Occurrence of Cobalamin Coenzymes in the Photosynthetic Green Alga,Chlorella vulgaris

To analyze cobalamin metabolism in photosynthetic green algae, the effects of cobalamin on growth of Chlorella vulgaris C-30 were studied and the algal cobalamin contents were assayed. Cobalamin significantly stimulated growth of the Chlorella cells, but biologically inactive cobalamin analogues did not. Chlorella grown in a cobalamin-free medium (control) contained cobalamin coenzymes, 5'-deoxyadenosylcobalamin (7.95 ± 0.31 ng/g wet weight) and methylcobalamin (2.72 ± 0.45 ng/g wet weight), of which the levels were increased significantly in cobalamin-supplemented cells. These results indicate that the alga has ability to take up exogenous cobalamin and synthesize the coenzyme forms.