In order to expand the baseline knowledge of microbial ecosystems from deep-sea hydrothermal vent systems located on the Central and South-East Indian Ridge, hydrothermal fluids, massive sulfides, ambient water and sediments of six distinct vent fields were sampled. Most of these vent sites were only recently discovered in the course of the German exploration program for massive sulfide deposits and no previous studies of the respective microbial communities exist. The here presented study aims at expanding the baseline knowledge of microbial ecosystems in putative deep-sea mining areas by assessing the microbial communities and their putative metabolisms, inferred by 16S rRNA analyses.