Project description:Prochlorococcus marinus is a highly abundant picocyanobacterium in Earth’s oceans and therefore a significant contributor to global primary production. This organism exists as different ecotypes, each occupying particular environments in the euphotic zone that differ in both solar penetration and nutrient levels. The ecotypes analysed here were isolated from depths of 5 m (MED4), 135 m (MIT9313) and 120 m (SS120) and cultured at low illumination. MED4, adapted to high light levels closer to the surface, was compared at both low and high illumination. In contrast to other cyanobacteria such as Synechocystis with a dominance of photosystem I (PSI) over photosystem II (PSII) complexes in the thylakoid membranes, MED4 and MIT9313 showed about equal levels. In MED4, the relative levels were almost the same in both the high and low light cultures. SS120 thylakoids contained a lower cytochrome b6f content and around two-fold more PSII than PSI. Additionally a significantly higher abundance of light-harvesting Pcb proteins was found in SS120 than the other ecotypes. This proteomic comparison was employed in conjunction with thylakoid membrane AFM imaging to rationalize the strategies these ecotypes use to survive in the different oceanic environments.
Project description: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.
Project description: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.