GLYCOTHIOHEXIDES, NOVEL ANTIBIOTICS PRODUCED BY SEBEKIA SP LL-14E605 .1. TAXONOMY, FERMENTATION AND BIOLOGICAL EVALUATION

The new glycothiohexide antibiotics, which are related to nosiheptide, were identified in fermentations of an actinomycete belonging to the genus ''Sebekia''. Strain LL-14E605 was classified as a ''Sebekia'' based on the presence of both mesodiaminopimelic acid and madurose in the cell wall and the presence of pseudosporangia encasing the spores. Culture LL-14B605 was successfully fermented in 10 to 3,000 liters of a complex medium. Antibiotic activity closely followed cell mass accumulation and usually peaked after 4 to 5 days of incubation. Glycothiohexide alpha demonstrated excellent in vitro activity against Gram-positive bacteria with MICs of 0.03 to 0.06 mu g/ml against methicillin-resistant Staphylococcus aureus and vancomycin-resistant Enterococcus faecalis. However, glycothiohexide alpha failed to protect mice against a lethal challenge with Staphylococcus aureus Smith unless it was administered prior to challenge.