[Production of vitamin B 12 by a blue-green alga].

In this study, we have been able to demonstrate the production and liberation of vitamin B12 (up to 16.5 pg/ml after 31 days of growth) by a blue green alga. Anabaena flos-aquae, in non-axenic and axenic cultures. This finding has a relevant ecological significance since it shows that, like bacteria, blue green algae may play a role as producers of vitamin B12.