ISOLATION OF A NEW EPIDERMIN VARIANT FROM 2 STRAINS OF STAPHYLOCOCCUS-EPIDERMIDIS - FREQUENCY OF LANTIBIOTIC PRODUCTION IN COAGULASE-NEGATIVE STAPHYLOCOCCI

A novel lantibiotic identified during the screening of 187 coagulase-n egative staphylococci, has been structurally characterised. (Val1, Leu 6)-epidermin was purified from culture supernatants of two Staphylococ cus epidermidis strains, BN-V1 and BN-V301 following successive separa tion by adsorption, cation exchange and C18 reversed-phase chromatogra phy. Separation of the purified peptides by SDS-polyacrylamide gel ele ctrophoresis suggested a molecular mass of ca. 2000 Da and electrospra y mass spectrometry subsequently demonstrated that both peptides had a mass of 2151 Da; a mass which is different from that of all previousl y described antimicrobial peptides. Amino acid analysis showed that bo th peptides contained lanthionine and were very similar to epidermin, while automated N-terminal sequencing by Edman degradation confirmed t he identity of the two peptides as a natural variant of the antimicrob ial lantibiotic epidermin, and demonstrated the conservative amino aci d exchanges in positions one and six.