Methane-yielding microbial communities processing lactate-rich substrates: a piece of the anaerobic digestion puzzle
Abstract Background Anaerobic digestion, whose final products are methane and carbon dioxide, ensures energy flow and circulation of matter in ecosystems. This naturally occurring process is used for the production of renewable energy from biomass. Lactate, a common product of acidic fermentation, i...
| Main Authors: | , , , , , , , , , |
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| Format: | Article |
| Language: | English |
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BMC
2018-04-01
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| Series: | Biotechnology for Biofuels |
| Subjects: | |
| Online Access: | http://link.springer.com/article/10.1186/s13068-018-1106-z |
| _version_ | 1829104210977751040 |
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| author | Anna Detman Damian Mielecki Łukasz Pleśniak Michał Bucha Marek Janiga Irena Matyasik Aleksandra Chojnacka Mariusz-Orion Jędrysek Mieczysław K. Błaszczyk Anna Sikora |
| author_facet | Anna Detman Damian Mielecki Łukasz Pleśniak Michał Bucha Marek Janiga Irena Matyasik Aleksandra Chojnacka Mariusz-Orion Jędrysek Mieczysław K. Błaszczyk Anna Sikora |
| author_sort | Anna Detman |
| collection | DOAJ |
| description | Abstract Background Anaerobic digestion, whose final products are methane and carbon dioxide, ensures energy flow and circulation of matter in ecosystems. This naturally occurring process is used for the production of renewable energy from biomass. Lactate, a common product of acidic fermentation, is a key intermediate in anaerobic digestion of biomass in the environment and biogas plants. Effective utilization of lactate has been observed in many experimental approaches used to study anaerobic digestion. Interestingly, anaerobic lactate oxidation and lactate oxidizers as a physiological group in methane-yielding microbial communities have not received enough attention in the context of the acetogenic step of anaerobic digestion. This study focuses on metabolic transformation of lactate during the acetogenic and methanogenic steps of anaerobic digestion in methane-yielding bioreactors. Results Methane-yielding microbial communities instead of pure cultures of acetate producers were used to process artificial lactate-rich media to methane and carbon dioxide in up-flow anaerobic sludge blanket reactors. The media imitated the mixture of acidic products found in anaerobic environments/digesters where lactate fermentation dominates in acidogenesis. Effective utilization of lactate and biogas production was observed. 16S rRNA profiling was used to examine the selected methane-yielding communities. Among Archaea present in the bioreactors, the order Methanosarcinales predominated. The acetoclastic pathway of methane formation was further confirmed by analysis of the stable carbon isotope composition of methane and carbon dioxide. The domain Bacteria was represented by Bacteroidetes, Firmicutes, Proteobacteria, Synergistetes, Actinobacteria, Spirochaetes, Tenericutes, Caldithrix, Verrucomicrobia, Thermotogae, Chloroflexi, Nitrospirae, and Cyanobacteria. Available genome sequences of species and/or genera identified in the microbial communities were searched for genes encoding the lactate-oxidizing metabolic machinery homologous to those of Acetobacterium woodii and Desulfovibrio vulgaris. Furthermore, genes for enzymes of the reductive acetyl-CoA pathway were present in the microbial communities. Conclusions The results indicate that lactate is oxidized mainly to acetate during the acetogenic step of AD and this comprises the acetotrophic pathway of methanogenesis. The genes for lactate utilization under anaerobic conditions are widespread in the domain Bacteria. Lactate oxidation to the substrates for methanogens is the most energetically attractive process in comparison to butyrate, propionate, or ethanol oxidation. |
| first_indexed | 2024-12-12T04:57:14Z |
| format | Article |
| id | doaj.art-2131b53c6a27459f94d5557ba1695d29 |
| institution | Directory Open Access Journal |
| issn | 1754-6834 |
| language | English |
| last_indexed | 2024-12-12T04:57:14Z |
| publishDate | 2018-04-01 |
| publisher | BMC |
| record_format | Article |
| series | Biotechnology for Biofuels |
| spelling | doaj.art-2131b53c6a27459f94d5557ba1695d292022-12-22T00:37:19ZengBMCBiotechnology for Biofuels1754-68342018-04-0111111810.1186/s13068-018-1106-zMethane-yielding microbial communities processing lactate-rich substrates: a piece of the anaerobic digestion puzzleAnna Detman0Damian Mielecki1Łukasz Pleśniak2Michał Bucha3Marek Janiga4Irena Matyasik5Aleksandra Chojnacka6Mariusz-Orion Jędrysek7Mieczysław K. Błaszczyk8Anna Sikora9Department of Molecular Biology, Institute of Biochemistry and Biophysics, Polish Academy of SciencesDepartment of Molecular Biology, Institute of Biochemistry and Biophysics, Polish Academy of SciencesDepartment of Molecular Biology, Institute of Biochemistry and Biophysics, Polish Academy of SciencesFaculty of Earth Sciences, University of Silesia in KatowiceOil and Gas Institute, National Research InstituteOil and Gas Institute, National Research InstituteDepartment of Molecular Biology, Institute of Biochemistry and Biophysics, Polish Academy of SciencesInstitute of Geological Sciences, University of WroclawFaculty of Agriculture and Biology, Warsaw University of Life SciencesDepartment of Molecular Biology, Institute of Biochemistry and Biophysics, Polish Academy of SciencesAbstract Background Anaerobic digestion, whose final products are methane and carbon dioxide, ensures energy flow and circulation of matter in ecosystems. This naturally occurring process is used for the production of renewable energy from biomass. Lactate, a common product of acidic fermentation, is a key intermediate in anaerobic digestion of biomass in the environment and biogas plants. Effective utilization of lactate has been observed in many experimental approaches used to study anaerobic digestion. Interestingly, anaerobic lactate oxidation and lactate oxidizers as a physiological group in methane-yielding microbial communities have not received enough attention in the context of the acetogenic step of anaerobic digestion. This study focuses on metabolic transformation of lactate during the acetogenic and methanogenic steps of anaerobic digestion in methane-yielding bioreactors. Results Methane-yielding microbial communities instead of pure cultures of acetate producers were used to process artificial lactate-rich media to methane and carbon dioxide in up-flow anaerobic sludge blanket reactors. The media imitated the mixture of acidic products found in anaerobic environments/digesters where lactate fermentation dominates in acidogenesis. Effective utilization of lactate and biogas production was observed. 16S rRNA profiling was used to examine the selected methane-yielding communities. Among Archaea present in the bioreactors, the order Methanosarcinales predominated. The acetoclastic pathway of methane formation was further confirmed by analysis of the stable carbon isotope composition of methane and carbon dioxide. The domain Bacteria was represented by Bacteroidetes, Firmicutes, Proteobacteria, Synergistetes, Actinobacteria, Spirochaetes, Tenericutes, Caldithrix, Verrucomicrobia, Thermotogae, Chloroflexi, Nitrospirae, and Cyanobacteria. Available genome sequences of species and/or genera identified in the microbial communities were searched for genes encoding the lactate-oxidizing metabolic machinery homologous to those of Acetobacterium woodii and Desulfovibrio vulgaris. Furthermore, genes for enzymes of the reductive acetyl-CoA pathway were present in the microbial communities. Conclusions The results indicate that lactate is oxidized mainly to acetate during the acetogenic step of AD and this comprises the acetotrophic pathway of methanogenesis. The genes for lactate utilization under anaerobic conditions are widespread in the domain Bacteria. Lactate oxidation to the substrates for methanogens is the most energetically attractive process in comparison to butyrate, propionate, or ethanol oxidation.http://link.springer.com/article/10.1186/s13068-018-1106-zAnaerobic lactate oxidationAcetogenic step of anaerobic digestionWood–Ljungdahl pathwayMicrobial communities16S rRNA profilingGenome search |
| spellingShingle | Anna Detman Damian Mielecki Łukasz Pleśniak Michał Bucha Marek Janiga Irena Matyasik Aleksandra Chojnacka Mariusz-Orion Jędrysek Mieczysław K. Błaszczyk Anna Sikora Methane-yielding microbial communities processing lactate-rich substrates: a piece of the anaerobic digestion puzzle Biotechnology for Biofuels Anaerobic lactate oxidation Acetogenic step of anaerobic digestion Wood–Ljungdahl pathway Microbial communities 16S rRNA profiling Genome search |
| title | Methane-yielding microbial communities processing lactate-rich substrates: a piece of the anaerobic digestion puzzle |
| title_full | Methane-yielding microbial communities processing lactate-rich substrates: a piece of the anaerobic digestion puzzle |
| title_fullStr | Methane-yielding microbial communities processing lactate-rich substrates: a piece of the anaerobic digestion puzzle |
| title_full_unstemmed | Methane-yielding microbial communities processing lactate-rich substrates: a piece of the anaerobic digestion puzzle |
| title_short | Methane-yielding microbial communities processing lactate-rich substrates: a piece of the anaerobic digestion puzzle |
| title_sort | methane yielding microbial communities processing lactate rich substrates a piece of the anaerobic digestion puzzle |
| topic | Anaerobic lactate oxidation Acetogenic step of anaerobic digestion Wood–Ljungdahl pathway Microbial communities 16S rRNA profiling Genome search |
| url | http://link.springer.com/article/10.1186/s13068-018-1106-z |
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