lldR with sugar-specific PTS genes and the opposite expression patterns of lldR and lactate utilization genes, a novel regulatory mechanism of glucose-repressed lactate utilization mediated via lldR was proposed. The results of this study suggested the molecular mechanism underlying differential physiologic and metabolic characteristics of C. lactatifermentans grown on glucose and lactate. IMPORTANCE Caproicibacterium lactatifermentans is a unique and robust caproate-producing bacterium in the family Oscillospiraceae due to its lactate utilization capability, whereas its close relatives such as Caproicibacterium amylolyticum, Caproiciproducens galactitolivorans, and Caproicibacter fermentans cannot utilize lactate but produce lactate as the main fermentation end product. Moreover, C. lactatifermentans can also utilize several saccharides such as glucose and maltose. Although the metabolic versatility of the bacterium makes it to be a promising industrial caproate producer, the cellular responses of C. lactatifermentans to different carbon sources were unknown. Here, the molecular mechanisms of biomass synthesis supported by glucose utilization and the cell survival supported by lactate utilization were revealed. A novel insight into the regulatory machinery in which glucose negatively regulates lactate utilization was proposed. This study provides a valuable basis to control and optimize caproate production, which will contribute to achieving a circular economy and environmental sustainability.
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12
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Ma H, Wu W, Yu Z, Zhao J, Fu P, Xia C, Lam SS, Wang Q, Gao M. Medium-chain fatty acid production from Chinese liquor brewing yellow water by electro-fermentation: Division of fermentation process and segmented electrical stimulation. BIORESOURCE TECHNOLOGY 2022; 360:127510. [PMID: 35752258 DOI: 10.1016/j.biortech.2022.127510] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/06/2022] [Revised: 06/20/2022] [Accepted: 06/21/2022] [Indexed: 06/15/2023]
Abstract
Electro-fermentation (EF) has been proposed as a method to improve the yield of medium-chain fatty acid (MCFA). In this study, MCFA production from Chinese liquor wastewater (yellow water) was investigated and corresponding composite electron donors (lactate and ethanol in yellow water) were investigated by different electrical stimulation modes. The caproate yield under whole period electrical stimulation increased by 250.9% compared with open circuit. The oxidation-dominated and reduction-dominated periods of the fermentation process were divided, and the segmented electrical stimulation experiment showed the caproate yield under reduction-dominated EF system further increased by 288.5% compared with open circuit. The microbial diversity analysis demonstrated that Clostridium 12 might be enriched better by keeping open circuit during EDs consumption, meanwhile the bacteria with potential negative effects on CE were inhibited. The electrical stimulation mode of EF process was optimized and provided a new way to recycle organic wastewater.
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Affiliation(s)
- Hongzhi Ma
- Department of Environmental Science and Engineering, University of Science and Technology Beijing 100083, China; Beijing Key Laboratory of Resource-oriented Treatment of Industrial Pollutants, Beijing 100083, China.
| | - Wenyu Wu
- Department of Environmental Science and Engineering, University of Science and Technology Beijing 100083, China; Beijing Key Laboratory of Resource-oriented Treatment of Industrial Pollutants, Beijing 100083, China
| | - Ziqiang Yu
- Department of Environmental Science and Engineering, University of Science and Technology Beijing 100083, China; Beijing Key Laboratory of Resource-oriented Treatment of Industrial Pollutants, Beijing 100083, China
| | - Jihua Zhao
- Department of Environmental Science and Engineering, University of Science and Technology Beijing 100083, China; Beijing Key Laboratory of Resource-oriented Treatment of Industrial Pollutants, Beijing 100083, China
| | - Penglu Fu
- Department of Environmental Science and Engineering, University of Science and Technology Beijing 100083, China; Beijing Key Laboratory of Resource-oriented Treatment of Industrial Pollutants, Beijing 100083, China
| | - Changlei Xia
- Jiangsu Co-Innovation Center of Efficient Processing and Utilization of Forest Resources, International Innovation Center for Forest Chemicals and Materials, College of Materials Science and Engineering, Nanjing Forestry University, Nanjing, Jiangsu 210037, China
| | - Su Shiung Lam
- Jiangsu Co-Innovation Center of Efficient Processing and Utilization of Forest Resources, International Innovation Center for Forest Chemicals and Materials, College of Materials Science and Engineering, Nanjing Forestry University, Nanjing, Jiangsu 210037, China; Higher Institution Centre of Excellence (HICoE), Institute of Tropical Aquaculture and Fisheries (AKUATROP), University Malaysia Terengganu, 21030 Kuala Nerus, Terengganu, Malaysia
| | - Qunhui Wang
- Department of Environmental Science and Engineering, University of Science and Technology Beijing 100083, China; Beijing Key Laboratory of Resource-oriented Treatment of Industrial Pollutants, Beijing 100083, China
| | - Ming Gao
- Department of Environmental Science and Engineering, University of Science and Technology Beijing 100083, China; Beijing Key Laboratory of Resource-oriented Treatment of Industrial Pollutants, Beijing 100083, China
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13
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Metagenomes and Metagenome-Assembled Genomes from Microbiomes Metabolizing Thin Stillage from an Ethanol Biorefinery. Microbiol Resour Announc 2022; 11:e0029022. [PMID: 35862918 PMCID: PMC9387277 DOI: 10.1128/mra.00290-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Here, we report the metagenomes from five anaerobic bioreactors, operated under different conditions, that were fed carbohydrate-rich thin stillage from a corn starch ethanol plant. The putative functions of the abundant taxa identified here will inform future studies of microbial communities involved in valorizing this and other low-value agroindustrial residues.
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14
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Metagenomes and Metagenome-Assembled Genomes from Microbial Communities Fermenting Ultrafiltered Milk Permeate. Microbiol Resour Announc 2022; 11:e0029322. [PMID: 35770995 PMCID: PMC9302107 DOI: 10.1128/mra.00293-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Fermentative microbial communities can be utilized for the conversion of various agroindustrial residues into valuable chemicals. Here, we report 34 metagenomes from anaerobic bioreactors fed lactose-rich ultrafiltered milk permeate and 278 metagenome-assembled genomes (MAGs). These MAGs can inform future studies aimed at generating renewable chemicals from dairy and other agroindustrial residues.
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15
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Tang J, Dai K, Wang QT, Zheng SJ, Hong SD, Jianxiong Zeng R, Zhang F. Caproate production from xylose via the fatty acid biosynthesis pathway by genus Caproiciproducens dominated mixed culture fermentation. BIORESOURCE TECHNOLOGY 2022; 351:126978. [PMID: 35276377 DOI: 10.1016/j.biortech.2022.126978] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/15/2022] [Revised: 03/05/2022] [Accepted: 03/07/2022] [Indexed: 06/14/2023]
Abstract
Caproate production from organic wastes is deemed as a novel strategy in mixed culture fermtation (MCF). However, producing caproate from natural sugar of xylose by MCF is seldom reported and the metabolic pathway is still unclear. Thus, the caproate production from xylose was investigated in this study by mesophilic MCF. The results showed that the caproate concentration from xylose (10 g/L) was 1.2 ± 0.17 g/L (equal to 2.7 gCOD/L) under pH 5.0. Dosing extra ethanol of 5 g/L could slightly increase the caproate production by ∼ 30% (i.e., 1.6 g/L). While dosing extra acetate of 5 g/L negatively affected the caproate production, which was just 0.2 g/L. The microbial analysis illustrated that genus Caproiciproducens was a main identified caproate producer, occupying over 80% of enriched mixed culture. The fatty acid biosynthesis pathway was identified via metagenomic analysis. These unexpected differences extended the understanding of caproate production from organic wastes.
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Affiliation(s)
- Jie Tang
- Center of Wastewater Resource Recovery, College of Resources and Environment, Fujian Agriculture and Forestry University, Fuzhou, Fujian 350002, China
| | - Kun Dai
- Center of Wastewater Resource Recovery, College of Resources and Environment, Fujian Agriculture and Forestry University, Fuzhou, Fujian 350002, China
| | - Qing-Ting Wang
- Center of Wastewater Resource Recovery, College of Resources and Environment, Fujian Agriculture and Forestry University, Fuzhou, Fujian 350002, China
| | - Si-Jie Zheng
- Center of Wastewater Resource Recovery, College of Resources and Environment, Fujian Agriculture and Forestry University, Fuzhou, Fujian 350002, China
| | - Si-Di Hong
- Center of Wastewater Resource Recovery, College of Resources and Environment, Fujian Agriculture and Forestry University, Fuzhou, Fujian 350002, China
| | - Raymond Jianxiong Zeng
- Center of Wastewater Resource Recovery, College of Resources and Environment, Fujian Agriculture and Forestry University, Fuzhou, Fujian 350002, China
| | - Fang Zhang
- Center of Wastewater Resource Recovery, College of Resources and Environment, Fujian Agriculture and Forestry University, Fuzhou, Fujian 350002, China.
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16
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Liu B, Sträuber H, Saraiva J, Harms H, Silva SG, Kasmanas JC, Kleinsteuber S, Nunes da Rocha U. Machine learning-assisted identification of bioindicators predicts medium-chain carboxylate production performance of an anaerobic mixed culture. MICROBIOME 2022; 10:48. [PMID: 35331330 PMCID: PMC8952268 DOI: 10.1186/s40168-021-01219-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/28/2021] [Accepted: 12/17/2021] [Indexed: 05/10/2023]
Abstract
BACKGROUND The ability to quantitatively predict ecophysiological functions of microbial communities provides an important step to engineer microbiota for desired functions related to specific biochemical conversions. Here, we present the quantitative prediction of medium-chain carboxylate production in two continuous anaerobic bioreactors from 16S rRNA gene dynamics in enriched communities. RESULTS By progressively shortening the hydraulic retention time (HRT) from 8 to 2 days with different temporal schemes in two bioreactors operated for 211 days, we achieved higher productivities and yields of the target products n-caproate and n-caprylate. The datasets generated from each bioreactor were applied independently for training and testing machine learning algorithms using 16S rRNA genes to predict n-caproate and n-caprylate productivities. Our dataset consisted of 14 and 40 samples from HRT of 8 and 2 days, respectively. Because of the size and balance of our dataset, we compared linear regression, support vector machine and random forest regression algorithms using the original and balanced datasets generated using synthetic minority oversampling. Further, we performed cross-validation to estimate model stability. The random forest regression was the best algorithm producing more consistent results with median of error rates below 8%. More than 90% accuracy in the prediction of n-caproate and n-caprylate productivities was achieved. Four inferred bioindicators belonging to the genera Olsenella, Lactobacillus, Syntrophococcus and Clostridium IV suggest their relevance to the higher carboxylate productivity at shorter HRT. The recovery of metagenome-assembled genomes of these bioindicators confirmed their genetic potential to perform key steps of medium-chain carboxylate production. CONCLUSIONS Shortening the hydraulic retention time of the continuous bioreactor systems allows to shape the communities with desired chain elongation functions. Using machine learning, we demonstrated that 16S rRNA amplicon sequencing data can be used to predict bioreactor process performance quantitatively and accurately. Characterizing and harnessing bioindicators holds promise to manage reactor microbiota towards selection of the target processes. Our mathematical framework is transferrable to other ecosystem processes and microbial systems where community dynamics is linked to key functions. The general methodology used here can be adapted to data types of other functional categories such as genes, transcripts, proteins or metabolites. Video Abstract.
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Affiliation(s)
- Bin Liu
- Department of Environmental Microbiology, Helmholtz Centre for Environmental Research - UFZ, Leipzig, Germany
| | - Heike Sträuber
- Department of Environmental Microbiology, Helmholtz Centre for Environmental Research - UFZ, Leipzig, Germany
| | - João Saraiva
- Department of Environmental Microbiology, Helmholtz Centre for Environmental Research - UFZ, Leipzig, Germany
| | - Hauke Harms
- Department of Environmental Microbiology, Helmholtz Centre for Environmental Research - UFZ, Leipzig, Germany
| | - Sandra Godinho Silva
- Institute for Bioengineering and Biosciences, Department of Bioengineering, Instituto Superior Técnico Universidade de Lisboa, Lisbon, Portugal
| | - Jonas Coelho Kasmanas
- Department of Environmental Microbiology, Helmholtz Centre for Environmental Research - UFZ, Leipzig, Germany
- Institute of Mathematics and Computer Sciences, University of São Paulo, São Carlos, Brazil
- Department of Computer Science and Interdisciplinary Center of Bioinformatics, University of Leipzig, Leipzig, Germany
| | - Sabine Kleinsteuber
- Department of Environmental Microbiology, Helmholtz Centre for Environmental Research - UFZ, Leipzig, Germany.
| | - Ulisses Nunes da Rocha
- Department of Environmental Microbiology, Helmholtz Centre for Environmental Research - UFZ, Leipzig, Germany.
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17
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Kang S, Kim H, Jeon BS, Choi O, Sang BI. Chain elongation process for caproate production using lactate as electron donor in Megasphaera hexanoica. BIORESOURCE TECHNOLOGY 2022; 346:126660. [PMID: 34974100 DOI: 10.1016/j.biortech.2021.126660] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/31/2021] [Revised: 12/24/2021] [Accepted: 12/28/2021] [Indexed: 05/12/2023]
Abstract
Megasphaera hexnaoica is anaerobic bacteria who has well running reverse β-oxidation pathway. In previous study, the strain showed excellent production of medium chain carboxylic acids (MCCAs) using fructose as electron donor. In this study, chain elongation process study using lactate instead of fructose was conducted in M. hexnaoica fermentation. It was found that M. hexanoica can use lactate as electron donor in chain elongation process. 8.9 g/L caproate production was achieved in fermentation using lactate as sole electron donor. Compare to fructose condition, lactate as electron donor showed more than 3 times higher specific titer and specific productivity. In addition, when fructose and lactate were used as electron donor simultaneously, further improvement of MCCAs production was observed to achieve maximum caproate productivity of 20.9 g/L/day. Utilization of lactate as electron donor in M. hexanoica showed potential opportunity in chain elongation process.
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Affiliation(s)
- Seongcheol Kang
- Department of Chemical Engineering, Hanyang University, 222, Wangsimni-ro, Seongdong-gu, Seoul 04763, Republic of Korea
| | - Hyunjin Kim
- Department of Chemical Engineering, Hanyang University, 222, Wangsimni-ro, Seongdong-gu, Seoul 04763, Republic of Korea
| | - Byoung Seung Jeon
- Korea Institute of Ceramic Engineering and Technology (KICET), 202, Osongsaengmyeong 1-ro, Heungdeck-gu, Cheongju-si, Chungcheongbuk-do 28160, Republic of Korea
| | - Okkyoung Choi
- Department of Chemical Engineering, Hanyang University, 222, Wangsimni-ro, Seongdong-gu, Seoul 04763, Republic of Korea
| | - Byoung-In Sang
- Department of Chemical Engineering, Hanyang University, 222, Wangsimni-ro, Seongdong-gu, Seoul 04763, Republic of Korea.
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18
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Gao J, Qin J, Ye F, Ding F, Liu G, Li A, Ren C, Xu Y. Constructing simplified microbial consortia to improve the key flavour compounds during strong aroma-type Baijiu fermentation. Int J Food Microbiol 2022; 369:109594. [DOI: 10.1016/j.ijfoodmicro.2022.109594] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2021] [Revised: 02/08/2022] [Accepted: 02/22/2022] [Indexed: 11/25/2022]
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19
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Adaptability of a caproate-producing bacterium contributes to its dominance in an anaerobic fermentation system. Appl Environ Microbiol 2021; 87:e0120321. [PMID: 34378978 DOI: 10.1128/aem.01203-21] [Citation(s) in RCA: 25] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The transformation of diverse feedstocks into medium-chain fatty acids (MCFAs) by mixed cultures is a promising biorefinery route because of the high value of MCFAs. A particular concern is how to maintain the microbial consortia in mixed cultures to achieve stable MCFA production. Chinese strong aroma-type liquor (Baijiu) fermentation system continually produces caproic acid for decades through a spontaneous inoculation of anaerobes from pit mud into fermented grains. Therefore, illuminating the dominant caproate-producing bacterium (CPB) in pit mud and how the CPB sustains in the spontaneous fermentation system will benefit to reveal the microbiological mechanisms of the stable caproate production. Here, we examined pit mud samples across four Chinese strong aroma-type Baijiu producing areas and found that a caproate-producing Caproicibacterium sp. was widely distributed in these distilleries with relative abundance ranging from 1.4% to 35.5% and an average abundance of 11.4%. Through controlling carbon source availability, we achieved different simplified caproate-producing consortia and found that the growth advantage of Caproicibacterium sp. was highly dependent on glucose. Then two strains, named Caproicibacterium sp. LBM19010 and Caproicibacterium sp. JNU-WLY1368, were isolated from pit mud of two regions. The metabolic versatility of this bacterium utilizing starch, maltose, glucose and lactate reflected its adaptability to the fermentation environment where these carbon sources coexist. The simultaneous utilization of glucose and lactate contributed to the balance between cell growth and pH homeostasis. This study reveals that multiple adaptation strategies employed by the predominant CPB promotes its stability and dominance in a saccharide- and lactate-rich anaerobic habitat. IMPORTANCE Chinese strong aroma-type liquor (Baijiu) fermentation environment is a typical medium-chain fatty acid producing system with complex nutrients. Although several studies have revealed the correlation between microbial community composition and abiotic factors, the adaptation mechanisms of dominant species to abiotic environment are still unknown in this special anaerobic habitat. This study identified the predominant CPB in Chinese strong aroma-type Baijiu fermentation system. Metabolic versatility and flexibility of the dominant CPB with a small-size genome indicated that this bacterium can effectively exploit available carbon and nitrogen sources, which could be a key factor to promote its ecological success in a multi-species environment. The understanding of growth and metabolic features of CPB responsible for its dominance in microbial community will not only contribute to the improvement of Chinese strong aroma-type Baijiu production but also expand its potential industrial applications in caproate production.
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