Dissolved organic matter released by two marine heterotrophic bacterial strains and its bioavailability for natural prokaryotic communities

Marine heterotrophic prokaryotes (HP) play a key role in organic matter processing the ocean; however, view of HP as dissolved (DOM) sources remains underexplored. In this study, we quantified and optically characterized DOM produced by two single marine bacterial strains. We then tested availability these to situ Mediterranean Sea communities. Two strains were used: Photobacterium angustum (a copiotrophic gammaproteobacterium) Sphingopyxis alaskensis (an oligotrophic alphaproteobacterium). When cultivated on glucose sole carbon source, released from 7% 23% initial derived (B-DOM), quality which (as enrichment humic or protein-like substances) differed between B-DOM induced significant growth consumption natural communities, suggesting that it was partly labile. However, consistently promoted lower prokaryotic efficiencies than DOM. addition, changed exoenzymatic activities, enhancing aminopeptidase activity when degrading P. DOM, alkaline phosphatase using S. differences diversity composition. affects metabolism diversity, thus changing pathways for cycling (e.g. respiration over biomass production) ocean.