FIELD: genetic engineering, biochemistry, microbiology. SUBSTANCE: invention relates to genetically recombinant bacterial strains. Method involves isolation of gene sequence from bacterial host encoding D- lactate dehydrogenase and the modified sequence is obtained. Then donor bacterial strain containing conjugative vector that in not able to replicate in the host bacterial strain is selected. The modified sequence is ligated into this vector, prepared construction is incorporated into donor bacterial strain and donor microorganisms where the parent vector and conjugative vector passed recombination are selected. Using conjugation mechanism the conjugative vector is transferred into bacterial host-strain. Strains where sequence encoding enzyme D-lactate dehydrogenase is replaced with the modified sequence and DNA sequence of conjugative vector is removed from genome are selected. Strains Lactobacillus johnsonii CNCM 1-1851 and 1-1852 are producers of L-(+)-lactic acid and used for pre- paring dairy foodstuffs. Invention ensures to obtain bacterial strains with ability to survive in intestine, attach to intestine cells and carry out immunomodulation and producing L-(+)-lactic acid only. EFFECT: improved bacterial strain preparing method, valuable properties. 6 cl, 4 dwg, 4 ex
