Functional interactions among filamentous E psilonproteobacteria and B acteroidetes in a deep‐sea hydrothermal vent biofilm

Abstract

Summary Little is known about how lithoautotrophic primary production is connected to microbial organotrophic consumption in hydrothermal systems. Using a multifaceted approach, we analysed the structure and metabolic capabilities within a biofilm growing on the surface of a black smoker chimney in the L oki's C astle vent field. Imaging revealed the presence of rod‐shaped B acteroidetes growing as ectobionts on long, sheathed microbial filaments (> 100 μm) affiliated with the S ulfurovum genus within E psilonproteobacteria . The filaments were composed of a thick (> 200 nm) stable polysaccharide, representing a substantial fraction of organic carbon produced by primary production. An integrated –omics approach enabled us to assess the metabolic potential and in situ metabolism of individual taxonomic and morphological groups identified by imaging. Specifically, we provide evidence that organotrophic B acteroidetes attach to and glide along the surface of S ulfurovum filaments utilizing organic polymers produced by the lithoautotrophic S ulfurovum . Furthermore, in situ expression of acetyl‐ CoA synthetase by S ulfurovum suggested the ability to assimilate acetate, indicating recycling of organic matter in the biofilm. This study expands our understanding of the lifestyles of E psilonproteobacteria in hydrothermal vents, their metabolic properties and co‐operative interactions in deep‐sea hydrothermal vent food webs.

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