Isolation and Characterization of a New Fusaricidin-Type Antibiotic Produced by Paenibacillus bovis sp. nov BD3526.

Paenibacillus bovis sp. nov BD3526, isolated from raw yak (Bos grunniens) milk, was able to produce antibacterial substances against Micrococcus luteus. The antibacterial substances produced by the strain BD3526 in 3% (w/v) wheat bran broth under aerobic conditions were precipitated from the cultivated broth with ammonium sulfate at 60% saturation. Two antibacterial compounds were obtained by Sephadex LH-20 chromatography and semi-preparative reverse-phase high-performance liquid chromatography (Semi-Pre RP-HPLC). The chemical structures of the two antibacterial compounds were further elucidated by means of ultra high-performance liquid chromatography-mass spectrometer/mass spectrometer (UHPLC-MS/MS). One compound, with a molecular mass of 883.56195 Da (M + H)+, was determined to be identical in chemical structure with that of the well-known compound fusaricidin A. The other antimicrobial compound with a molecular mass of 911.59393 Da (M + H)+ was determined to be a derivative of fusaricidin A by tandem mass spectrometry and amino acid composition analysis and was designed as bovisin. Bovisin possessed the stability against acid/alkali, heat and some proteases treatment, the same with the fusaricidin A. However, the minimal inhibition concentration (MIC) of bovisin on the tested indicator including Staphylococcus aureus, Micrococcus luteus, Listeria monocytogenes and Bacillus subtilis were 50, 50, 50, 50 μg/mL, respectively, slightly higher than those of fusaricidin A (6.25, 6.25, 6.25, 12.5 μg/mL), indicating bovisin with a weaker inhibitory activity.