Nutrient Acquisition: The Generation of Bioactive Vitamin B-12 by Microalgae

Many microalgae acquire vitamin B-12 from marine prokaryotes. A new study demonstrates that vitamin B-12 is synthesized by planktonic cyanobacteria as pseudocobalamin, a form not bioactive in microalgae. However, some microalgae can remodel pseudocobalamin to the active cobalamin form, adding complexity to our assessment of active vitamin B-12 in the environment.