Vertical Metabolic Activity and Community Structure of Prokaryotes in the Kermadec and Diamantina Trenches

The composition and distribution of prokaryotes in the water columns and benthic boundary layers of the Kermadec and Diamantina Trenches were investigated using high-throughput sequencing and quantitative PCR, together with the Biolog EcoplateTM microplates culture to analyze the microbial metabolic activity. We found that Alphaproteobacteria and Gammaproteobacteria dominating in the water columns and benthic boundary layers of the Kermadec and the Diamantina Trench. microbial communities in the WC, higher similarities were observed between the Kermadec and the Diamantina Trench. These findings suggest similar hadal-associated taxa were present in multiple trenches, potentially transported by deep-ocean currents.The carbohydrates and polymers as the major carbon sources, and phenolic acids were preferentially used by microbial community in the WC and BBL in the Kermadec Trench, respectively; while the phenolic acids were very little used in the WC and BBL in the Diamantina Trench. This could potentially be attributed to the metabolic capabilities of attached microbial groups in different trenches, and reflected the initial preference of the carbon source by the natural microbes in the vertical scale of different trenches.