Decoding of genomic determinants of nitric oxide biosynthesis in mammals and microorganisms has created a base for the systemic analysis of genetic conditionality of this process in lactobacilli. In the present work computer screening of synthetic ways leading to NO formation has been held in order to prove nitric oxide production through NO-synthase system in Lactobacillus plantarum. By the use of EPR spectroscopy experimental evidence of nitric oxide enzymatic generation from L-arginine, not nitrite, has been received. With a concrete example of NO-synthase from L. plantarum it is shown, that registered functional activity of proteins is a consequence of complex transformation of their genetic program into a real catalytic function under certain conditions.