Proteomics and direct Protein-SIF of the bacterial ectosymbionts of the ciliate Kentrophoros sp. H

Kentrophoros ciliates are found worldwide in coastal marine sediment, and have an obligate symbiosis with sulfur-oxidizing Gammaproteobacteria called Candidatus Kentron. The genomes of different Kentron species suggest that they are chemolithoheterotrophs, producing new biomass from organic carbon substrates. We investigated the metaproteome of Kentrophoros sp. H and its symbiont (from two sites in the Mediterranean), to verify that hypothesized pathways of carbon and energy metabolism are indeed expressed, and to estimate the stable isotope fractionation in biomass, which can be a signature of the carbon sources used by the organism.