Abstract
A taxonomic and annotated functional description of microbial life was deduced from 53 Mb of metagenomic sequence retrieved from a planktonic fraction of the Neotropical high Andean (3,973 meters above sea level) acidic hot spring El Coquito (EC). A classification of unassembled metagenomic reads using different databases showed a high proportion of Gammaproteobacteria and Alphaproteobacteria (in total read affiliation), and through taxonomic affiliation of 16S rRNA gene fragments we observed the presence of Proteobacteria, micro-algae chloroplast and Firmicutes. Reads mapped against the genomes Acidiphilium cryptum JF-5, Legionella pneumophila str. Corby and Acidithiobacillus caldus revealed the presence of transposase-like sequences, potentially involved in horizontal gene transfer. Functional annotation and hierarchical comparison with different datasets obtained by pyrosequencing in different ecosystems showed that the microbial community also contained extensive DNA repair systems, possibly to cope with ultraviolet radiation at such high altitudes. Analysis of genes involved in the nitrogen cycle indicated the presence of dissimilatory nitrate reduction to N2 (narGHI, nirS, norBCDQ and nosZ), associated with Proteobacteria-like sequences. Genes involved in the sulfur cycle (cysDN, cysNC and aprA) indicated adenylsulfate and sulfite production that were affiliated to several bacterial species. In summary, metagenomic sequence data provided insight regarding the structure and possible functions of this hot spring microbial community, describing some groups potentially involved in the nitrogen and sulfur cycling in this environment.
Highlights
The Colombian Andean region is characterized by high volcanic activity, comprising part of the region called the ‘‘Ring of Fire’’, and is considered a hotspot for biodiversity [1]
We carried out a metagenomic analysis of the planktonic microbial community present in El Coquito (EC) hot spring located in the Colombian Andes (Figure 1)
As a complement to a previous 16S rRNA gene analysis [3], and in order to assess the microbial community structure using direct sequencing, the metabolic pathways were evaluated and the major players involved in nitrogen and sulfur transformations were identified
Summary
The Colombian Andean region is characterized by high volcanic activity, comprising part of the region called the ‘‘Ring of Fire’’, and is considered a hotspot for biodiversity [1]. In acidic hot springs the most representative genera described are Acidithiobacillus, Acidimicrobium, Sulfobacillus, Thiomonas, Leptospirillum and Hydrogenobaculum [7,8] These chemolithotrophic acidophiles are often the predominant primary producers and may contribute to iron and sulfur cycling via oxidization of reduced inorganic sulfur and ferrous iron compounds [9]. In extremely acidic and UV lightirradiated environments, primary production may be mediated by mesophilic phototrophic acidophiles (mainly eukaryotic micro-algae) [11] Many of these studies have assessed microbial diversity by 16S rRNA gene analysis [12,13,14], which is useful but does not provide information on ecologically relevant genes involved in various biogeochemical cycles
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