Studies of lactic acid bacteria associated with brewery products. IV.—interrelationships in requirements for purines, folic acid and p‐aminobenzoic acid

Of thirty‐four lactic acid bacteria isolated from beer or from growing yeast, seventeen required uracil for growth; none required xanthine. In two cases there is evidence of interconversion of guanine and xanthine, growth failing in the absence of both these purines. The presence or absence of P‐aminobenzoic acid and folic acid has an effect on the purine requirements which varies with different organisms.