Publicação
Isolation and characterization of two novel thermophilic anaerobic bacteria from syngas - and carbon monoxide - degrading cultures
| Resumo: | Syn(thesis)gas is a mixture containing hydrogen, carbon monoxide and carbon dioxide, in variable ratios. Syngas is commonly produced from fossil fuels, but it can be generated from a vast array of feedstocks such as lignocellulosic biomass and carbon-based wastes, including recalcitrant wastes. Production of biofuels and bulk chemicals from syngas, both by thermochemical or microbial processes, is a field of promising technological developments. In this work, thermophilic (55ºC) enrichment series were promoted using syngas (60% CO, 30% H2 and 10% CO2, enrichment series T-SYN) and carbon monoxide (100% CO, enrichment series T-CO). Thermophilic anaerobic sludge from a full-scale waste digester was used as inoculum for the enrichment cultures. Cultures were incubated in batch and, once CO was completely depleted, transferred and supplied with equal or increased CO partial pressure. Stable enriched cultures able to degrade syngas/CO were obtained after subsequent transfer for over a year. Acetate and CO2 were the main products resulting from syngas conversion by T-SYN, while acetate, CO2 and hydrogen were formed in cultures T-CO. Species from the genera Desulfotomaculum and Caloribacterium, and Thermincola and Thermoanaerobacter, were predominant in T-SYN and in T-CO enrichments, respectively. Two novel strains were isolated from enrichments using serial dilutions, pasteurization, autoclaving and incubation with different substrates. From enrichment culture T-SYN, a Thermoanaerobacter sp., strain PCO, was isolated, for which the closest phylogenetic relative is Thermoanaerobacter thermohydrosulfuricus (96% similarity based on 16S rRNA). Moorella sp., strain E3-O, which is phylogenetically related to Moorella glycerini (97% similarity based on 16S rRNA), was isolated from enrichment culture T-CO. Strain E3-O converts CO to mainly hydrogen (0.75 molH2/mol CO) and low amounts of acetate (0.08 molacetate/molCO). Strain PCO does not utilize CO, but is able to grow in the presence of high CO concentration (100 mM). The isolation of a new hydrogenogenic CO-oxidizing thermophilic strain, strain E3-O, represents an important contribution to further exploration and understanding of microbes involved in syngas and/or CO conversion. |
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| Autores principais: | Alves, J. I. |
| Outros Autores: | Alves, M. M.; Stams, Alfons Johannes Maria; Plugge, C. M.; Sousa, D. Z. |
| Ano: | 2012 |
| País: | Portugal |
| Tipo de documento: | outro |
| Tipo de acesso: | acesso aberto |
| Instituição associada: | Universidade do Minho |
| Idioma: | inglês |
| Origem: | RepositóriUM - Universidade do Minho |
| Resumo: | Syn(thesis)gas is a mixture containing hydrogen, carbon monoxide and carbon dioxide, in variable ratios. Syngas is commonly produced from fossil fuels, but it can be generated from a vast array of feedstocks such as lignocellulosic biomass and carbon-based wastes, including recalcitrant wastes. Production of biofuels and bulk chemicals from syngas, both by thermochemical or microbial processes, is a field of promising technological developments. In this work, thermophilic (55ºC) enrichment series were promoted using syngas (60% CO, 30% H2 and 10% CO2, enrichment series T-SYN) and carbon monoxide (100% CO, enrichment series T-CO). Thermophilic anaerobic sludge from a full-scale waste digester was used as inoculum for the enrichment cultures. Cultures were incubated in batch and, once CO was completely depleted, transferred and supplied with equal or increased CO partial pressure. Stable enriched cultures able to degrade syngas/CO were obtained after subsequent transfer for over a year. Acetate and CO2 were the main products resulting from syngas conversion by T-SYN, while acetate, CO2 and hydrogen were formed in cultures T-CO. Species from the genera Desulfotomaculum and Caloribacterium, and Thermincola and Thermoanaerobacter, were predominant in T-SYN and in T-CO enrichments, respectively. Two novel strains were isolated from enrichments using serial dilutions, pasteurization, autoclaving and incubation with different substrates. From enrichment culture T-SYN, a Thermoanaerobacter sp., strain PCO, was isolated, for which the closest phylogenetic relative is Thermoanaerobacter thermohydrosulfuricus (96% similarity based on 16S rRNA). Moorella sp., strain E3-O, which is phylogenetically related to Moorella glycerini (97% similarity based on 16S rRNA), was isolated from enrichment culture T-CO. Strain E3-O converts CO to mainly hydrogen (0.75 molH2/mol CO) and low amounts of acetate (0.08 molacetate/molCO). Strain PCO does not utilize CO, but is able to grow in the presence of high CO concentration (100 mM). The isolation of a new hydrogenogenic CO-oxidizing thermophilic strain, strain E3-O, represents an important contribution to further exploration and understanding of microbes involved in syngas and/or CO conversion. |
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