Taxonomic and functional characterization of biofilm samples from two shallow-water hydrothermal vents in Pozzuoli bay

Shallow water hydrothermal vents represent truly peculiar environments, whose geological settings and resulting physico-chemical parameters shape the macro- and micro-flora and fauna. Hydrothermal fluids discharge CO2 in gaseous form (98-99%), with other gases such as H2S, CH4, SO42-, and HF in minimum percentages depending on geological characteristics. These gases are exploited by local microbial communities to fuel their metabolism, thus resulting in primary production that essentially supports biodiversity and trophic webs both on-vent and surrounding off-vent sites. While the geochemistry and ecology of these environments has been widely explored, the microbial diversity remains poorly investigated. This work aims to describe the taxonomic and functional diversity of six biofilm samples collected near two hydrothermal vents sites of Secca delle Fumose, Pozzuoli bay (Campania). Despite being a few tens metres apart these systems have different temperature and chemistry, allowing us to compare taxonomic and functional differences of their microbial communities. We performed shotgun metagenomic sequencing on extracted DNA and taxonomic and functional annotations using the K-base platform. These results confirmed our expectations of significant differences between on-vent microbial assemblages’ characteristics, suggesting that understanding how shallow-water hydrothermal vents sustain microbial diversity patterns and processes might be of great ecological significance, also given increasing evidence of their role in performing significant ecosystem roles for carbon cycling and climate regulation services.