Culturable bacteria from soils of the Brazilian Cerrado in Minas Gerais state

Abstract

The diversity of culturable soil bacteria from the Cerrado biome in the state of Minas Gerais, Brazil was evaluated. Soil samples were collected from the regions of Passos, Arcos and Luminárias during the rainy and dry seasons. Distinct bacterial morphotypes were isolated by culturing in Nutrient Agar (NA), Eosin Methylene Blue (EMB) and NA, pH 4.5. The isolates were first grouped based on their morphological and biochemical characterization, then characterized by Repetitive Extragenic Palindromic-Polymerase Chain Reaction (REP-PCR) and finally identified by 16S rRNA gene sequencing. Thirteen bacterial genera (Arthrobacter, Bacillus, Hafnia, Lysinibacillus, Paenibacillus, Pseudomonas, Serratia, Staphylococcus, Streptomyces, Rhizobium, Rummeliibacillus, Enterobacter and Microbacterium) and the distinct species belonging to these genera were identified. The presence of 39 operational taxonomic units (OTUs) during the rainy season and 30 OTUs during the dry season was observed. The Shannon index (H') and Simpson index (D) for each region were compared, with simultaneous consideration of both the rainy and dry seasons. This is the first report of changes in the diversity of culturable bacterial using ecological indicators from the three study regions as a function of seasonal conditions. This suggests that culturable bacterial in Brazilian Cerrado soils may represent a vast unexplored resource for biotechnology.