Both strains produced a potent anti-MRSA compound characterized by a major LCMS peak of 1514 Da proposed at that time as a new thiazolyl peptide [21] that we confirmed to correspond to kocurin (data not shown). In contrast to the Kocuria and Micrococcus strains, both strains of Arthrobacter produce kocurin in the medium CGY [21], a medium also used in our study without success.