Metagenomic Analysis of Microbial Communities in the Soil-mousse Surrounding of an Amazonian Geothermal Spring in Peru

Aim: Aguas Calientes (AC) is one of the very few geothermal springs located deep into the Amazon rainforest in Peru. The main aim of this study was to generate an illumina based high resolution microbial phylogenetic profile of the soil-mousse surrounding of an Amazonian geothermal spring like AC.

Study Design: Soil-mousse surrounding of AC geothermal spring was subjected to metagenome sequencing using Illumina HiSeq platform.

Place and Duration of Study: Soil samples were collected from the surrounding of Aguas Calientes (7°21'12'' S, 75°00'54'' W). The duration of the study was from 2013-2016.

Methodology: Metagenomic DNA was extracted from pooled soil samples using PowerSoil® DNA isolation kit and analyzed at 16S rRNA V3-V4 hypervariable region by amplicon metagenome sequencing on Illumina Hiseq platform. QIIME pipeline was used for 16S RNA detection, clustering and Operational Taxonomic Units (OTUs) picking followed by Biom file generation and statistical analysis. Functional analysis of 16S amplicons was performed using the default settings of PICRUSt.

Results: A total of 72 bacterial phyla and 3 archaeal phyla were detected in AC soil. Proteobacteria (50.09%) was found to be the highest represented phylum among bacterial communities while among archaeal communities Crenarchaeota (0.26%) dominated the sample. More than 50% of the sequences in AC soil were found unidentified/novel at the genus level. A plausible facultative mutualistic relationship was predicted among some members of the communities. In Clusters of Orthologs (COGs) analysis, most of the sequences were found to be associated with “Amino acid transport and metabolism” (8.3%) category, while among predicted Kyoto Encyclopedia of Genes and Genomes (KEGGs) pathways "Membrane transport" (12.1%) was the most abundant one.

Conclusion: This is the first report of a high resolution microbial phylogenetic profile of an Amazonian geothermal spring soil-mousse surrounding. Although a very diverse group of the bacterial and archaeal population was observed in the sample, a large portion of unidentified thermophilic microbial members was also noticed which need to be studied.