Lactobacillus reuteriCRL1098 Produces Cobalamin

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Abstract
We found thatLactobacillus reuteriCRL1098, a lactic acid bacterium isolated from sourdough, is able to produce cobalamin. The sugar-glycerol cofermentation in vitamin B12-free medium showed that this strain was able to reduce glycerol through a well-known cobalamin-dependent reaction with the formation of 1,3-propanediol as a final product. The cell extract ofL. reutericorrected the coenzyme B12requirement ofLactobacillus delbrueckiisubsp.lactisATCC 7830 and allowed the growth ofSalmonella entericaserovar Typhimurium (metE cbiB) andEscherichia coli(metE) in minimal medium. Preliminary genetic studies of cobalamin biosynthesis genes fromL. reuteriallowed the identification ofcobgenes which encode the CobA, CbiJ, and CbiK enzymes involved in the cobalamin pathway. The cobamide produced byL. reuteri, isolated in its cyanide form by using reverse-phase high-pressure liquid chromatography, showed a UV-visible spectrum identical to that of standard cyanocobalamin (vitamin B12).