Staphylococcus capitis strain producing dual bacteriocins, capidermicin and micrococcin P1, shows broad-spectrum antimicrobial activity

Antimicrobial-resistant bacteria have become a global concern, necessitating the development of novel antimicrobial agents. Bacteriocins, antimicrobial peptides produced by bacteria, are promising candidates. In this study, we screened Staphylococcus capitis isolates to identify bacteriocins effective against methicillin-resistant Staphylococcus aureus (MRSA). We discovered that one strain, HBC3, exhibited strong activity against Gram-positive bacteria, including MRSA. Genome analysis revealed a unique plasmid encoding two bacteriocin synthesis genes: capidermicin, a class II bacteriocin, and micrococcin P1 (MP1), a thiopeptide. MP1 was first identified in S. capitis. Loss of the plasmid abolished the antibacterial activity. We purified both peptides and evaluated their spectrum of activity. MP1 showed broad activity, especially against Gram-positive cocci, whereas capidermicin was active mainly against Gram-positive rods. These findings demonstrate that S. capitis HBC3 harbors a plasmid encoding two distinct bacteriocins with complementary antibacterial spectra, highlighting the cooperative potential of bacteriocins in combating resistant bacteria.