Staphylococcus epidermidis enables Cutibacterium acnes to form biofilms under aerobic conditions

Staphylococcus epidermidis and Cutibacterium acnes are among the most abundant members of the human skin microbiome. Both species are associated with skin health and disease. Although skin microbes typically grow in surface-associated biofilms, few studies on the interaction between S. epidermidis and C. acnes in biofilms have been reported. In the present study we measured the ability of S. epidermidis and C. acnes, either individually or jointly, to form biofilms in glass culture tubes. Since S. epidermidis is a facultative anaerobe and C. acnes is an aerotolerant anaerobe, tubes were incubated both aerobically and anaerobically to assess the role of atmosphere in biofilm formation. When cultured individually, we found that S. epidermidis formed biofilms under both aerobic and anaerobic conditions, whereas C. acnes formed biofilms only under aerobic conditions. When co-cultured, the presence of C. acnes had no effect on S. epidermidis biofilm formation under either aerobic or anaerobic conditions. However, the presence of S. epidermidis significantly enhanced the growth of C. acnes biofilms under anaerobic conditions and enabled C. acnes to form biofilms under aerobic conditions. This finding may be clinically relevant to the interaction between S. epidermidis and C. acnes on human skin.