Abstract
The effects were examined of adding various nucleic acid derivatives to skim milk on the acid production of lactic acid bacteria. The bacteria used were 9 strains of Lactobacillus, 2 strains of Lactococcus, and one strain of Streptococcus.
Purine-base derivatives (50 mg each) were individually added to 100 ml of skim milk. The effects of these additions on acid production were different among the strains of lactic acid bacteria. Mainly based on the adenine effects, the strains could be classified into 4 groups as follows : growp A, stimulated by adenine and/or its related substances (2 strains of Lactobacillus); group B, stimulated by purine-base derivatives but not by adenine (3 strains of Lactobacillus); group C, inhibited by adenine and 5′-adenylic acid (4 strains of Lactobacillus); and group D, barely stimulated or inhibited by adenine and other purine-base derivatives (the 3 strains of Lactococcus and Streptococcus).
Purine-base derivatives (0.5-50 mg each) were then individually added to 100 ml of skim milk, and their effects on acid production were investigated with 3 strains of Lactobacillus, one of each belonging to groups A, B and C. The added amounts which stimulated or inhibited acid production were studied for each strain.
