Hydrothermal systems form at divergent and convergent boundaries of lithospheric plates and within plates due to weakened crust and mantle plumes, playing host to diverse microbial ecosystems. Little is known of how differences in tectonic setting influence the geochemical and microbial compositions of these hydrothermal ecosystems. Here, coordinated geochemical and microbial community analyses were conducted on 87 high‐temper...

Summary Many microbial phyla that are widely distributed in open environments have few or no representatives within animal‐associated microbiota. Among them, the C hloroflexi comprises taxonomically and physiologically diverse lineages adapted to a wide range of aquatic and terrestrial habitats. A distinct group of uncultured chloroflexi related to free‐living anaerobic A naerolineae inhabits the mammalian gastrointestinal tra...

Summary Next‐generation sequencing has dramatically changed the landscape of microbial ecology, large‐scale and in‐depth diversity studies being now widely accessible. However, determining the accuracy of taxonomic and quantitative inferences and comparing results obtained with different approaches are complicated by incongruence of experimental and computational data types and also by lack of knowledge of the true ecological...

Summary To evaluate the effects of local fluid geochemistry on microbial communities associated with active hydrothermal vent deposits, we examined the archaeal and bacterial communities of 12 samples collected from two very different vent fields: the basalt‐hosted Lucky Strike (37°17′N, 32°16.3′W, depth 1600–1750 m) and the ultramafic‐hosted Rainbow (36°13′N, 33°54.1′W, depth 2270–2330 m) vent fields along the Mid‐Atlantic Ri...