Microbial community structure and chemical composition from dark earth in a native archaeological site of the Lower Amazon

Abstract

The microbial community structure from dark earth in a native archaeological site of the Lower Amazon was analyzed by PCR-DGGE, using 16S rRNA gene for prokaryote population and 18S rDNA and ITS regions (using clamp GC) for the eukaryote population. The bands were excised from gel and re-amplified for sequencing. The diversity found according to the region of amplification showed same profiles for the two primers pairs. The bacteria genus were: Bacillus, Klebsiella, Pantoea, Enterobacter, Lactobacillus, Escherichia, Leuconostoc and actinobacterias as Streptomyces and Microbacterium. Among the fungal community was Zygosaccharomyces, Lachancea, Saccharomyces, Cladosporium, Candida, Penicillium and Uncultured ascomycota and zygomycete were found. Molecular approaches revealed microbial groups that have never been reported in Lower Amazon soil as the Leuconostoc mesenteroides, Lactobacillus casei and Lactobacillus paracasei bacteria’s and Lachancea meyersii yeast. The soil pH was ~6.5; the soil had high levels of minerals with exception of Na (not detected) and Al (~0.2 mg/dm3). The organic matter was 3.5 dag/kg. This study also shows that the Amazon soil is rich in minerals. This can be an important factor in the species richness in the Amazon region. The present data show that the Lower Amazon represents a vast resource for the biotechnology area.