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Undiandeye J, Gallegos D, Bonatelli ML, Kleinsteuber S, Bin-Hudari MS, Abdulkadir N, Stinner W, Sträuber H. Medium-chain carboxylates production from plant waste: kinetic study and effect of an enriched microbiome. BIOTECHNOLOGY FOR BIOFUELS AND BIOPRODUCTS 2024; 17:79. [PMID: 38867271 PMCID: PMC11167882 DOI: 10.1186/s13068-024-02528-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/22/2024] [Accepted: 06/04/2024] [Indexed: 06/14/2024]
Abstract
BACKGROUND The need for addition of external electron donors such as ethanol or lactate impairs the economic viability of chain elongation (CE) processes for the production of medium-chain carboxylates (MCC). However, using feedstocks with inherent electron donors such as silages of waste biomass can improve the economics. Moreover, the use of an appropriate inoculum is critical to the overall efficiency of the CE process, as the production of a desired MCC can significantly be influenced by the presence or absence of specific microorganisms and their metabolic interactions. Beyond, it is necessary to generate data that can be used for reactor design, simulation and optimization of a given CE process. Such data can be obtained using appropriate mathematical models to predict the dynamics of the CE process. RESULTS In batch experiments using silages of sugar beet leaves, cassava leaves, and Elodea/wheat straw as substrates, caproate was the only MCC produced with maximum yields of 1.97, 3.48, and 0.88 g/kgVS, respectively. The MCC concentrations were accurately predicted with the modified Gompertz model. In a semi-continuous fermentation with ensiled sugar beet leaves as substrate and digestate from a biogas reactor as the sole inoculum, a prolonged lag phase of 7 days was observed for the production of MCC (C6-C8). The lag phase was significantly shortened by at least 4 days when an enriched inoculum was added to the system. With the enriched inoculum, an MCC yield of 93.67 g/kgVS and a productivity of 2.05 gMCC/L/d were achieved. Without the enriched inoculum, MCC yield and productivity were 43.30 g/kgVS and 0.95 gMCC/L/d, respectively. The higher MCC production was accompanied by higher relative abundances of Lachnospiraceae and Eubacteriaceae. CONCLUSIONS Ensiled waste biomass is a suitable substrate for MCC production using CE. For an enhanced production of MCC from ensiled sugar beet leaves, the use of an enriched inoculum is recommended for a fast process start and high production performance.
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Affiliation(s)
- Jerome Undiandeye
- Department of Biochemical Conversion, DBFZ Deutsches Biomasseforschungszentrum Gemeinnützige GmbH, 04347, Leipzig, Germany.
- Department of Chemical Engineering, University of Port Harcourt, PMB 5323, Port Harcourt, Nigeria.
| | - Daniela Gallegos
- Department of Biochemical Conversion, DBFZ Deutsches Biomasseforschungszentrum Gemeinnützige GmbH, 04347, Leipzig, Germany
| | - Maria L Bonatelli
- Department of Microbial Biotechnology, Helmholtz Centre for Environmental Research - UFZ, 04318, Leipzig, Germany
| | - Sabine Kleinsteuber
- Department of Microbial Biotechnology, Helmholtz Centre for Environmental Research - UFZ, 04318, Leipzig, Germany
| | - Mohammad Sufian Bin-Hudari
- Department of Isotope Biogeochemistry, Helmholtz Centre for Environmental Research - UFZ, 04318, Leipzig, Germany
| | - Nafi'u Abdulkadir
- Research Unit for Comparative Microbiome Analysis, Helmholtz Munich, German Research Center for Environmental Health, 85764, Neuherberg, Germany
- Department of Microbiology, Sokoto State University, Sokoto, 852101, Nigeria
| | - Walter Stinner
- Department of Biochemical Conversion, DBFZ Deutsches Biomasseforschungszentrum Gemeinnützige GmbH, 04347, Leipzig, Germany
| | - Heike Sträuber
- Department of Microbial Biotechnology, Helmholtz Centre for Environmental Research - UFZ, 04318, Leipzig, Germany
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Ulčar B, Regueira A, Podojsteršek M, Boon N, Ganigué R. Why do lactic acid bacteria thrive in chain elongation microbiomes? Front Bioeng Biotechnol 2024; 11:1291007. [PMID: 38274012 PMCID: PMC10809155 DOI: 10.3389/fbioe.2023.1291007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2023] [Accepted: 12/11/2023] [Indexed: 01/27/2024] Open
Abstract
Efficient waste management is necessary to transition towards a more sustainable society. An emerging trend is to use mixed culture biotechnology to produce chemicals from organic waste. Insights into the metabolic interactions between community members and their growth characterization are needed to mediate knowledge-driven bioprocess development and optimization. Here, a granular sludge bioprocess for the production of caproic acid through sugar-based chain elongation metabolism was established. Lactic acid and chain-elongating bacteria were identified as the two main functional guilds in the granular community. The growth features of the main community representatives (isolate Limosilactobacillus musocae G03 for lactic acid bacteria and type strain Caproiciproducens lactatifermentans for chain-elongating bacteria) were characterized. The measured growth rates of lactic acid bacteria (0.051 ± 0.005 h-1) were two times higher than those of chain-elongating bacteria (0.026 ± 0.004 h-1), while the biomass yields of lactic acid bacteria (0.120 ± 0.005 g biomass/g glucose) were two times lower than that of chain-elongating bacteria (0.239 ± 0.007 g biomass/g glucose). This points towards differential growth strategies, with lactic acid bacteria resembling that of a r-strategist and chain-elongating bacteria resembling that of a K-strategist. Furthermore, the half-saturation constant of glucose for L. mucosae was determined to be 0.35 ± 0.05 g/L of glucose. A linear trend of caproic acid inhibition on the growth of L. mucosae was observed, and the growth inhibitory caproic acid concentration was predicted to be 13.6 ± 0.5 g/L, which is the highest reported so far. The pre-adjustment of L. mucosae to 4 g/L of caproic acid did not improve the overall resistance to it, but did restore the growth rates at low caproic acid concentrations (1-4 g/L) to the baseline values (i.e., growth rate at 0 g/L of caproic acid). High resistance to caproic acid enables lactic acid bacteria to persist and thrive in the systems intended for caproic acid production. Here, insights into the growth of two main functional guilds of sugar-based chain elongation systems are provided which allows for a better understanding of their interactions and promotes future bioprocess design and optimization.
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Affiliation(s)
- Barbara Ulčar
- Center for Microbial Ecology and Technology (CMET), Department of Biotechnology, Ghent University, Gent, Belgium
- Center for Advanced Process Technology for Urban Resource Recovery (CAPTURE), Gent, Belgium
| | - Alberte Regueira
- Center for Microbial Ecology and Technology (CMET), Department of Biotechnology, Ghent University, Gent, Belgium
- Center for Advanced Process Technology for Urban Resource Recovery (CAPTURE), Gent, Belgium
- Department of Chemical Engineering, Universidade de Santiago de Compostela, Santiago de Compostela, Spain
| | - Maja Podojsteršek
- Center for Microbial Ecology and Technology (CMET), Department of Biotechnology, Ghent University, Gent, Belgium
- Center for Advanced Process Technology for Urban Resource Recovery (CAPTURE), Gent, Belgium
| | - Nico Boon
- Center for Microbial Ecology and Technology (CMET), Department of Biotechnology, Ghent University, Gent, Belgium
- Center for Advanced Process Technology for Urban Resource Recovery (CAPTURE), Gent, Belgium
| | - Ramon Ganigué
- Center for Microbial Ecology and Technology (CMET), Department of Biotechnology, Ghent University, Gent, Belgium
- Center for Advanced Process Technology for Urban Resource Recovery (CAPTURE), Gent, Belgium
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3
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Liu B, Sträuber H, Centler F, Harms H, da Rocha UN, Kleinsteuber S. Functional Redundancy Secures Resilience of Chain Elongation Communities upon pH Shifts in Closed Bioreactor Ecosystems. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2023; 57:18350-18361. [PMID: 37097211 PMCID: PMC10666546 DOI: 10.1021/acs.est.2c09573] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/20/2022] [Revised: 04/13/2023] [Accepted: 04/13/2023] [Indexed: 06/19/2023]
Abstract
For anaerobic mixed cultures performing microbial chain elongation, it is unclear how pH alterations affect the abundance of key players, microbial interactions, and community functioning in terms of medium-chain carboxylate yields. We explored pH effects on mixed cultures enriched in continuous anaerobic bioreactors representing closed model ecosystems. Gradual pH increase from 5.5 to 6.5 induced dramatic shifts in community composition, whereas product range and yields returned to previous states after transient fluctuations. To understand community responses to pH perturbations over long-term reactor operation, we applied Aitchison PCA clustering, linear mixed-effects models, and random forest classification on 16S rRNA gene amplicon sequencing and process data. Different pH preferences of two key chain elongation species─one Clostridium IV species related to Ruminococcaceae bacterium CPB6 and one Clostridium sensu stricto species related to Clostridium luticellarii─were determined. Network analysis revealed positive correlations of Clostridium IV with lactic acid bacteria, which switched from Olsenella to Lactobacillus along the pH increase, illustrating the plasticity of the food web in chain elongation communities. Despite long-term cultivation in closed systems over the pH shift experiment, the communities retained functional redundancy in fermentation pathways, reflected by the emergence of rare species and concomitant recovery of chain elongation functions.
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Affiliation(s)
- Bin Liu
- Department
of Environmental Microbiology, Helmholtz
Centre for Environmental Research − UFZ, 04318 Leipzig, Germany
- KU
Leuven, Department of Microbiology,
Immunology and Transplantation, Rega Institute for Medical Research,
Laboratory of Molecular Bacteriology, BE-3000 Leuven, Belgium
| | - Heike Sträuber
- Department
of Environmental Microbiology, Helmholtz
Centre for Environmental Research − UFZ, 04318 Leipzig, Germany
| | - Florian Centler
- Department
of Environmental Microbiology, Helmholtz
Centre for Environmental Research − UFZ, 04318 Leipzig, Germany
- School
of Life Sciences, University of Siegen, 57076 Siegen, Germany
| | - Hauke Harms
- Department
of Environmental Microbiology, Helmholtz
Centre for Environmental Research − UFZ, 04318 Leipzig, Germany
| | - Ulisses Nunes da Rocha
- Department
of Environmental Microbiology, Helmholtz
Centre for Environmental Research − UFZ, 04318 Leipzig, Germany
| | - Sabine Kleinsteuber
- Department
of Environmental Microbiology, Helmholtz
Centre for Environmental Research − UFZ, 04318 Leipzig, Germany
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Wang Q, Yang N, Cai Y, Zhang R, Wu Y, Ma W, Fu C, Zhang P, Zhang G. Advances in understanding entire process of medium chain carboxylic acid production from organic wastes via chain elongation. CHEMOSPHERE 2023; 339:139723. [PMID: 37543231 DOI: 10.1016/j.chemosphere.2023.139723] [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: 04/30/2023] [Revised: 07/22/2023] [Accepted: 08/01/2023] [Indexed: 08/07/2023]
Abstract
Chain elongation is an environmentally friendly biological technology capable of converting organic wastes into medium chain carboxylic acids (MCCAs). This review aims to offer a comprehensive analysis of MCCA production from organic wastes via chain elongation. Seven kinds of organic wastes are introduced and classified as easily degradable and hardly degradable. Among them, food waste, fruit and vegetable waste are the most potential organic wastes for MCCA production. Combined pretreatment technologies should be encouraged for the pretreatment of hardly degradable organic wastes. Furthermore, the mechanisms during MCCA production are analyzed, and the key influencing factors are evaluated, which affect the MCCA production and chain elongation efficiency indirectly. Extracting MCCA simultaneously is the most important way to improve MCCA production efficiency, and technologies for sequentially extracting different kinds of MCCAs are recommended. Finally, some perspectives for future chain elongation researches are proposed to promote the large-scale application of chain elongation.
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Affiliation(s)
- Qingyan Wang
- Beijing Key Lab for Source Control Technology of Water Pollution, College of Environmental Science and Engineering, Beijing Forestry University, Beijing, 100083, China; Engineering Research Center for Water Pollution Source Control & Eco-remediation, College of Environmental Science and Engineering, Beijing Forestry University, Beijing, 100083, China
| | - Nan Yang
- Beijing Key Lab for Source Control Technology of Water Pollution, College of Environmental Science and Engineering, Beijing Forestry University, Beijing, 100083, China; Engineering Research Center for Water Pollution Source Control & Eco-remediation, College of Environmental Science and Engineering, Beijing Forestry University, Beijing, 100083, China
| | - Yajing Cai
- Beijing Key Lab for Source Control Technology of Water Pollution, College of Environmental Science and Engineering, Beijing Forestry University, Beijing, 100083, China; Engineering Research Center for Water Pollution Source Control & Eco-remediation, College of Environmental Science and Engineering, Beijing Forestry University, Beijing, 100083, China
| | - Ru Zhang
- Beijing Key Lab for Source Control Technology of Water Pollution, College of Environmental Science and Engineering, Beijing Forestry University, Beijing, 100083, China; Engineering Research Center for Water Pollution Source Control & Eco-remediation, College of Environmental Science and Engineering, Beijing Forestry University, Beijing, 100083, China
| | - Yan Wu
- School of Environmental and Chemical Engineering, Chongqing Three Gorges University, Chongqing, 404632, China
| | - Weifang Ma
- Beijing Key Lab for Source Control Technology of Water Pollution, College of Environmental Science and Engineering, Beijing Forestry University, Beijing, 100083, China; Engineering Research Center for Water Pollution Source Control & Eco-remediation, College of Environmental Science and Engineering, Beijing Forestry University, Beijing, 100083, China
| | - Chuan Fu
- School of Environmental and Chemical Engineering, Chongqing Three Gorges University, Chongqing, 404632, China
| | - Panyue Zhang
- Beijing Key Lab for Source Control Technology of Water Pollution, College of Environmental Science and Engineering, Beijing Forestry University, Beijing, 100083, China; Engineering Research Center for Water Pollution Source Control & Eco-remediation, College of Environmental Science and Engineering, Beijing Forestry University, Beijing, 100083, China; School of Environmental and Chemical Engineering, Chongqing Three Gorges University, Chongqing, 404632, China.
| | - Guangming Zhang
- School of Energy & Environmental Engineering, Hebei University of Technology, Tianjin, 300130, China.
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5
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López-Gálvez J, Schiessl K, Besmer MD, Bruckmann C, Harms H, Müller S. Development of an Automated Online Flow Cytometry Method to Quantify Cell Density and Fingerprint Bacterial Communities. Cells 2023; 12:1559. [PMID: 37371029 DOI: 10.3390/cells12121559] [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: 04/20/2023] [Revised: 05/09/2023] [Accepted: 06/02/2023] [Indexed: 06/29/2023] Open
Abstract
Cell density is an important factor in all microbiome research, where interactions are of interest. It is also the most important parameter for the operation and control of most biotechnological processes. In the past, cell density determination was often performed offline and manually, resulting in a delay between sampling and immediate data processing, preventing quick action. While there are now some online methods for rapid and automated cell density determination, they are unable to distinguish between the different cell types in bacterial communities. To address this gap, an online automated flow cytometry procedure is proposed for real-time high-resolution analysis of bacterial communities. On the one hand, it allows for the online automated calculation of cell concentrations and, on the other, for the differentiation between different cell subsets of a bacterial community. To achieve this, the OC-300 automation device (onCyt Microbiology, Zürich, Switzerland) was coupled with the flow cytometer CytoFLEX (Beckman Coulter, Brea, USA). The OC-300 performs the automatic sampling, dilution, fixation and 4',6-diamidino-2-phenylindole (DAPI) staining of a bacterial sample before sending it to the CytoFLEX for measurement. It is demonstrated that this method can reproducibly measure both cell density and fingerprint-like patterns of bacterial communities, generating suitable data for powerful automated data analysis and interpretation pipelines. In particular, the automated, high-resolution partitioning of clustered data into cell subsets opens up the possibility of correlation analysis to identify the operational or abiotic/biotic causes of community disturbances or state changes, which can influence the interaction potential of organisms in microbiomes or even affect the performance of individual organisms.
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Affiliation(s)
- Juan López-Gálvez
- Department of Environmental Microbiology, Helmholtz-Centre for Environmental Research, Permoserstraße 15, D-04318 Leipzig, Germany
| | | | - Michael D Besmer
- onCyt Microbiology AG, Marchwartstrasse 61, 8038 Zürich, Switzerland
| | - Carmen Bruckmann
- Department of Environmental Microbiology, Helmholtz-Centre for Environmental Research, Permoserstraße 15, D-04318 Leipzig, Germany
| | - Hauke Harms
- Department of Environmental Microbiology, Helmholtz-Centre for Environmental Research, Permoserstraße 15, D-04318 Leipzig, Germany
| | - Susann Müller
- Department of Environmental Microbiology, Helmholtz-Centre for Environmental Research, Permoserstraße 15, D-04318 Leipzig, Germany
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6
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Brodowski F, Łężyk M, Gutowska N, Kabasakal T, Oleskowicz-Popiel P. Influence of lactate to acetate ratio on biological production of medium chain carboxylates via open culture fermentation. THE SCIENCE OF THE TOTAL ENVIRONMENT 2022; 851:158171. [PMID: 35988608 DOI: 10.1016/j.scitotenv.2022.158171] [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: 07/01/2022] [Revised: 08/08/2022] [Accepted: 08/16/2022] [Indexed: 06/15/2023]
Abstract
Waste valorisation via biological production of widely used in the industry medium chain carboxylates (MCCs) via open culture fermentation (OCF) could be a promising alternative to the commonly used anaerobic digestion. Lactate-rich waste streams are considered as valuable substrates for carboxylate chain elongation (CE), however, there are certain limitations related to the production efficiency. Acetate produced and accumulated in the acetogenesis plays an important role in CE, i.e. acetate is elongated to butyrate and then to caproate which is most popular MCC. Henceforth, it was investigated whether the ratio of lactate to acetate (L:A) affected carboxylates yields and product distribution in the lactate-based CE in OCF. The tested L:A ratios influenced carboxylates selectivity in batch trials. In the ones with lactate as the sole carbon source, propionate production was predominant but when a higher relative acetate concentration was used, the production of butyrate and CE to caproate was favored. The co-utilization of lactate and acetate in a continuous process increased the production of butyrate and caproate compared to the phase with lactate as the sole carbon source, however, controlling the relative concentration of lactate and acetate during co-utilization was not an effective strategy for increasing caproate production. 16S rRNA gene amplicon reads mapping to Caproiciproducens were the most abundant in samples collected throughout the continuous processes regardless of the L:A ratios.
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Affiliation(s)
- Filip Brodowski
- Water Supply and Bioeconomy Division, Faculty of Environmental Engineering and Energy, Poznan University of Technology, Berdychowo 4, 60-965 Poznan, Poland
| | - Mateusz Łężyk
- Water Supply and Bioeconomy Division, Faculty of Environmental Engineering and Energy, Poznan University of Technology, Berdychowo 4, 60-965 Poznan, Poland
| | - Natalia Gutowska
- Water Supply and Bioeconomy Division, Faculty of Environmental Engineering and Energy, Poznan University of Technology, Berdychowo 4, 60-965 Poznan, Poland
| | - Tugba Kabasakal
- Water Supply and Bioeconomy Division, Faculty of Environmental Engineering and Energy, Poznan University of Technology, Berdychowo 4, 60-965 Poznan, Poland
| | - Piotr Oleskowicz-Popiel
- Water Supply and Bioeconomy Division, Faculty of Environmental Engineering and Energy, Poznan University of Technology, Berdychowo 4, 60-965 Poznan, Poland.
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7
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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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8
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Gazzola G, Maria Braguglia C, Crognale S, Gallipoli A, Mininni G, Piemonte V, Rossetti S, Tonanzi B, Gianico A. Biorefining food waste through the anaerobic conversion of endogenous lactate into caproate: A fragile balance between microbial substrate utilization and product inhibition. WASTE MANAGEMENT (NEW YORK, N.Y.) 2022; 150:328-338. [PMID: 35907330 DOI: 10.1016/j.wasman.2022.07.031] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/11/2022] [Revised: 06/27/2022] [Accepted: 07/21/2022] [Indexed: 06/15/2023]
Abstract
New technologies development and renewable source exploitation are key tools to realize the European Green Deal and to boost the bio-based economy. In this context, fermentation of organic residues as food waste is an efficient method to obtain marketable products such as carboxylic acids widely applied in industrial production. Under favourable thermodynamic conditions, short chain fatty acids deriving from primary fermentation could be biologically converted into medium-chain fatty acids as caproate via chain elongation (CE) process, by using ethanol or lactate as electron donors. This study evaluates the effectivity of producing caproate from Food Waste extract rich in organics with in situ electron donor production. The test carried out at OLR 15 gCOD L-1d-1 showed high Volatile Fatty Acids (from acetic to caproic acid) yields (0.37 g g-1CODfed), with a maximum caproate concentration of 8 g L-1. The associated microbiome was composed by lactate-producing bacteria (Corynebacterium, Lactobacillus, and Olsenella) and by chain elongators (Clostridiaceae and Caproiciproducens). By stressing the system with OLR increase up to 20 gCOD L-1d-1, the CE process was inhibited by the high concentration of caproate (low occurrence of Clostridiaceae and Caproiciproducens). Nevertheless, after few days of stop-feeding regime imposed to the system, the microbiome restored its capability to proceed with lactate-based CE pathways. Different batch tests carried out with the inhibited biomass at increasing initial caproate concentration confirmed its impact on lactate utilization kinetics.
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Affiliation(s)
- Giulio Gazzola
- Water Research Institute, National Research Council of Italy, CNR-IRSA, Area della Ricerca RM1, Via Salaria km 29.300, 00015 Monterotondo, Roma, Italy
| | - Camilla Maria Braguglia
- Water Research Institute, National Research Council of Italy, CNR-IRSA, Area della Ricerca RM1, Via Salaria km 29.300, 00015 Monterotondo, Roma, Italy
| | - Simona Crognale
- Water Research Institute, National Research Council of Italy, CNR-IRSA, Area della Ricerca RM1, Via Salaria km 29.300, 00015 Monterotondo, Roma, Italy
| | - Agata Gallipoli
- Water Research Institute, National Research Council of Italy, CNR-IRSA, Area della Ricerca RM1, Via Salaria km 29.300, 00015 Monterotondo, Roma, Italy
| | - Giuseppe Mininni
- Water Research Institute, National Research Council of Italy, CNR-IRSA, Area della Ricerca RM1, Via Salaria km 29.300, 00015 Monterotondo, Roma, Italy
| | - Vincenzo Piemonte
- Faculty of Engineering, University Campus Bio-Medico, Via Alvaro del Portillo, 21, 00128 Roma, Italy
| | - Simona Rossetti
- Water Research Institute, National Research Council of Italy, CNR-IRSA, Area della Ricerca RM1, Via Salaria km 29.300, 00015 Monterotondo, Roma, Italy
| | - Barbara Tonanzi
- Water Research Institute, National Research Council of Italy, CNR-IRSA, Area della Ricerca RM1, Via Salaria km 29.300, 00015 Monterotondo, Roma, Italy
| | - Andrea Gianico
- Water Research Institute, National Research Council of Italy, CNR-IRSA, Area della Ricerca RM1, Via Salaria km 29.300, 00015 Monterotondo, Roma, Italy.
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9
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Mariën Q, Ulčar B, Verleyen J, Vanthuyne B, Ganigué R. High-rate conversion of lactic acid-rich streams to caproic acid in a fermentative granular system. BIORESOURCE TECHNOLOGY 2022; 355:127250. [PMID: 35562021 DOI: 10.1016/j.biortech.2022.127250] [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: 03/17/2022] [Revised: 04/26/2022] [Accepted: 04/27/2022] [Indexed: 06/15/2023]
Abstract
Lactic acid-driven chain elongation enables upgrading low-value organic streams into caproic acid. Recently, volumetric production rates over 0.5 g L-1 h-1have been reported for carbohydrate-rich streams in expanded granular sludge bed (EGSB) reactors. However, many target streams contain mixtures of carbohydrates and lactic acid, and little is known about their impact on product profile and microbial ecology, or the importance of carbohydrates as substrate to achieve high rates. This manuscript investigated varying glucose-to-lactate ratios and observed that decreasing glucose-content eliminated odd-chain by-products, while glucose omission required acetic acid addition to support lactic acid conversion. Decreasing the glucose-content fed resulted in decreasing amounts of granular biomass, with the disappearance of granules when no glucose was fed. Lowering the HRT to 0.3 days while feeding only lactic and acetic acid likely triggered re-granulation, enabling the highest lactic acid-driven caproic acid production rates reported thus far at 16.4 ± 1.7 g L-1 d-1.
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Affiliation(s)
- Quinten Mariën
- Center for Microbial Ecology and Technology (CMET), Ghent University, Coupure Links 653, 9000 Ghent, Belgium; Center for Advanced Process Technology for Urban Resource Recovery (CAPTURE), Frieda Saeysstraat 1, 9000 Ghent, Belgium
| | - Barbara Ulčar
- Center for Microbial Ecology and Technology (CMET), Ghent University, Coupure Links 653, 9000 Ghent, Belgium; Center for Advanced Process Technology for Urban Resource Recovery (CAPTURE), Frieda Saeysstraat 1, 9000 Ghent, Belgium
| | - Jesper Verleyen
- Center for Microbial Ecology and Technology (CMET), Ghent University, Coupure Links 653, 9000 Ghent, Belgium
| | - Benjamin Vanthuyne
- Center for Microbial Ecology and Technology (CMET), Ghent University, Coupure Links 653, 9000 Ghent, Belgium
| | - Ramon Ganigué
- Center for Microbial Ecology and Technology (CMET), Ghent University, Coupure Links 653, 9000 Ghent, Belgium; Center for Advanced Process Technology for Urban Resource Recovery (CAPTURE), Frieda Saeysstraat 1, 9000 Ghent, Belgium.
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10
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Hou Q, Wang Y, Cai W, Ni H, Zhao H, Zhang Z, Liu Z, Liu J, Zhong J, Guo Z. Metagenomic and physicochemical analyses reveal microbial community and functional differences between three types of low-temperature Daqu. Food Res Int 2022; 156:111167. [DOI: 10.1016/j.foodres.2022.111167] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2022] [Revised: 03/15/2022] [Accepted: 03/16/2022] [Indexed: 12/27/2022]
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11
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12
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Narisetty V, R. R, Maitra S, Tarafdar A, Alphy MP, Kumar AN, Madhavan A, Sirohi R, Awasthi MK, Sindhu R, Varjani S, Binod P. Waste-Derived Fuels and Renewable Chemicals for Bioeconomy Promotion: A Sustainable Approach. BIOENERGY RESEARCH 2022; 16:16-32. [PMID: 35350609 PMCID: PMC8947955 DOI: 10.1007/s12155-022-10428-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/31/2022] [Accepted: 02/28/2022] [Indexed: 06/14/2023]
Abstract
Bio-based fuels and chemicals through the biorefinery approach has gained significant interest as an alternative platform for the petroleum-derived processes as these biobased processes are noticed to have positive environmental and societal impacts. Decades of research was involved in understanding the diversity of microorganisms in different habitats that could synthesize various secondary metabolites that have functional potential as fuels, chemicals, nutraceuticals, food ingredients, and many more. Later, due to the substrate-related process economics, the diverse low-value, high-carbon feedstocks like lignocellulosic biomass, industrial byproducts, and waste streams were investigated to have greater potential. Among them, municipal solid wastes can be used as the source of substrates for the production of commercially viable gaseous and liquid fuels, as well as short-chain fattyacids and carboxylic acids. In this work, technologies and processes demanding the production of value-added products were explained in detail to understand and inculcate the value of municipal solid wastes and the economy, and it can provide to the biorefinery aspect.
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Affiliation(s)
- Vivek Narisetty
- Moolec Science, Innovation Centre, Gallows Hill, Warwick, CV34 6UW UK
| | - Reshmy R.
- Department of Science and Humanities, Providence College of Engineering, Chengannur, 689 122 Kerala India
| | - Shraddha Maitra
- Department of Agricultural and Biological Engineering, University of Illinois at Urbana-Champaign, Urbana, IL USA
| | - Ayon Tarafdar
- Livestock Production and Management Section, ICAR-Indian Veterinary Research Institute, Izatnagar, Bareilly, 243 122 Uttar Pradesh India
| | - Maria Paul Alphy
- Microbial Processes and Technology Division, CSIR-National Institute for Interdisciplinary Science and Technology (CSIR-NIIST), Trivandrum, 695 019 Kerala India
- Academy of Scientific and Innovative Research (AcSIR), Ghaziabad, 201 002 India
| | - A. Naresh Kumar
- Department of Environmental Science and Technology, University of Maryland, College Park, MD 20742 USA
| | - Aravind Madhavan
- Rajiv Gandhi Centre for Biotechnology, Jagathy, Trivandrum 695 014 India
| | - Ranjna Sirohi
- Department of Chemical and Biological Engineering, Korea University, 145, Anam-ro, 9 , Seongbuk-gu, Seoul 02841 South Korea
- Centre for Energy and Environmental Sustainabilty, Lucknow, 226001 Uttar Pradesh India
| | - Mukesh Kumar Awasthi
- College of Natural Resources and Environment, Northwest A & F University, Yangling, 712 100 Shaanxi China
| | - Raveendran Sindhu
- Department of Food Technology, T K M Institute of Technology, Kollam, 691 505 Kerala India
| | - Sunita Varjani
- Gujarat Pollution Control Board, Paryavaran Bhavan, CHH Road, Sector 10 A, Gandhinagar, 382010 Gujarat India
| | - Parameswaran Binod
- Microbial Processes and Technology Division, CSIR-National Institute for Interdisciplinary Science and Technology (CSIR-NIIST), Trivandrum, 695 019 Kerala India
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13
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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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14
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The Measurement, Application and Effect of Oxygen in Microbial Fermentations: Focusing on Methane and Carboxylate Production. FERMENTATION-BASEL 2022. [DOI: 10.3390/fermentation8040138] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Oxygen is considered detrimental to anaerobic fermentation processes by many practitioners. However, deliberate oxygen sparging has been used successfully for decades to remove H2S in anaerobic digestion (AD) systems. Moreover, microaeration techniques during AD have shown that small doses of oxygen may enhance process performance and promote the in situ degradation of recalcitrant compounds. However, existing oxygen dosing techniques are imprecise, which has led to inconsistent results between studies. At the same time, real-time oxygen fluxes cannot be reliably quantified due to the complexity of most bioreactor systems. Thus, there is a pressing need for robust monitoring and process control in applications where oxygen serves as an operating parameter or an experimental variable. This review summarizes and evaluates the available methodologies for oxygen measurement and dosing as they pertain to anaerobic microbiomes. The historical use of (micro-)aeration in anaerobic digestion and its potential role in other anaerobic fermentation processes are critiqued in detail. This critique also provides insights into the effects of oxygen on these microbiomes. Our assessment suggests that oxygen dosing, when implemented in a controlled and quantifiable manner, could serve as an effective tool for bioprocess engineers to further manipulate anaerobic microbiomes for either bioenergy or biochemical production.
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15
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Elhami V, Antunes EC, Temmink H, Schuur B. Recovery Techniques Enabling Circular Chemistry from Wastewater. Molecules 2022; 27:1389. [PMID: 35209179 PMCID: PMC8877087 DOI: 10.3390/molecules27041389] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2021] [Revised: 02/10/2022] [Accepted: 02/11/2022] [Indexed: 12/04/2022] Open
Abstract
In an era where it becomes less and less accepted to just send waste to landfills and release wastewater into the environment without treatment, numerous initiatives are pursued to facilitate chemical production from waste. This includes microbial conversions of waste in digesters, and with this type of approach, a variety of chemicals can be produced. Typical for digestion systems is that the products are present only in (very) dilute amounts. For such productions to be technically and economically interesting to pursue, it is of key importance that effective product recovery strategies are being developed. In this review, we focus on the recovery of biologically produced carboxylic acids, including volatile fatty acids (VFAs), medium-chain carboxylic acids (MCCAs), long-chain dicarboxylic acids (LCDAs) being directly produced by microorganisms, and indirectly produced unsaturated short-chain acids (USCA), as well as polymers. Key recovery techniques for carboxylic acids in solution include liquid-liquid extraction, adsorption, and membrane separations. The route toward USCA is discussed, including their production by thermal treatment of intracellular polyhydroxyalkanoates (PHA) polymers and the downstream separations. Polymers included in this review are extracellular polymeric substances (EPS). Strategies for fractionation of the different fractions of EPS are discussed, aiming at the valorization of both polysaccharides and proteins. It is concluded that several separation strategies have the potential to further develop the wastewater valorization chains.
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Affiliation(s)
- Vahideh Elhami
- Sustainable Process Technology Group, Process and Catalysis Cluster, Faculty of Science and Technology, University of Twente, Drienerlolaan 5, 7522 NB Enschede, The Netherlands; (V.E.); (E.C.A.)
| | - Evelyn C. Antunes
- Sustainable Process Technology Group, Process and Catalysis Cluster, Faculty of Science and Technology, University of Twente, Drienerlolaan 5, 7522 NB Enschede, The Netherlands; (V.E.); (E.C.A.)
- Wetsus—European Centre of Excellence for Sustainable Water Technology, Oostergoweg 9, 8911 MA Leeuwarden, The Netherlands;
| | - Hardy Temmink
- Wetsus—European Centre of Excellence for Sustainable Water Technology, Oostergoweg 9, 8911 MA Leeuwarden, The Netherlands;
- Department of Environmental Technology, Wageningen University, Bornse Weilanden 9, 6708 WG Wageningen, The Netherlands
| | - Boelo Schuur
- Sustainable Process Technology Group, Process and Catalysis Cluster, Faculty of Science and Technology, University of Twente, Drienerlolaan 5, 7522 NB Enschede, The Netherlands; (V.E.); (E.C.A.)
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16
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Wu SL, Wei W, Wang Y, Song L, Ni BJ. Transforming waste activated sludge into medium chain fatty acids in continuous two-stage anaerobic fermentation: Demonstration at different pH levels. CHEMOSPHERE 2022; 288:132474. [PMID: 34619255 DOI: 10.1016/j.chemosphere.2021.132474] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/12/2021] [Revised: 09/11/2021] [Accepted: 10/03/2021] [Indexed: 05/20/2023]
Abstract
Bioenergy recovery in the form of medium-chain fatty acids (MCFAs) from waste activated sludge (WAS) is increasingly attractive, which are valuable building blocks for fuel production. This study experimentally demonstrated the long-term MCFAs (C6-C8) production from WAS in two-stage anaerobic sludge fermentation at different pH conditions, using continuously operated bench-scale anaerobic reactors. The WAS was continuously converted to short chain fatty acids (SCFAs, 3500-3800 mg chemical oxygen demand (COD)/L) at the first stage via alkaline anaerobic fermentation, which was directly fed into the second stage as both substrates and inoculum for MCFAs production through chain elongation (CE). The productions of MCFAs at the second stage were continuously studied under three different pH conditions (i.e., 10, 7 and 5.5). The results demonstrated that there was no significant MCFAs production at pH 10 during the steady state, whereas the MCFAs productions were clearly observed at both pH 7 and pH 5.5, with much higher MCFAs production from WAS at pH 7 (i.e., 10.32 g COD/L MCFAs) than that at pH 5.5 (i.e., 8.73 g COD/L MCFAs) during the steady state. A higher MCFAs selectivity of 62.3% was also achieved at pH 7. The relatively lower MCFAs production and selectivity at pH 5.5 was likely due to the higher undissociated MCFAs generated at pH 5.5, which would pose toxicity impact on CE microbes and thus inhibit the CE process. Microbial community analysis confirmed that the relative abundances of CE related microbes (e.g., Clostridium sensu stricto 12 sp. and Clostridium sensu stricto 1) increased at pH 7 compared to those at pH 5.5, which enabled more efficient MCFAs production from WAS.
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Affiliation(s)
- Shu-Lin Wu
- State Key Laboratory of Pollution Control and Resources Reuse, College of Environmental Science and Engineering, Tongji University, Shanghai, 200092, PR China
| | - Wei Wei
- Centre for Technology in Water and Wastewater, School of Civil and Environmental Engineering, University of Technology Sydney, Sydney, NSW, 2007, Australia.
| | - Yun Wang
- State Key Laboratory of Pollution Control and Resources Reuse, College of Environmental Science and Engineering, Tongji University, Shanghai, 200092, PR China
| | - Lan Song
- School of Environmental Science and Engineering, Southern University of Science and Technology, Shenzhen, 518055, PR 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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Predicting the Presence and Abundance of Bacterial Taxa in Environmental Communities through Flow Cytometric Fingerprinting. mSystems 2021; 6:e0055121. [PMID: 34546074 PMCID: PMC8547484 DOI: 10.1128/msystems.00551-21] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
Microbiome management research and applications rely on temporally resolved measurements of community composition. Current technologies to assess community composition make use of either cultivation or sequencing of genomic material, which can become time-consuming and/or laborious in case high-throughput measurements are required. Here, using data from a shrimp hatchery as an economically relevant case study, we combined 16S rRNA gene amplicon sequencing and flow cytometry data to develop a computational workflow that allows the prediction of taxon abundances based on flow cytometry measurements. The first stage of our pipeline consists of a classifier to predict the presence or absence of the taxon of interest, with yielded an average accuracy of 88.13% ± 4.78% across the top 50 operational taxonomic units (OTUs) of our data set. In the second stage, this classifier was combined with a regression model to predict the relative abundances of the taxon of interest, which yielded an average R2 of 0.35 ± 0.24 across the top 50 OTUs of our data set. Application of the models to flow cytometry time series data showed that the generated models can predict the temporal dynamics of a large fraction of the investigated taxa. Using cell sorting, we validated that the model correctly associates taxa to regions in the cytometric fingerprint, where they are detected using 16S rRNA gene amplicon sequencing. Finally, we applied the approach of our pipeline to two other data sets of microbial ecosystems. This pipeline represents an addition to the expanding toolbox for flow cytometry-based monitoring of bacterial communities and complements the current plating- and marker gene-based methods. IMPORTANCE Monitoring of microbial community composition is crucial for both microbiome management research and applications. Existing technologies, such as plating and amplicon sequencing, can become laborious and expensive when high-throughput measurements are required. In recent years, flow cytometry-based measurements of community diversity have been shown to correlate well with those derived from 16S rRNA gene amplicon sequencing in several aquatic ecosystems, suggesting that there is a link between the taxonomic community composition and phenotypic properties as derived through flow cytometry. Here, we further integrated 16S rRNA gene amplicon sequencing and flow cytometry survey data in order to construct models that enable the prediction of both the presence and the abundances of individual bacterial taxa in mixed communities using flow cytometric fingerprinting. The developed pipeline holds great potential to be integrated into routine monitoring schemes and early warning systems for biotechnological applications.
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18
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Tang R, Luo H, Prommer H, Yue Z, Wang W, Su K, Hu ZH. Response of anaerobic granular sludge to long-term loading of roxarsone: From macro- to micro-scale perspective. WATER RESEARCH 2021; 204:117599. [PMID: 34481285 DOI: 10.1016/j.watres.2021.117599] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/25/2021] [Revised: 08/20/2021] [Accepted: 08/21/2021] [Indexed: 06/13/2023]
Abstract
Extensive use of organoarsenic feed additives such as roxarsone has caused organoarsenicals to occur in livestock wastewater and further within anaerobic wastewater treatment systems. Currently, information on the long-term impacts of roxarsone on anaerobic granular sludge (AGS) activity and the underlying mechanisms is very limited. In this study, the response of AGS to long-term loading of roxarsone was investigated using a laboratory up-flow anaerobic sludge blanket reactor spiked with 5.0 mg L-1 of roxarsone. Under the effect of roxarsone, methane production decreased by ∼40% due to the complete inhibition on acetoclastic methanogenic activity on day 260, before being restored eventually. Over 30% of the influent arsenic was accumulated in the AGS and the capability of AGS to prevent intracellular As(III) accumulation increased with time. The AGS size was reduced by ∼30% to 1.20‒1.26 mm. Based on morphology and confocal laser scanning microscopy analysis, roxarsone exposure stimulated the excretion of extracellular polymeric substances and the surface spalling of AGS. High-throughput sequencing analysis further indicated roxarsone initially altered the acidogenic pathway and severely inhibited the acetoclastic methanogen Methanothrix. Acetogenic bacteria and Methanothrix were finally enriched and became the main contributor for a full restoration of the initial methane production. These findings provide a deeper understanding on the effect of organoarsenicals on AGS, which is highly beneficial for the effective anaerobic treatment of organoarsenic-bearing wastewater.
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Affiliation(s)
- Rui Tang
- School of Civil Engineering, Hefei University of Technology, Hefei 230009, China; School of Resources and Environmental Engineering, Hefei University of Technology, Hefei 230009, China
| | - Haiping Luo
- Guangdong Provincial Key Laboratory of Environmental Pollution Control and Remediation Technology, School of Environmental Science and Engineering, Sun Yat-sen University, Guangzhou 510275, China
| | - Henning Prommer
- CSIRO Land and Water, Private Bag No. 5, Wembley, WA 6913, Australia; School of Earth Sciences, University of Western Australia, Crawley, WA 6009, Australia
| | - Zhengbo Yue
- School of Resources and Environmental Engineering, Hefei University of Technology, Hefei 230009, China
| | - Wei Wang
- School of Civil Engineering, Hefei University of Technology, Hefei 230009, China
| | - Kuizu Su
- School of Civil Engineering, Hefei University of Technology, Hefei 230009, China
| | - Zhen-Hu Hu
- School of Civil Engineering, Hefei University of Technology, Hefei 230009, China; Anhui Provincial Engineering Laboratory for Rural Water Environment and Resources, Hefei University of Technology, Hefei 230009, China.
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Baleeiro FCF, Ardila MS, Kleinsteuber S, Sträuber H. Effect of Oxygen Contamination on Propionate and Caproate Formation in Anaerobic Fermentation. Front Bioeng Biotechnol 2021; 9:725443. [PMID: 34568301 PMCID: PMC8460912 DOI: 10.3389/fbioe.2021.725443] [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: 06/15/2021] [Accepted: 08/19/2021] [Indexed: 01/19/2023] Open
Abstract
Mixed microbial cultures have become a preferred choice of biocatalyst for chain elongation systems due to their ability to convert complex substrates into medium-chain carboxylates. However, the complexity of the effects of process parameters on the microbial metabolic networks is a drawback that makes the task of optimizing product selectivity challenging. Here, we studied the effects of small air contaminations on the microbial community dynamics and the product formation in anaerobic bioreactors fed with lactate, acetate and H2/CO2. Two stirred tank reactors and two bubble column reactors were operated with H2/CO2 gas recirculation for 139 and 116 days, respectively, at pH 6.0 and 32°C with a hydraulic retention time of 14 days. One reactor of each type had periods with air contamination (between 97 ± 28 and 474 ± 33 mL O2 L−1 d−1, lasting from 4 to 32 days), while the control reactors were kept anoxic. During air contamination, production of n-caproate and CH4 was strongly inhibited, whereas no clear effect on n-butyrate production was observed. In a period with detectable O2 concentrations that went up to 18%, facultative anaerobes of the genus Rummeliibacillus became predominant and only n-butyrate was produced. However, at low air contamination rates and with O2 below the detection level, Coriobacteriia and Actinobacteria gained a competitive advantage over Clostridia and Methanobacteria, and propionate production rates increased to 0.8–1.8 mmol L−1 d−1 depending on the reactor (control reactors 0.1–0.8 mmol L−1 d−1). Moreover, i-butyrate production was observed, but only when Methanobacteria abundances were low and, consequently, H2 availability was high. After air contamination stopped completely, production of n-caproate and CH4 recovered, with n-caproate production rates of 1.4–1.8 mmol L−1 d−1 (control 0.7–2.1 mmol L−1 d−1). The results underline the importance of keeping strictly anaerobic conditions in fermenters when consistent n-caproate production is the goal. Beyond that, micro-aeration should be further tested as a controllable process parameter to shape the reactor microbiome. When odd-chain carboxylates are desired, further studies can develop strategies for their targeted production by applying micro-aerobic conditions.
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Affiliation(s)
- Flávio C F Baleeiro
- Department of Environmental Microbiology, Helmholtz Centre for Environmental Research - UFZ, Leipzig, Germany.,Institute of Process Engineering in Life Science 2, Technical Biology, Karlsruhe Institute of Technology - KIT, Karlsruhe, Germany
| | - Magda S Ardila
- Department of Environmental Microbiology, Helmholtz Centre for Environmental Research - UFZ, Leipzig, Germany.,Institute of Process Engineering in Life Science 2, Technical Biology, Karlsruhe Institute of Technology - KIT, Karlsruhe, Germany
| | - Sabine Kleinsteuber
- 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
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20
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Braune M, Yuan B, Sträuber H, McDowall SC, Nitzsche R, Gröngröft A. A Downstream Processing Cascade for Separation of Caproic and Caprylic Acid from Maize Silage-Based Fermentation Broth. Front Bioeng Biotechnol 2021; 9:725578. [PMID: 34527660 PMCID: PMC8436119 DOI: 10.3389/fbioe.2021.725578] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2021] [Accepted: 08/03/2021] [Indexed: 11/27/2022] Open
Abstract
Production of caproic and caprylic acid through anaerobic fermentation of crops or residual and waste biomass has been regarded as an alternative to the conventional ways, where plant oils and animal fats are mostly used. The downstream processing of the fermentation broth is a particular challenge since the broth has a highly complex composition and low concentrations of the target products. In this study, the proof-of-principle for a separation cascade for caproic (C6) and caprylic acid (C8) produced in a maize silage-based fermentation process was demonstrated. For clarification of the fermentation broth, a filter press and a ceramic ultrafiltration membrane was used to remove coarse solids and to separate suspended particles and macromolecules from the fermentation broth, respectively. With both techniques, the dry matter content was reduced from 6.8 to 2.3% and a particle-free product solution was obtained. Subsequently, the carboxylic acids were extracted with oleyl alcohol by liquid-liquid extraction with an extraction efficiency of 85% for C6 and 97% for C8. Over the whole cascade, 58% of caproic acid and 66% of caprylic acid were recovered from the fermentation broth into the extract. Among all separation steps, solid-liquid separation with the filter press caused the major part of the product loss of 21% of each carboxylic acid. By using separation equipment with a better solid separation efficiency such as decanter centrifuges or belt filter presses this loss could be minimized.
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Affiliation(s)
- Maria Braune
- Biorefineries Department, DBFZ Deutsches Biomasseforschungszentrum gemeinnützige GmbH, Leipzig, Germany
| | - Bomin Yuan
- Biorefineries Department, DBFZ Deutsches Biomasseforschungszentrum gemeinnützige GmbH, Leipzig, Germany
| | - Heike Sträuber
- Department of Environmental Microbiology, Helmholtz Centre for Environmental Research-UFZ, Leipzig, Germany
| | - Stewart Charles McDowall
- Biorefineries Department, DBFZ Deutsches Biomasseforschungszentrum gemeinnützige GmbH, Leipzig, Germany
| | - Roy Nitzsche
- Biorefineries Department, DBFZ Deutsches Biomasseforschungszentrum gemeinnützige GmbH, Leipzig, Germany
| | - Arne Gröngröft
- Biorefineries Department, DBFZ Deutsches Biomasseforschungszentrum gemeinnützige GmbH, Leipzig, Germany
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21
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Xu J, Bian B, Angenent LT, Saikaly PE. Long-Term Continuous Extraction of Medium-Chain Carboxylates by Pertraction With Submerged Hollow-Fiber Membranes. Front Bioeng Biotechnol 2021; 9:726946. [PMID: 34485261 PMCID: PMC8415110 DOI: 10.3389/fbioe.2021.726946] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2021] [Accepted: 07/28/2021] [Indexed: 11/13/2022] Open
Abstract
Medium-chain carboxylic acids (MCCAs), which can be generated from organic waste and agro-industrial side streams through microbial chain elongation, are valuable chemicals with numerous industrial applications. Membrane-based liquid-liquid extraction (pertraction) as a downstream separation process to extract MCCAs has been applied successfully. Here, a novel pertraction system with submerged hollow-fiber membranes in the fermentation bioreactor was applied to increase the MCCA extraction rate and reduce the footprint. The highest average surface-corrected MCCA extraction rate of 655.2 ± 86.4 mmol C m−2 d−1 was obtained, which was higher than any other previous reports, albeit the relatively small surface area removed only 11.6% of the introduced carbon via pertraction. This submerged extraction system was able to continuously extract MCCAs with a high extraction rate for more than 8 months. The average extraction rate of MCCA by internal membrane was 3.0- to 4.7-fold higher than the external pertraction (traditional pertraction) in the same bioreactor. A broth upflow velocity of 7.6 m h−1 was more efficient to extract MCCAs when compared to periodic biogas recirculation operation as a means to prevent membrane fouling. An even higher broth upflow velocity of 40.5 m h−1 resulted in a significant increase in methane production, losing more than 30% of carbon conversion to methane due to a loss of H2, and a subsequent drop in the H2 partial pressure. This resulted in the shift from a microbial community with chain elongators as the key functional group to methanogens, because the drop in H2 partial pressure led to thermodynamic conditions that oxidizes ethanol and carboxylic acids to acetate and H2 with methanogens as the syntrophic partner. Thus, operators of chain elongating systems should monitor the H2 partial pressure when changes in operating conditions are made.
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Affiliation(s)
- Jiajie Xu
- Biological and Environmental Science and Engineering (BESE) Division, Water Desalination and Reuse Center (WDRC), King Abdullah University of Science and Technology, Thuwal, Saudi Arabia
| | - Bin Bian
- Biological and Environmental Science and Engineering (BESE) Division, Water Desalination and Reuse Center (WDRC), King Abdullah University of Science and Technology, Thuwal, Saudi Arabia
| | - Largus T Angenent
- Environmental Biotechnology Group, Center for Applied Geosciences, University of Tübingen, Tübingen, Germany
| | - Pascal E Saikaly
- Biological and Environmental Science and Engineering (BESE) Division, Water Desalination and Reuse Center (WDRC), King Abdullah University of Science and Technology, Thuwal, Saudi Arabia
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22
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Ingle AT, Fortney NW, Walters KA, Donohue TJ, Noguera DR. Mixed Acid Fermentation of Carbohydrate-Rich Dairy Manure Hydrolysate. Front Bioeng Biotechnol 2021; 9:724304. [PMID: 34414173 PMCID: PMC8370043 DOI: 10.3389/fbioe.2021.724304] [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: 06/12/2021] [Accepted: 07/20/2021] [Indexed: 01/04/2023] Open
Abstract
Dairy manure (DM) is an abundant agricultural residue that is largely composed of lignocellulosic biomass. The aim of this study was to investigate if carbon derived from DM fibers can be recovered as medium-chain fatty acids (MCFAs), which are mixed culture fermentation products of economic interest. DM fibers were subjected to combinations of physical, enzymatic, chemical, and thermochemical pretreatments to evaluate the possibility of producing carbohydrate-rich hydrolysates suitable for microbial fermentation by mixed cultures. Among the pretreatments tested, decrystalization dilute acid pretreatment (DCDA) produced the highest concentrations of glucose and xylose, and was selected for further experiments. Bioreactors fed DCDA hydrolysate were operated. Acetic acid and butyric acid comprised the majority of end products during operation of the bioreactors. MCFAs were transiently produced at a maximum concentration of 0.17 mg CODMCFAs/mg CODTotal. Analyses of the microbial communities in the bioreactors suggest that lactic acid bacteria, Megasphaera, and Caproiciproducens were involved in MCFA and C4 production during DCDA hydrolysate metabolism.
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Affiliation(s)
- Abel T Ingle
- Department of Civil and Environmental Engineering, University of Wisconsin-Madison, Madison, WI, United States
| | - Nathaniel W Fortney
- Wisconsin Energy Institute, University of Wisconsin-Madison, Madison, WI, United States.,Great Lakes Bioenergy Research Center, Madison, WI, United States
| | - Kevin A Walters
- Wisconsin Energy Institute, University of Wisconsin-Madison, Madison, WI, United States.,Great Lakes Bioenergy Research Center, Madison, WI, United States.,Department of Bacteriology, University of Wisconsin-Madison, Madison, WI, United States
| | - Timothy J Donohue
- Wisconsin Energy Institute, University of Wisconsin-Madison, Madison, WI, United States.,Great Lakes Bioenergy Research Center, Madison, WI, United States.,Department of Bacteriology, University of Wisconsin-Madison, Madison, WI, United States
| | - Daniel R Noguera
- Department of Civil and Environmental Engineering, University of Wisconsin-Madison, Madison, WI, United States.,Wisconsin Energy Institute, University of Wisconsin-Madison, Madison, WI, United States.,Great Lakes Bioenergy Research Center, Madison, WI, United States
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23
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Potential Valorization of Organic Waste Streams to Valuable Organic Acids through Microbial Conversion: A South African Case Study. Catalysts 2021. [DOI: 10.3390/catal11080964] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
The notion of a “biobased economy” in the context of a developing country such as South Africa (SA) necessitates the development of technologies that utilize sustainable feedstocks, have simple and robust operations, are feasible at small scale and produce a variety of valuable bioproducts, thus fitting the biorefinery concept. This case study focuses on the microbial production of higher-value products from selected organic waste streams abundant in the South African agricultural sector using microbes adapted to utilize different parts of biomass waste streams. A ruminant-based carboxylate platform based on mixed or undefined anaerobic co-cultures of rumen microorganisms can convert the carbohydrate polymers in the lignocellulosic part of organic waste streams to carboxylic acids that can be upgraded to biofuels or green chemicals. Furthermore, yeast and fungi can convert the simpler carbohydrates (such as the sugars and malic acid in grape and apple pomace) to ethanol and high-value carboxylic acids, such as lactic, fumaric, succinic and citric acid. This review will discuss the combinational use of the ruminal carboxylate platform and native or recombinant yeasts to valorize biomass waste streams through the production of higher-value organic acids with various applications.
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24
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Fortney NW, Hanson NJ, Rosa PRF, Donohue TJ, Noguera DR. Diverse Profile of Fermentation Byproducts From Thin Stillage. Front Bioeng Biotechnol 2021; 9:695306. [PMID: 34336807 PMCID: PMC8320890 DOI: 10.3389/fbioe.2021.695306] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2021] [Accepted: 06/02/2021] [Indexed: 12/25/2022] Open
Abstract
The economy of biorefineries is influenced not only by biofuel production from carbohydrates but also by the production of valuable compounds from largely underutilized industrial residues. Currently, the demand for many chemicals that could be made in a biorefinery, such as succinic acid (SA), medium-chain fatty acids (MCFAs), and lactic acid (LA), is fulfilled using petroleum, palm oil, or pure carbohydrates as raw materials, respectively. Thin stillage (TS), the residual liquid material following distillation of ethanol, is an underutilized coproduct from the starch biofuel industry. This carbon-rich material has the potential for chemical upgrading by microorganisms. Here, we explored the formation of different fermentation products by microbial communities grown on TS using different bioreactor conditions. At the baseline operational condition (6-day retention time, pH 5.5, 35°C), we observed a mixture of MCFAs as the principal fermentation products. Operation of a bioreactor with a 1-day retention time induced an increase in SA production, and a temperature increase to 55°C resulted in the accumulation of lactic and propionic acids. In addition, a reactor operated with a 1-day retention time at 55°C conditions resulted in LA accumulation as the main fermentation product. The prominent members of the microbial community in each reactor were assessed by 16S rRNA gene amplicon sequencing and phylogenetic analysis. Under all operating conditions, members of the Lactobacillaceae family within Firmicutes and the Acetobacteraceae family within Proteobacteria were ubiquitous. Members of the Prevotellaceae family within Bacteroidetes and Lachnospiraceae family within the Clostridiales order of Firmicutes were mostly abundant at 35°C and not abundant in the microbial communities of the TS reactors incubated at 55°C. The ability to adjust bioreactor operating conditions to select for microbial communities with different fermentation product profiles offers new strategies to explore and compare potentially valuable fermentation products from TS and allows industries the flexibility to adapt and switch chemical production based on market prices and demands.
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Affiliation(s)
- Nathaniel W Fortney
- Great Lakes Bioenergy Research Center, University of Wisconsin-Madison, Madison, WI, United States
| | - Nathaniel J Hanson
- Great Lakes Bioenergy Research Center, University of Wisconsin-Madison, Madison, WI, United States.,Wisconsin Youth Apprenticeship Program, Department of Workforce Development, Madison, WI, United States
| | - Paula R F Rosa
- Great Lakes Bioenergy Research Center, University of Wisconsin-Madison, Madison, WI, United States.,Department of Chemical Engineering, Federal University of São Carlos, São Carlos, Brazil
| | - Timothy J Donohue
- Great Lakes Bioenergy Research Center, University of Wisconsin-Madison, Madison, WI, United States.,Department of Bacteriology, University of Wisconsin-Madison, Madison, WI, United States
| | - Daniel R Noguera
- Great Lakes Bioenergy Research Center, University of Wisconsin-Madison, Madison, WI, United States.,Department of Civil and Environmental Engineering, University of Wisconsin-Madison, Madison, WI, United States
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25
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De Groof V, Coma M, Arnot T, Leak DJ, Lanham AB. Selecting fermentation products for food waste valorisation with HRT and OLR as the key operational parameters. WASTE MANAGEMENT (NEW YORK, N.Y.) 2021; 127:80-89. [PMID: 33932853 DOI: 10.1016/j.wasman.2021.04.023] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/18/2020] [Revised: 03/29/2021] [Accepted: 04/10/2021] [Indexed: 06/12/2023]
Abstract
Acidogenic fermentation is attractive for food waste valorisation. A better understanding is required on how operation affects product selectivity. This study demonstrated that the hydraulic retention time (HRT) and organic loading rate (OLR) selected fermentation pathways in a single-stage, semi-continuous stirred tank reactor. Three combinations of HRT and OLR were tested to distinguish the effect of each parameter. Three fermentation profiles with distinct microbial communities were obtained. Predominantly n-butyric acid (13 ± 2 gCOD L-1, 55 ± 14% of carboxylates) was produced at an HRT of 8.5 days and OLR around 12 gCOD L-1d-1. Operating at an HRT two days longer, yet with similar OLR, stimulated chain elongation (up to 13.6 gCOD L-1 of n-caproic acid). This was reflected by a microbial community twice as diverse at longer HRT as indicated by first and second order Hill number (1D = 24 ± 4, 2D = 12 ± 3) and by a higher relative abundance of genera related to secondary fermentation, such as the VFA-elongating Caproiciproducens spp., and secondary lactic acid fermenter Secundilactobacillus spp.. Operating at a higher OLR (20 gCOD L-1d-1) but HRT of 8.5 days, resulted in typical lactic acid fermentation (34 ± 5 gCOD L-1) harbouring a less diverse community (1D = 8.0 ± 0.7, 2D = 5.7 ± 0.9) rich in acid-resistant homofermentative Lactobacillus spp. These findings demonstrate that a flexible product portfolio can be achieved by small adjustments in two key operating conditions. This improves the economic potential of acidogenic fermentation for food waste valorisation.
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Affiliation(s)
- Vicky De Groof
- EPSRC Centre for Doctoral Training in Sustainable Chemical Technologies, University of Bath, Claverton Down, Bath BA2 7AY, UK; Department of Chemical Engineering, University of Bath, Claverton Down, Bath BA2 7AY, UK
| | - Marta Coma
- Centre for Sustainable and Circular Technologies (CSCT), University of Bath, Claverton Down, Bath BA2 7AY, UK
| | - Tom Arnot
- Department of Chemical Engineering, University of Bath, Claverton Down, Bath BA2 7AY, UK; Centre for Sustainable and Circular Technologies (CSCT), University of Bath, Claverton Down, Bath BA2 7AY, UK; Water Innovation & Research Centre (WIRC), University of Bath, Claverton Down, Bath BA2 7AY, UK
| | - David J Leak
- Centre for Sustainable and Circular Technologies (CSCT), University of Bath, Claverton Down, Bath BA2 7AY, UK; Water Innovation & Research Centre (WIRC), University of Bath, Claverton Down, Bath BA2 7AY, UK; Department of Biology & Biochemistry, University of Bath, Claverton Down, Bath BA2 7AY, UK
| | - Ana B Lanham
- Department of Chemical Engineering, University of Bath, Claverton Down, Bath BA2 7AY, UK; Water Innovation & Research Centre (WIRC), University of Bath, Claverton Down, Bath BA2 7AY, UK.
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26
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Microbial Ecological Mechanism for Long-Term Production of High Concentrations of n-Caproate via Lactate-Driven Chain Elongation. Appl Environ Microbiol 2021; 87:AEM.03075-20. [PMID: 33741616 DOI: 10.1128/aem.03075-20] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2020] [Accepted: 03/10/2021] [Indexed: 12/11/2022] Open
Abstract
Lactate-driven chain elongation (LCE) has emerged as a new biotechnology to upgrade organic waste streams into a valuable biochemical and fuel precursor, medium-chain carboxylate, n-caproate. Considering that a low cost of downstream extraction is critical for biorefinery technology, a high concentration of n-caproate production is very important to improve the scale-up of the LCE process. We report here that in a nonsterile open environment, the n-caproate concentration was increased from the previous record of 25.7 g·liter-1 to a new high level of 33.7 g·liter-1 (76.8 g chemical oxygen demand [COD]·liter - 1), with the highest production rate being 11.5 g·liter-1·day-1 (26.2 g COD·liter - 1·day-1). In addition, the LCE process remained stable, with an average concentration of n-caproate production of 20.2 ± 5.62 g·liter-1 (46.1 ± 12.8 g COD·liter - 1) for 780 days. Dynamic changes in taxonomic composition integrated with metagenomic data reveal the microbial ecology for long-term production of high concentrations of n-caproate: (i) the core microbiome is related to efficient functional groups, such as Ruminococcaceae (with functional strain CPB6); (ii) the core bacteria can maintain stability for long-term operation; (iii) the microbial network has relatively low microbe-microbe interaction strength; and (iv) low relative abundance and variety of competitors. The network structure could be shaped by hydraulic retention time (HRT) over time, and long-term operation at an HRT of 8 days displayed higher efficacy.IMPORTANCE Our research revealed the microbial network of the LCE reactor microbiome for n-caproate production at high concentrations, which will provide a foundation for designing or engineering the LCE reactor microbiome to recover n-caproate from organic waste streams in the future. In addition, the hypothetical model of the reactor microbiome that we proposed may offer guidance for researchers to find the underlying microbial mechanism when they encounter low-efficiency n-caproate production from the LCE process. We anticipate that our research will rapidly advance LCE biotechnology with the goal of promoting the sustainable development of human society.
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27
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Gu Y, Zhu X, Lin F, Shen C, Li Y, Ao L, Fan W, Ren C, Xu Y. Caproicibacterium amylolyticum gen. nov., sp. nov., a novel member of the family Oscillospiraceae isolated from pit clay used for making Chinese strong aroma-type liquor. Int J Syst Evol Microbiol 2021; 71. [PMID: 33906707 DOI: 10.1099/ijsem.0.004789] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
An anaerobic, Gram-stain-positive, rod-shaped, motile and spore-forming bacterium, designated strain LBM18003T, was isolated from pit clay used for making Chinese strong aroma-type liquor. Growth occurred at 20-40 °C (optimum, 30-37 °C), pH 4.5-9.5 (optimum, pH 6.5-7.0) and in the presence of 0.0-1.0 % (w/v) sodium chloride (optimum, 0 %). The predominant fatty acids were C16:0, C14:0, C14:0 DMA and C16:0 3-OH, and the major polar lipids were diphosphatidylglycerol, phosphatidylglycerol, two unidentified phospholipids and nine unidentified glycolipids. Phylogenetic analysis revealed that strain LBM18003T is a novel member of the family Oscillospiraceae. The 16S rRNA gene sequence similarities of strain LBM18003T to its two most closely related species were less than 94.5 % for distinguishing genera, i.e. closely related to Caproiciproducens galactitolivorans JCM 30532T (94.1 %) and Caproicibacter fermentans DSM 107079T (93.2 %). The genome size of strain LBM18003T was 2 996 201 bp and its DNA G+C content was 48.48 mol%. Strain LBM18003T exhibited 67.8 and 68.1% pairwise-determined whole-genome average nucleotide identity values to Caproiciproducens galactitolivorans JCM 30532T and Caproicibacter fermentans DSM 107079T, respectively; and showed 62.2 and 61.0 % the average amino acid identity values to Caproiciproducens galactitolivorans JCM 30532T and Caproicibacter fermentans DSM 107079T, respectively; and demonstrated 46.1 and 41.5 % conserved genes to Caproiciproducens galactitolivorans JCM 30532T and Caproicibacter fermentans DSM 107079T, respectively. The comparisons of 16S rRNA gene and genome sequences confirmed that strain LBM18003T represented a novel genus of the family Oscillospiraceae. Based on morphological, physiological, biochemical, chemotaxonomic, genotypic and phylogenetic results, strain LBM18003T represents a novel species of a novel genus of the family Oscillospiraceae, for which the name Caproicibacterium amylolyticum gen. nov., sp. nov. is proposed. The type strain is LBM18003T (=GDMCC 1.1626T=JCM 33783T).
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Affiliation(s)
- Yang Gu
- Key Laboratory of Industrial Biotechnology of Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi 214122, PR China
| | - Xiaojun Zhu
- Key Laboratory of Industrial Biotechnology of Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi 214122, PR China
| | - Feng Lin
- National Engineering Research Center of Solid-state Brewing, Luzhou 646000, PR China
| | - Caihong Shen
- National Engineering Research Center of Solid-state Brewing, Luzhou 646000, PR China
| | - Yong Li
- National Engineering Research Center of Solid-state Brewing, Luzhou 646000, PR China
| | - Ling Ao
- National Engineering Research Center of Solid-state Brewing, Luzhou 646000, PR China
| | - Wenlai Fan
- Key Laboratory of Industrial Biotechnology of Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi 214122, PR China
| | - Cong Ren
- Key Laboratory of Industrial Biotechnology of Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi 214122, PR China
| | - Yan Xu
- Key Laboratory of Industrial Biotechnology of Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi 214122, PR China
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28
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El-Far M, Durand M, Turcotte I, Larouche-Anctil E, Sylla M, Zaidan S, Chartrand-Lefebvre C, Bunet R, Ramani H, Sadouni M, Boldeanu I, Chamberland A, Lesage S, Baril JG, Trottier B, Thomas R, Gonzalez E, Filali-Mouhim A, Goulet JP, Martinson JA, Kassaye S, Karim R, Kizer JR, French AL, Gange SJ, Ancuta P, Routy JP, Hanna DB, Kaplan RC, Chomont N, Landay AL, Tremblay CL. Upregulated IL-32 Expression And Reduced Gut Short Chain Fatty Acid Caproic Acid in People Living With HIV With Subclinical Atherosclerosis. Front Immunol 2021; 12:664371. [PMID: 33936102 PMCID: PMC8083984 DOI: 10.3389/fimmu.2021.664371] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2021] [Accepted: 03/26/2021] [Indexed: 12/22/2022] Open
Abstract
Despite the success of antiretroviral therapy (ART), people living with HIV (PLWH) are still at higher risk for cardiovascular diseases (CVDs) that are mediated by chronic inflammation. Identification of novel inflammatory mediators with the inherent potential to be used as CVD biomarkers and also as therapeutic targets is critically needed for better risk stratification and disease management in PLWH. Here, we investigated the expression and potential role of the multi-isoform proinflammatory cytokine IL-32 in subclinical atherosclerosis in PLWH (n=49 with subclinical atherosclerosis and n=30 without) and HIV- controls (n=25 with subclinical atherosclerosis and n=24 without). While expression of all tested IL-32 isoforms (α, β, γ, D, ϵ, and θ) was significantly higher in peripheral blood from PLWH compared to HIV- controls, IL-32D and IL-32θ isoforms were further upregulated in HIV+ individuals with coronary artery atherosclerosis compared to their counterparts without. Upregulation of these two isoforms was associated with increased plasma levels of IL-18 and IL-1β and downregulation of the atheroprotective protein TRAIL, which together composed a unique atherosclerotic inflammatory signature specific for PLWH compared to HIV- controls. Logistic regression analysis demonstrated that modulation of these inflammatory variables was independent of age, smoking, and statin treatment. Furthermore, our in vitro functional data linked IL-32 to macrophage activation and production of IL-18 and downregulation of TRAIL, a mechanism previously shown to be associated with impaired cholesterol metabolism and atherosclerosis. Finally, increased expression of IL-32 isoforms in PLWH with subclinical atherosclerosis was associated with altered gut microbiome (increased pathogenic bacteria; Rothia and Eggerthella species) and lower abundance of the gut metabolite short-chain fatty acid (SCFA) caproic acid, measured in fecal samples from the study participants. Importantly, caproic acid diminished the production of IL-32, IL-18, and IL-1β in human PBMCs in response to bacterial LPS stimulation. In conclusion, our studies identified an HIV-specific atherosclerotic inflammatory signature including specific IL-32 isoforms, which is regulated by the SCFA caproic acid and that may lead to new potential therapies to prevent CVD in ART-treated PLWH.
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Affiliation(s)
- Mohamed El-Far
- University of Montreal Hospital Centre (CRCHUM)-Research Centre, Montréal, QC, Canada
| | - Madeleine Durand
- University of Montreal Hospital Centre (CRCHUM)-Research Centre, Montréal, QC, Canada.,Département de Microbiologie, Infectiologie et Immunologie, Faculté de Médecine, Université de Montréal, Montréal, QC, Canada
| | - Isabelle Turcotte
- University of Montreal Hospital Centre (CRCHUM)-Research Centre, Montréal, QC, Canada.,Département de Microbiologie, Infectiologie et Immunologie, Faculté de Médecine, Université de Montréal, Montréal, QC, Canada
| | | | - Mohamed Sylla
- University of Montreal Hospital Centre (CRCHUM)-Research Centre, Montréal, QC, Canada
| | - Sarah Zaidan
- University of Montreal Hospital Centre (CRCHUM)-Research Centre, Montréal, QC, Canada.,Département de Microbiologie, Infectiologie et Immunologie, Faculté de Médecine, Université de Montréal, Montréal, QC, Canada
| | - Carl Chartrand-Lefebvre
- University of Montreal Hospital Centre (CRCHUM)-Research Centre, Montréal, QC, Canada.,Département de Radiologie, Radio-oncologie et Médecine Nucléaire, Faculté de Médecine, Université de Montréal, Montréal, QC, Canada
| | - Rémi Bunet
- University of Montreal Hospital Centre (CRCHUM)-Research Centre, Montréal, QC, Canada.,Département de Microbiologie, Infectiologie et Immunologie, Faculté de Médecine, Université de Montréal, Montréal, QC, Canada
| | - Hardik Ramani
- University of Montreal Hospital Centre (CRCHUM)-Research Centre, Montréal, QC, Canada.,Département de Microbiologie, Infectiologie et Immunologie, Faculté de Médecine, Université de Montréal, Montréal, QC, Canada
| | - Manel Sadouni
- University of Montreal Hospital Centre (CRCHUM)-Research Centre, Montréal, QC, Canada
| | - Irina Boldeanu
- University of Montreal Hospital Centre (CRCHUM)-Research Centre, Montréal, QC, Canada
| | - Annie Chamberland
- University of Montreal Hospital Centre (CRCHUM)-Research Centre, Montréal, QC, Canada
| | - Sylvie Lesage
- Département de Microbiologie, Infectiologie et Immunologie, Faculté de Médecine, Université de Montréal, Montréal, QC, Canada.,Hôpital Maisonneuve-Rosemont, Montréal, QC, Canada
| | - Jean-Guy Baril
- Centre de médecine urbaine du Quartier latin, Montréal, QC, Canada
| | - Benoit Trottier
- Centre de médecine urbaine du Quartier latin, Montréal, QC, Canada
| | | | - Emmanuel Gonzalez
- Department of Human Genetics, Canadian Centre for Computational Genomics, McGill University, Montreal, QC, Canada.,Microbiome Platform Research, McGill Interdisciplinary Initiative in Infection and Immunity, McGill University, Montreal, QC, Canada
| | - Ali Filali-Mouhim
- University of Montreal Hospital Centre (CRCHUM)-Research Centre, Montréal, QC, Canada
| | | | - Jeffrey A Martinson
- Department of Internal Medicine, Rush University Medical Center, Chicago, IL, United States
| | - Seble Kassaye
- Department of Medicine, Georgetown University, Washington, DC, United States
| | - Roksana Karim
- Department of Preventive Medicine, University of Southern California, Los Angeles, CA, United States
| | - Jorge R Kizer
- Cardiology Section, San Francisco Veterans Affairs Health Care System, San Francisco, CA, United States.,Departments of Medicine, Epidemiology and Biostatistics, University of California San Francisco, San Francisco, CA, United States
| | - Audrey L French
- Division of Infectious Diseases, Stroger Hospital of Cook County, Chicago IL, United States
| | - Stephen J Gange
- Department of Epidemiology, Bloomberg School of Public Health, Johns Hopkins University, Baltimore, MD, United States
| | - Petronela Ancuta
- University of Montreal Hospital Centre (CRCHUM)-Research Centre, Montréal, QC, Canada.,Département de Microbiologie, Infectiologie et Immunologie, Faculté de Médecine, Université de Montréal, Montréal, QC, Canada
| | - Jean-Pierre Routy
- Research Institute of McGill University Health Centre, Montréal, QC, Canada
| | - David B Hanna
- Department of Epidemiology and Population Health, Albert Einstein College of Medicine, Bronx, NY, United States
| | - Robert C Kaplan
- Department of Epidemiology and Population Health, Albert Einstein College of Medicine, Bronx, NY, United States.,Divsion of Public Health Sciences, Fred Hutchinson Cancer Research Center, Seattle, WA, United States
| | - Nicolas Chomont
- University of Montreal Hospital Centre (CRCHUM)-Research Centre, Montréal, QC, Canada.,Département de Microbiologie, Infectiologie et Immunologie, Faculté de Médecine, Université de Montréal, Montréal, QC, Canada
| | - Alan L Landay
- Department of Internal Medicine, Rush University Medical Center, Chicago, IL, United States
| | - Cécile L Tremblay
- University of Montreal Hospital Centre (CRCHUM)-Research Centre, Montréal, QC, Canada.,Département de Microbiologie, Infectiologie et Immunologie, Faculté de Médecine, Université de Montréal, Montréal, QC, Canada
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29
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Baleeiro FCF, Kleinsteuber S, Sträuber H. Hydrogen as a Co-electron Donor for Chain Elongation With Complex Communities. Front Bioeng Biotechnol 2021; 9:650631. [PMID: 33898406 PMCID: PMC8059637 DOI: 10.3389/fbioe.2021.650631] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2021] [Accepted: 03/12/2021] [Indexed: 01/04/2023] Open
Abstract
Electron donor scarcity is seen as one of the major issues limiting economic production of medium-chain carboxylates from waste streams. Previous studies suggest that co-fermentation of hydrogen in microbial communities that realize chain elongation relieves this limitation. To better understand how hydrogen co-feeding can support chain elongation, we enriched three different microbial communities from anaerobic reactors (A, B, and C with ascending levels of diversity) for their ability to produce medium-chain carboxylates from conventional electron donors (lactate or ethanol) or from hydrogen. In the presence of abundant acetate and CO2, the effects of different abiotic parameters (pH values in acidic to neutral range, initial acetate concentration, and presence of chemical methanogenesis inhibitors) were tested along with the enrichment. The presence of hydrogen facilitated production of butyrate by all communities and improved production of i-butyrate and caproate by the two most diverse communities (B and C), accompanied by consumption of acetate, hydrogen, and lactate/ethanol (when available). Under optimal conditions, hydrogen increased the selectivity of conventional electron donors to caproate from 0.23 ± 0.01 mol e-/mol e- to 0.67 ± 0.15 mol e-/mol e- with a peak caproate concentration of 4.0 g L-1. As a trade-off, the best-performing communities also showed hydrogenotrophic methanogenesis activity by Methanobacterium even at high concentrations of undissociated acetic acid of 2.9 g L-1 and at low pH of 4.8. According to 16S rRNA amplicon sequencing, the suspected caproate producers were assigned to the family Anaerovoracaceae (Peptostreptococcales) and the genera Megasphaera (99.8% similarity to M. elsdenii), Caproiciproducens, and Clostridium sensu stricto 12 (97-100% similarity to C. luticellarii). Non-methanogenic hydrogen consumption correlated to the abundance of Clostridium sensu stricto 12 taxa (p < 0.01). If a robust methanogenesis inhibition strategy can be found, hydrogen co-feeding along with conventional electron donors can greatly improve selectivity to caproate in complex communities. The lessons learned can help design continuous hydrogen-aided chain elongation bioprocesses.
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Affiliation(s)
- Flávio C F Baleeiro
- Department of Environmental Microbiology, Helmholtz Centre for Environmental Research - UFZ, Leipzig, Germany.,Technical Biology, Institute of Process Engineering in Life Science II, Karlsruhe Institute of Technology - KIT, Karlsruhe, Germany
| | - Sabine Kleinsteuber
- 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
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30
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Rico JL, Reardon KF, De Long SK. Inoculum microbiome composition impacts fatty acid product profile from cellulosic feedstock. BIORESOURCE TECHNOLOGY 2021; 323:124532. [PMID: 33422791 DOI: 10.1016/j.biortech.2020.124532] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/17/2020] [Revised: 12/07/2020] [Accepted: 12/08/2020] [Indexed: 06/12/2023]
Abstract
Conversion of organic wastes to fatty acids rather than methane through anaerobic digestion-based technologies has considerable promise. However, the relationships between microbiome structure and fatty acids produced from cellulosic feedstocks are not well understood. This study investigated the nature of those relationships for anaerobic digester sludge, bison rumen, and cattle rumen inocula grown on cellulose. Acetic acid production was highest in anaerobic sludge reactors, while propionic acid production was highest in cattle rumen reactors. Butyric and pentanoic acid were produced at the highest rates in bison rumen before Day 5. Reactor microbiomes remained distinct, despite identical operating conditions. Novel associations linked Alistipes with butyric acid production and Eubacterium nodatum and Clostridiales bacterium with pentanoic acid production. This study provides new insights into the ability of microbiomes to convert cellulose to different fatty acid mixtures and adds impetus for the rewiring of anaerobic digestion to generate high-value products.
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Affiliation(s)
- Jorge L Rico
- Department of Civil and Environmental Engineering, Colorado State University, 1301 Campus Delivery, Fort Collins, CO 80523, USA.
| | - Kenneth F Reardon
- Department of Chemical and Biological Engineering, Colorado State University, 1301 Campus Delivery, Fort Collins, CO 80523, USA.
| | - Susan K De Long
- Department of Civil and Environmental Engineering, Colorado State University, 1301 Campus Delivery, Fort Collins, CO 80523, USA.
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Candry P, Ganigué R. Chain elongators, friends, and foes. Curr Opin Biotechnol 2021; 67:99-110. [PMID: 33529974 DOI: 10.1016/j.copbio.2021.01.005] [Citation(s) in RCA: 33] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2020] [Revised: 01/02/2021] [Accepted: 01/07/2021] [Indexed: 12/14/2022]
Abstract
Bioproduction of medium chain carboxylic acids has recently emerged as an alternative strategy to valorize low-value organic waste and side-streams. Key to this route is chain elongation, an anaerobic microbial process driven by ethanol, lactic acid, or carbohydrates. Because these technologies use wastes as feedstocks, mixed microbial communities are often considered as biocatalysts. Understanding and steering these microbiomes is key to optimize bioprocess performance. From a meta-analysis of publicly available sequencing data, we (i) explore how the current collection of isolated chain elongators compares to microbiome members, (ii) discuss the main beneficial and antagonistic interactions with community partners, and (iii) identify the key research gaps and needs to help understand chain elongation microbiomes, and design/steer these novel bioproduction processes.
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Affiliation(s)
- Pieter Candry
- Civil and Environmental Engineering, University of Washington, 201 More Hall, Box 352700, Seattle, WA 98195-2700, USA
| | - Ramon Ganigué
- Center for Microbial Ecology and Technology (CMET), Ghent University, Coupure Links 653, 9000 Ghent, Belgium.
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Liu B, Popp D, Müller N, Sträuber H, Harms H, Kleinsteuber S. Three Novel Clostridia Isolates Produce n-Caproate and iso-Butyrate from Lactate: Comparative Genomics of Chain-Elongating Bacteria. Microorganisms 2020; 8:microorganisms8121970. [PMID: 33322390 PMCID: PMC7764203 DOI: 10.3390/microorganisms8121970] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2020] [Revised: 12/08/2020] [Accepted: 12/09/2020] [Indexed: 02/07/2023] Open
Abstract
The platform chemicals n-caproate and iso-butyrate can be produced by anaerobic fermentation from agro-industrial residues in a process known as microbial chain elongation. Few lactate-consuming chain-elongating species have been isolated and knowledge on their shared genetic features is still limited. Recently we isolated three novel clostridial strains (BL-3, BL-4, and BL-6) that convert lactate to n-caproate and iso-butyrate. Here, we analyzed the genetic background of lactate-based chain elongation in these isolates and other chain-elongating species by comparative genomics. The three strains produced n-caproate, n-butyrate, iso-butyrate, and acetate from lactate, with the highest proportions of n-caproate (18%) for BL-6 and of iso-butyrate (23%) for BL-4 in batch cultivation at pH 5.5. They show high genomic heterogeneity and a relatively small core-genome size. The genomes contain highly conserved genes involved in lactate oxidation, reverse β-oxidation, hydrogen formation and either of two types of energy conservation systems (Rnf and Ech). Including genomes of another eleven experimentally validated chain-elongating strains, we found that the chain elongation-specific core-genome encodes the pathways for reverse β-oxidation, hydrogen formation and energy conservation, while displaying substantial genome heterogeneity. Metabolic features of these isolates are important for biotechnological applications in n-caproate and iso-butyrate production.
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Affiliation(s)
- Bin Liu
- Department of Environmental Microbiology, Helmholtz Centre for Environmental Research—UFZ, 04318 Leipzig, Germany; (B.L.); (D.P.); (H.S.); (H.H.)
| | - Denny Popp
- Department of Environmental Microbiology, Helmholtz Centre for Environmental Research—UFZ, 04318 Leipzig, Germany; (B.L.); (D.P.); (H.S.); (H.H.)
| | - Nicolai Müller
- Department of Biology, University of Konstanz, 78457 Konstanz, Germany;
| | - Heike Sträuber
- Department of Environmental Microbiology, Helmholtz Centre for Environmental Research—UFZ, 04318 Leipzig, Germany; (B.L.); (D.P.); (H.S.); (H.H.)
| | - Hauke Harms
- Department of Environmental Microbiology, Helmholtz Centre for Environmental Research—UFZ, 04318 Leipzig, Germany; (B.L.); (D.P.); (H.S.); (H.H.)
| | - Sabine Kleinsteuber
- Department of Environmental Microbiology, Helmholtz Centre for Environmental Research—UFZ, 04318 Leipzig, Germany; (B.L.); (D.P.); (H.S.); (H.H.)
- Correspondence: ; Tel.: +49-341-235-1325
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Adjusting Organic Load as a Strategy to Direct Single-Stage Food Waste Fermentation from Anaerobic Digestion to Chain Elongation. Processes (Basel) 2020. [DOI: 10.3390/pr8111487] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Production of medium chain carboxylic acids (MCCA) as renewable feedstock bio-chemicals, from food waste (FW), requires complicated reactor configurations and supplementation of chemicals to achieve product selectivity. This study evaluated the manipulation of organic loading rate in an un-supplemented, single stage stirred tank reactor to steer an anaerobic digestion (AD) microbiome towards acidogenic fermentation (AF), and thence to chain elongation. Increasing substrate availability by switching to a FW feedstock with a higher COD stimulated chain elongation. The MCCA species n-caproic (10.1 ± 1.7 g L−1) and n-caprylic (2.9 ± 0.8 g L−1) acid were produced at concentrations comparable to more complex reactor set-ups. As a result, of the adjusted operating strategy, a more specialised microbiome developed containing several MCCA-producing bacteria, lactic acid-producing Olsenella spp. and hydrogenotrophic methanogens. By contrast, in an AD reactor that was operated in parallel to produce biogas, the retention times had to be doubled when fed with the high-COD FW to maintain biogas production. The AD microbiome comprised a diverse mixture of hydrolytic and acidogenic bacteria, and acetoclastic methanogens. The results suggest that manipulation of organic loading rate and food-to-microorganism ratio may be used as an operating strategy to direct an AD microbiome towards AF, and to stimulate chain elongation in FW fermentation, using a simple, un-supplemented stirred tank set-up. This outcome provides the opportunity to repurpose existing AD assets operating on food waste for biogas production, to produce potentially higher value MCCA products, via simple manipulation of the feeding strategy.
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Draft Genome Sequences of Three Clostridia Isolates Involved in Lactate-Based Chain Elongation. Microbiol Resour Announc 2020; 9:9/32/e00679-20. [PMID: 32763935 PMCID: PMC7409852 DOI: 10.1128/mra.00679-20] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Hitherto, few species have been reported to convert lactate to n-caproate. Here, we report the high-quality draft genomes of three Clostridia strains isolated on lactate as the sole carbon source. The genomes were assembled using a hybrid short- and long-read sequencing approach. The genes involved in lactate-based chain elongation were identified. Hitherto, few species have been reported to convert lactate to n-caproate. Here, we report the high-quality draft genomes of three Clostridia strains isolated on lactate as the sole carbon source. The genomes were assembled using a hybrid short- and long-read sequencing approach. The genes involved in lactate-based chain elongation were identified.
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Liu B, Kleinsteuber S, Centler F, Harms H, Sträuber H. Competition Between Butyrate Fermenters and Chain-Elongating Bacteria Limits the Efficiency of Medium-Chain Carboxylate Production. Front Microbiol 2020; 11:336. [PMID: 32210937 PMCID: PMC7067704 DOI: 10.3389/fmicb.2020.00336] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2019] [Accepted: 02/17/2020] [Indexed: 01/08/2023] Open
Abstract
Medium-chain carboxylates such as n-caproate and n-caprylate are valuable chemicals, which can be produced from renewable feedstock by anaerobic fermentation and lactate-based microbial chain elongation. Acidogenic microbiota involved in lactate-based chain elongation and their interplay with lactic acid bacteria have not been characterized in detail yet. Here, the metabolic and community dynamics were studied in a continuous bioreactor with xylan and lactate as sole carbon sources. Four succession stages were observed during 148 days of operation. After an adaptation period of 36 days, a relatively stable period of 28 days (stage I) was reached with n-butyrate, n-caproate and n-caprylate productivities of 7.2, 8.2 and 1.8 gCOD L-1 d-1, respectively. After a transition period, the process changed to another period (stage II), during which 46% more n-butyrate, 51% less n-caproate and 67% less n-caprylate were produced. Co-occurrence networks of species based on 16S rRNA amplicon sequences and correlations with process parameters were analyzed to infer ecological interactions and potential metabolic functions. Diverse functions including hydrolysis of xylan, primary fermentation of xylose to acids (e.g., to acetate by Syntrophococcus, to n-butyrate by Lachnospiraceae, and to lactate by Lactobacillus) and chain-elongation with lactate (by Ruminiclostridium 5 and Pseudoramibacter) were inferred from the metabolic network. In stage I, the sub-network characterized by strongest positive correlations was mainly related to the production of n-caproate and n-caprylate. Lactic acid bacteria of the genus Olsenella co-occurred with potentially chain-elongating bacteria of the genus Pseudoramibacter, and their abundance was positively correlated with n-caproate and n-caprylate concentrations. A new sub-network appeared in stage II, which was mainly related to n-butyrate production and revealed a network of different lactic acid bacteria (Bifidobacterium) and potential n-butyrate producers (Clostridium sensu stricto 12). The synergy effects between lactate-producing and lactate-consuming bacteria constitute a division of labor cooperation of mutual benefit. Besides cooperation, competition between different taxa determined the bacterial community assembly over the four succession stages in this resource-limited system. During long-term reactor operation under constant conditions, chain-elongating bacteria were outcompeted by butyrate-producing bacteria, leading to the increase of n-butyrate yield at the cost of medium-chain carboxylate yields in this closed model system.
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Affiliation(s)
| | | | | | | | - Heike Sträuber
- Department of Environmental Microbiology, Helmholtz Centre for Environmental Research – UFZ, Leipzig, Germany
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Syngas-aided anaerobic fermentation for medium-chain carboxylate and alcohol production: the case for microbial communities. Appl Microbiol Biotechnol 2019; 103:8689-8709. [PMID: 31612269 DOI: 10.1007/s00253-019-10086-9] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2019] [Revised: 08/06/2019] [Accepted: 08/07/2019] [Indexed: 01/01/2023]
Abstract
Syngas fermentation has been successfully implemented in commercial-scale plants and can enable the biochemical conversion of the driest fractions of biomass through synthesis gas (H2, CO2, and CO). The process relies on optimized acetogenic strains able to reach and maintain high productivity of ethanol and acetate. In parallel, microbial communities have shown to be the best choice for the production of valuable medium-chain carboxylates through anaerobic fermentation of biomass, demanding low technical complexity and being able to realize simultaneous hydrolysis of the substrate. Each of the two technologies benefits from different strong points and has different challenges to overcome. This review discusses the rationales for merging these two seemingly disparate technologies by analyzing previous studies and drawing opinions based on the lessons learned from such studies. For keeping the technical demands of the resulting process low, a case is built for using microbial communities instead of pure strains. For that to occur, a shift from conventional syngas-based to "syngas-aided" anaerobic fermentation is suggested. Strategies for tackling the intricacies of working simultaneously with communities and syngas, such as competing pathways, and thermodynamic aspects are discussed as well as the stoichiometry and economic feasibility of the concept. Overall, syngas-aided anaerobic fermentation seems to be a promising concept for the biorefinery of the future. However, the effects of process parameters on microbial interactions have to be understood in greater detail, in order to achieve and sustain feasible medium-chain carboxylate and alcohol productivity.
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