Glycothiohexides, novel antibiotics produced by sebekia sp. LL-14E605. I: 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-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.