Structural analysis and enhanced production of fusaricidin from Paenibacillus kribbensis CU01 isolated from yellow...

A bacterial strain showing strong antifungal activity was isolated from yellow loess and was identified as Paenibacillus kribbensis CU01. Insoluble mucoidal polymers were separated from M9 culture medium via low-speed centrifugation. Most antifungal activity was associated with substances in the insoluble precipitate, which was purified by reverse phase high performance liquid chromatography. Purified fractions were analyzed using matrix-assisted laser desorption/ionization time-of-flight/time-of-flight mass spectrometry. Two major ion peaks with mass-to-charge ratio values (m/z) at 883.6 and 897.6 were revealed. After alkaline hydrolysis and sequence analysis, two cyclic depsipeptides were identified as, fusaricidin A and fusaricidin B. Their production was significantly increased by the addition of glucose, Fe²⁺ , and Mn²⁺ to M9 medium. Maximum concentrations of produced fusaricidin A and fusaricidin B at flask-scale comprised 460 mg L^-1 and 118 mg L^-1 , respectively: the highest production concentrations yet reported in the literature. This demonstrates that P. kribbensis CU01 has enormous commercial potential for the mass production of fusaricidin.