RESUMO
The present study for the first time investigated the diversity of methanotrophs in a biogas reactor running on cattle dung by sequence analysis of the "functional" gene, particulate methane monooxygenase A (pmoA). Community structure was determined by operational taxonomic unit (OTU) phylogenetic analyses of 396 clones belonging to pmoA library. On the basis of 95% peptide identity, 396 inferred PmoA peptide sequences were clustered in 22 phylotypes. These OTUS were phylogenetically affiliated to alpha-proteobacteria (5.30% clones) and gamma-proteobacteria (94.7% clones) and were only distantly related to those of known methanotrophs, indicating the existence of unknown methanotrophs involved in aerobic methanotrophy inside the biogas plant. Good's coverage indicated that the present library covered 96.21% of the dominant species that could be cloned from the biogas reactor. The molecular approaches used in this study provided useful description of the microbial community involved in aerobic oxidation of methane.
Assuntos
Proteínas de Bactérias/genética , Biodiversidade , Reatores Biológicos/microbiologia , Metano/metabolismo , Oxigenases/genética , Proteobactérias/isolamento & purificação , Animais , Proteínas de Bactérias/metabolismo , Bovinos , Dados de Sequência Molecular , Oxigenases/metabolismo , Filogenia , Proteobactérias/classificação , Proteobactérias/enzimologia , Proteobactérias/genéticaRESUMO
The methanogen community in biogas reactor running on cattle dung was investigated in two different seasons; summer (April, 36 degrees C) and winter (December, 24 degrees C), in the year 2004 by a culture-independent approach. Community structure was determined by phylogenetic analyses of 343 and 278 mcrA clones belonging to summer and winter month libraries, respectively. In summer month's library, 41.7% clones were affiliated to Methanomicrobiales, 30% to Methanosarcinales, 19% to Methanobacteriales, 5% to Methanococcales and a total of 4.3% clones belonged to unclassified euryarchaeotal lineages. In winter month's library, Methanomicrobiales encompassed 98.6% clones, and Methanobacteriales included 1.4% of total clone diversity. Biogas plant performance data collected during the winter month indicated significant reduction in daily biogas produced as compared to summer month because of lowering in ambient temperature and associated shift in microbial community. Results from this molecular study showed the existence of highly diverse and complex methanogens communities present in biogas plant.
