Investigation of heterotrophic microbial communities in immediate vicinity of hydrothermal vents

In this study we analyzed samples taken at Menez Gwen hydrothermal vent field from different parts along the mixing gradients at small spatial scales (cm to m) Sampling areas comprise diffuse fluid discharge points, the immediate surroundings of discharge, and the buoyant parts of hydrothermal plumes. Employing high throughput 16S rRNA gene tag sequencing, CARD-FISH, and targeted metagenomics, we found a distinct microbial community directly adjacent to the venting orifices dominated by chemolithoautotrophic bacteria. This community is enriched in Alpha- and Gammaproteobacteria with versatile heterotrophic potential. We propose that hotspots of chemolithoautotrophic life support a “belt” of heterotrophic bacteria which differ significantly from the oligotrophic microbiota of the deep sea.