Resumo

Tropical peatland ecosystems represent one of the largest terrestrial organic carbon sinks. Degradation of plant biomass in peat swamps is slow owing to high acidity, anoxic conditions, and the accumulation of recalcitrant materials which may restrict microbial activity. Information on microbial diversity and the underlying biogeochemical processes of this unique ecosystem would allow us to better utilize and manage microbial bioresources, and to improve conservation efforts. This study evaluated the communities of Bacteria and Archaea from peat bogs of Santo Amaro das Brotas, Sergipe State, Brazil. Samples of peat were collected from 20 cm depth and combined to form a single composite sample for DNA extraction and construction of 16S rDNA libraries. Sequences were processed and classified taxonomically using the program Mothur and RDP database. The bacterial community showed a great diversity, being detected 11 phyla with predominance of Proteobacteria (50%) and Acidobacteria (17%). Alphaproteobacteria was represented mainly by the orders Rhizobiales and Rhodospirillales, and Deltaproteobacteria by order Syntrophobacterales. Although to a lesser extent, were detected sequences affiliated with members of the phyla Actinobacteria, Planctomycetes, Spirochaetes, Chlorobi, Firmicutes and Verrucomicrobia. The Domain Archaea comprised Euryarchaeota and Crenarcheaota, the latter being more abundant. In Euryarchaeota there was a dominance of methanogenic of the class Methanomicrobia, while the Crenarchaeota was composed only by the class Termoprotei, organisms found in environments with low oxygen and acidic pH. Archaea presented itself as a community richer and more diverse than Bacteria. The results contribute to the knowledge of peat microbial diversity and show the potential of partial carbon flux from biomass degradation through methanogenesis.