Abstract
The nutritional requirement of L. bulgaricus B-1 strain have been studied. By the culture of the strain in a modified Thompson's medium, it was found that the strain possessed very complex requirements of growth factors. The strain required L-tyrosine, L-cystine, nicotinic acid, riboflavin, enzymatic digest of casein, and Tween 80 in addition to pantethine and pantothenate.
Elongation of the strain was found in the absence of vitamin B12 and folic acid, but it could be prevented by addition of vitamin B12 and folic acid.
It was of interest that the mixture of the enzymatic digest of casein and Tween 80 became toxic to the strain at higher concentrations, though each substance stimulated the growth of the strain in an amount up to 100 and 50mg per 100ml of the basal medium, respectively. The strain was also found to be useful for the microbiological assay of nicotinic acid, nicotinamide, enzymatic digest of casein, and Tween 80 in addition to pantethine.
