Identification of Prochlorococcus

Free-living single celled organisms <1 µm in diameter. Possess appressed photosynthetic thylakoids adjacent to their gram -ve cell walls. Characteristic pigment composition: divinyl chlorophyll a and b; The ratios of dvchl a and b differ between strains and light intensities; dvchl a and b absorb efficiently at wavelengths available in the blue-light dominated deep euphotic zone of the open ocean.