Bacterial diversity in a subseafloor habitat following a deep-sea volcanic eruption

The bacterial diversity in a diffuse flow hydrothermal vent habitat at Axial Volcano, Juan de Fuca Ridge was examined shortly after an eruptive event in 1998 and again in 1999 and 2000 using PCR-amplified 16S rRNA gene sequence analyses. While considerable overlap with deep-sea background seawater was found within the alpha- and gamma-proteobacteria, unique subseafloor phylotypes were distinguishable. These included diverse members of the epsilon-proteobacteria, high temperature groups such as Desulfurobacterium, Gram-positive bacteria, and members of novel candidate divisions WS6 and ABY1. Phylotype richness was highest in the particle-attached populations from all three sampling periods, and diversity appeared to increase over that time, particularly among the epsilon-proteobacteria. A preliminary model of the subseafloor is presented that relates microbial diversity to temperature, chemical characteristics of diffuse flow fluids and the degree of mixing with seawater. (C) 2002 Federation of European Microbiological Societies. Published by Elsevier Science B.V. All rights reserved.