Selective antibacterial action of 2-mercaptoethanol on propionibacteria in skin cultures

2-Mercaptoethanol applied to the surface of agar medium had a selective antibacterial effect on Propionibacterium acnes and Propionibacterium granulosum without interfering with the growth of Peptococcus saccharolyticus or staphylococci in anaerobic cultures of skin or in pure cultures. In aerobic broth culture, 2-mercaptoethanol inhibited aerobes and stimulated anaerobes, consistent with its action as a reducing agent.