GLYCOTHIOHEXIDES, NOVEL ANTIBIOTICS PRODUCED BY "Sebekia" sp. LL-14E605

I. TAXONOMY, FERMENTATION AND BIOLOGICAL EVALUATION

Abstract

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-14E605 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 α demonstrated excellent in vitro activity against Gram-positive bacteria with MICs of 0.03 to 0.06μ/ml against methicillin-resistant Staphylococcus aureus and vancomycin-resistant Enterococcus faecalis. However, glycothiohexide α failed to protect mice against a lethal challenge with Staphylococcus aureus Smith unless it was administered prior to challenge.