New antibiotics produced by Bacillus subtilis strains

Two Bacillus subtilis strains isolated from the fruiting body of a basidiomycete fungus Pholiota squarrosa exhibited a broad range of antibacterial activity, including those against methicillin-resistant Staphylococcus aureus INA 00761 (MRSA) and Leuconostoc mesenteroides VKPM B-4177 resistant to glycopeptide antibiotics, as well as antifungal activity. The strains were identified as belonging to the “B. subtilis” complex based on their morphological and physiological characteristics, as well as by sequencing the 16S rRNA gene fragments. Both strains (INA 01085 and INA 01086) produced insignificant amounts of polyene antibiotics (hexaene and pentaene, respectively). Strain INA 01086 also produced a cyclic polypeptide antibiotic containing Asp, Gly, Leu, Pro, Tyr, Thr, Trp, and Phe, while the antibiotic of strain INA 01085 contained, apart from these, two unidentified nonproteinaceous amino acids. Both polypeptide antibiotics were new compounds efficient against gram-positive bacteria and able to override the natural bacterial antibiotic resistance.