The Osmolyte Ties That Bind: Genomic Insights Into Synthesis and Breakdown of Organic Osmolytes in Marine Microbes

The production and consumption of organic matter by marine organisms plays a central role in the carbon cycle. Labile compounds (metabolites) are major currency energetic demands organismal interaction, but these remain elusive because their rapid turnover concomitant minuscule concentrations dissolved pool. Organic osmolytes group small metabolites synthesized at high intracellular (mM) to regulate cellular osmolarity have potential be released as abundant substrates. Osmolytes may represent an essential exchange among heterotrophic prokaryotes primary secondary producers food webs. For example, well-known metabolite dimethylsulfoniopropionate (DMSP) is used osmolyte some phytoplankton can subsequently metabolized 60% bacterial community, supplying up 13% demand 100% sulfur demand. While been studied for decades, our understanding cycling significance within microbial communities still far from comprehensive. Here, we surveyed genes responsible synthesis, breakdown, transport 14 key osmolytes. We systematically searched across genomes ( n = 897) protistan transcriptomes 652) using homologous protein profiles investigate metabolisms. Using pattern gene presence absence, infer metabolic microbes interact with each osmolyte. Specifically, identify: (1) complete pathways synthesis both prokaryotic eukaryotic microbes, (2) capable transporting lacking and/or breakdown pathways, (3) whose appears specialized limited subset organisms. analysis clearly demonstrates that loop has genetic actively recycle this function significant source nutrients through diverse groups significantly contribute labile carbon.