Biogeography and biodiversity in sulfide structures of active and inactive vents at deep-sea hydrothermal fields of the Southern Mariana Trough.

The abundance, diversity, activity, and composition of microbial communities in sulfide structures both of active and inactive vents were investigated by culture-independent methods. These sulfide structures were collected at four hydrothermal fields, both on- and off-axis of the back-arc spreading center of the Southern Mariana Trough. The microbial abundance and activity in the samples were determined by analyzing total organic content, enzymatic activity, and copy number of the 16S rRNA gene.

Microbial communities in iron-silica-rich microbial mats at deep-sea hydrothermal fields of the Southern Mariana Trough.

The abundance, diversity and composition of bacterial and archaeal communities in the microbial mats at deep-sea hydrothermal fields were investigated, using culture-independent 16S rRNA and functional gene analyses combined with mineralogical analysis. Microbial mats were collected at two hydrothermal areas on the ridge of the back-arc spreading centre in the Southern Mariana Trough. Scanning electron microscope and energy dispersive X-ray spectroscopic (SEM-EDS) analyses revealed that the mats were mainly composed of amorphous silica and contained numerous filamentous structures of iron hydroxides.