Synthesis of nitric oxide from the two equivalent guanidino nitrogens of L-arginine by Lactobacillus fermentum.

Ten strains of Lactobacillus fermentum that differed in origin converted metmyoglobin to nitrosylmyoglobin [a pentacoordinate nitric oxide (NO) complex of Fe(II) myoglobin] in MRS broth at pH 4.3. Of the 10 strains, L. fermentum IFO 3956 possessed the strongest capacity to convert metmyoglobin to nitrosylmyoglobin. This strain synthesizes NO enzymatically from the two equivalent guanidino nitrogens of L-arginine. To our knowledge, this demonstrates for the first time the production of NO synthesized from the guanidino nitrogens of L-arginine by lactic acid bacteria. IFO 3956 may possess a bacterial NO synthase.