Lactobacillus reuteri is a single cell bacterium which is a part of the gastrointestinal system of humans and other higher animals. It helps humans lower their cholesterol levels and produces a broad spectrum antibacterial agent called reuterin.
Cobalamin (one of several forms of vitamin B-12) is necessary for some enzyme reactions in humans, but since one can’t synthesize it, one must consume it. L. reuteri produces cobalamin, which is needed to metabolize glycerol. The present study evaluated the ability of L. reuteri to ferment glycerol in an environment free of vitamin B-12. The researchers proved that L. reuteri can metabolize glycerol without any external source of cobalamin, and addition of cobalamin to the mixture failed to speed up the reaction.
Interestingly, Lactobacillus delbrueckii, obtained from sourdough, needs external cobalamin. L. delbrueckii was able to grow in a vitamin B-12 environment only after L. reuteri was added to the mix to provide cobalamin. Results were further confirmed by testing of two bacteria, Salmonella serovar and Escherichia coli.
One drawback to L. reuteri is that the cobalamin is not released from the living bacteria. It would be useful to find a mutant form of the bacteria which dies and decays in the acid of the stomach (where vitamin B-12 is usually absorbed).
CONCLUSION: L. reuteri “might be a good candidate to increase the cobalamin content in fermented food.”
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