Compositional Characteristics of Lactic Acids Produced by Lactobacillus acidophilus Group Lactic Acid Bacteria

Abstract

The ratio of D-and L-lactic acid produced in media by 39 strains of the L. acidophilus group lactic acid bacteria (A1-A4, B1, and B2 subgroups) was analyzed by high performance liquid chromatography (HPLC). L. acidophilus (A1) and L. Johnsonii (B2) produced the lowest (5 strains average: 41.9%) and the highest (4 strains average: 61.4%) contents of D-lactic acid in MRS broth, respectively. Generally, the most dominant lactic acid (more than 50%) produced by each strain in MRS broth was a D-type isomer, except for the A, subgroup. In L. gasseri DSM 20243T (B1), increases in the sugar content in MRS broth induced both a high production of total lactic acids and a high ratio of D-lactic acid. In skim milk, D-lactic acid decreased by 20-30% in 5 strain types of the L. acidophilus group except L. amylovorus JCM 1126T (A3). By sequentially changing the medium, the content of D-lactic acid in the final MRS broth reverted to almost the same level of that in the initial MRS broth. These results indicated that the ratio of D-lactic acid produced by L. acidophilus group bacteria may be controlled by improving fermentative conditions.