Intracellular and extracellular metabolites from three strains of Prochlorococcus

Prochlorococcus is an abundant, cosmopolitan, marine cyanobacterium with ecotypes that vary temporally and spatially across oligotrophic regions of the global ocean. This group of organisms can serve as a model system to understand the accumulation of organic compounds synthesized by primary producers in marine ecosystems. We applied targeted metabolomics to three axenic cultures of strains that span the Prochlorococcus phylogeny: a high-light adapted HLII-clade strain, a low-light adapted LLI-clade strain, and a low-light adapted LLIV-clade strain. Intracellular metabolites were extracted from cells captured in exponential growth and extracellular metabolites were adsorbed, from the same samples, to solid-phase extraction resin. Both pools were quantified using a triple quadrupole mass spectrometer. The resulting data reveal intraspecific differences in metabolites that provide clues about the selective pressures shaping the meta-metabolism of the Prochlorococcus collective, and its interactions with the surrounding microbes that depend on them.