Dataset Information

Enrichment of syngas-converting communities from a multi-orifice baffled bioreactor.

ABSTRACT: The substitution of natural gas by renewable biomethane is an interesting option to reduce global carbon footprint. Syngas fermentation has potential in this context, as a diverse range of low-biodegradable materials that can be used. In this study, anaerobic sludge acclimatized to syngas in a multi-orifice baffled bioreactor (MOBB) was used to start enrichments with CO. The main goals were to identify the key players in CO conversion and evaluate potential interspecies metabolic interactions conferring robustness to the process. Anaerobic sludge incubated with 0.7 × 105 Pa CO produced methane and acetate. When the antibiotics vancomycin and/or erythromycin were added, no methane was produced, indicating that direct methanogenesis from CO did not occur. Acetobacterium and Sporomusa were the predominant bacterial species in CO-converting enrichments, together with methanogens from the genera Methanobacterium and Methanospirillum. Subsequently, a highly enriched culture mainly composed of a Sporomusa sp. was obtained that could convert up to 1.7 × 105 Pa CO to hydrogen and acetate. These results attest the role of Sporomusa species in the enrichment as primary CO utilizers and show their importance for methane production as conveyers of hydrogen to methanogens present in the culture.

SUBMITTER: Arantes AL

PROVIDER: S-EPMC6011948 | biostudies-literature | 2018 Jul

REPOSITORIES: biostudies-literature

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Enrichment of syngas-converting communities from a multi-orifice baffled bioreactor.

Arantes Ana L AL Alves Joana I JI Stams Alfons J M AJM Alves M Madalena MM Sousa Diana Z DZ

Microbial biotechnology 20171121 4

The substitution of natural gas by renewable biomethane is an interesting option to reduce global carbon footprint. Syngas fermentation has potential in this context, as a diverse range of low-biodegradable materials that can be used. In this study, anaerobic sludge acclimatized to syngas in a multi-orifice baffled bioreactor (MOBB) was used to start enrichments with CO. The main goals were to identify the key players in CO conversion and evaluate potential interspecies metabolic interactions co ...[more]

PMID: 29160026

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Project description:Background:The production of ethanol through the biochemical conversion of syngas, a mixture of H2, CO and CO2, has been typically studied using pure cultures. However, mixed microbial consortia may offer a series of benefits such as higher resilience and adaptive capacity, and non-sterile operation, all of which contribute to reducing the utility consumption when compared to pure culture-based processes. This work focuses on the study of strategies for the enrichment of mixed microbial consortia with high ethanologenic potential, investigating the effect of the operational conditions (pH and yeast extract addition) on both the ethanol yield and evolution of the microbial community along the enrichment process. The pH was selected as the main driver of the enrichment as it was expected to be a crucial parameter for the selection of carboxydotrophic bacteria with high ethanologenic potential. Additionally, a thermodynamic analysis of the network of biochemical reactions carried out by syngas-converting microbial consortia was performed and the potential of using thermodynamics as a basis for the selection of operational parameters favoring a specific microbial activity was evaluated. Results:All enriched consortia were dominated by the genus Clostridium with variable microbial diversity and species composition as a function of the enrichment conditions. The ethanologenic potential of the enriched consortia was observed to increase as the initial pH was lowered, achieving an ethanol yield of 59.2?±?0.2% of the theoretical maximum in the enrichment at pH 5. On the other hand, yeast extract addition did not affect the ethanol yield, but triggered the production of medium-chain fatty acids and alcohols. The thermodynamic analysis of the occurring biochemical reactions allowed a qualitative prediction of the activity of microbial consortia, thus enabling a more rational design of the enrichment strategies targeting specific activities. Using this approach, an improvement of 22.5% over the maximum ethanol yield previously obtained was achieved, reaching an ethanol yield of 72.4?±?2.1% of the theoretical maximum by increasing the initial acetate concentration in the fermentation broth. Conclusions:This study demonstrated high product selectivity towards ethanol using mixed microbial consortia. The thermodynamic analysis carried out proved to be a valuable tool for interpreting the metabolic network of microbial consortia-driven processes and designing microbial-enrichment strategies targeting specific biotransformations.

Project description:Patterns of precipitation and nitrogen (N) deposition are changing in ecosystems worldwide. Simultaneous increases in precipitation and N deposition can relieve co-limiting soil resource conditions for plants and result in synergistic plant responses, which may affect animals and plant responses to higher trophic levels. However, the potential for synergistic effects of precipitation and N deposition on animals and plant responses to herbivores and predators (via trophic cascades) is unclear. We investigated the influence of precipitation and N enrichment on ecological dynamics across three trophic levels, hypothesizing that herbivores and plants would exhibit synergistic responses to the combined influence of precipitation, N amendments and predators. To test this, we conducted a field experiment with arthropods on two model plant species, Nicotiana tabacum and Nicotiana rustica. First, we characterized the plant-arthropod assemblages, finding that N. tabacum hosted greater abundances of caterpillars, while N. rustica hosted more sap-sucking herbivores. Next, we evaluated the effects of rainwater, soil N, and predatory spider manipulations for both plant-arthropod assemblages. On N. tabacum, water and N availability had an interactive effect on caterpillars, where caterpillars were most abundant with rainwater additions and least abundant when both rainwater and N were added. For N. rustica, foliar chemistry had a synergistic response to all three experimental factors. Compared to spider-absent conditions, leaf N concentration increased and C/N decreased when spiders were present, but this response only occurred under high water and N availability. Spiders indirectly altered plant chemistry via a facilitative effect of spiders on sap-sucking herbivores, potentially due to intra-guild predation, and a positive effect of sap-suckers on foliar N concentration. Our study suggests that predictions of the ecological impacts of altered precipitation and N deposition may need to account for the effects of resource co-limitation on dynamics across trophic levels.

Dataset Information

Enrichment of syngas-converting communities from a multi-orifice baffled bioreactor.

Publications

Enrichment of syngas-converting communities from a multi-orifice baffled bioreactor.

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