Taxonomic and functional analysis of microbial mat communities of Mariana region hydrothermal vents

Subsurface-derived hydrothermal fluid releases an abundance of reduced compounds (H2S, Fe2+, Mn2+), which are converted by lithotrophic microbial primary producers into an otherwise unavailable form of energy and carbon for heterotrophs (Nakagawa & Takai, 2008). Differential magma sources that feed the Mariana hydrothermal vents result in heterogeneous chemical composition of the vent fluids. Coupled with the ephemeral nature of vents, the Mariana vents host diverse and metabolically versatile microbial communities (Davis & Moyer, 2008). Microbial communities from these vents with high ferrous iron (Fe2+) concentration are dominated by Zetaproteobacteria (Hager et al., 2016). Within the vast phylum Proteobacteria, Zetaproteobacteria are lithotrophic Fe-oxidizing bacteria (FeOB) that obtain energy by transferring an extracellular electron from Fe2+ into the cell to be used in ATP production (Barco et al., 2015). An outer membrane cytochrome c (cyc2), predicted to play a role as the dedicated redox-active protein involved in extracellular electron transfer (EET), was highly expressed in a cultivated Zetaproteobacterial strain Mariprofundus PV-1. Using quantitative polymerase chain reaction (qPCR), determining the abundance of Zetaproteobacteria cyc2 of iron-rich microbial communities from the Mariana vents will further our understanding of the functional role and impact of the microbial primary producers on lithotrophic habitats