Role of reduced sulfur compounds in nutrition of Propionibacterium acnes.

In a study of the nutritional requirements of Propionibacterium acnes, acid hydrolyzed casein was shown to be the preferred nitrogen source in a glycerol-salts medium. Of 22 individual amino acids tested, only cysteine supported growth in the glycerol-salts medium. This indicated a requirement not only for amino nitrogen but also for reduced sulfur. In the presence of an auxiliary nitrogen source, thioglycolate or thiosulfate could replace sulfur-containing amino acids. The apparent requirement of P. acnes for reduced sulfur possibly could be satisfied in vivo by the constant availability of this substance in the form of sulfhydryl groups in the sebaceous follicle during keratinization. The relationship between P. acnes and its nutritional substrate may give this organism a selective advantage to exist in this ecological niche.