Abstract
A microbiological assay method of vitamins in the sample containing streptomycin and dihydrostreptomycin was studied. The growth of Lactobacillus and Streptococcus used for vitamin assay, was inhibited by the existence of streptomycin and dihydrostreptomycin in relatively low concentration. Since these antibiotics are degraded with acid treatment, acid stable vitamins such as biotin and nicotinic acid are easily determined microbiologically after acid treatment. Acid stable vitamins such as pantothenic and folic acid, however, can not be assayed by this means. This paper is concerned with the microbiological assay of the latter, using antibiotic resistant Lactobacilli, which were isolated by means of successive transfer in media containing graded amounts of dihydrostreptomycin. The growth of the resistant strain was not inhibited by the presence of 1000μg/ml of streptomycin or dihydrostreptomycin, and moreover the pantothenic acid requirement of resistant strain of L. arabinosus and the folic acid requirement of resistant strain of St. faecalis were the same with that of each parent. It is preferable to use dihydrostreptomycin resistant Lactobacilli for determination of pantothenic and folic acid in the urine, excreted after the streptomycin or dihydrostreptomycin doses.
