Efficacy of nanoparticle encapsulation on suppressing oxidation and enhancing antifungal activity of cyclic lipopeptides produced by Bacillus subtilis

This study examined the storage instability of cyclic lipopeptides (CLs) extracted from Bacillus subtilis culture; CLs were easily oxidized and therefore quickly lost antifungal activity during storage. Solid lipid nanoparticle (SLN) encapsulation effectively suppressed the oxidation and prolonged and enhanced the antifungal efficacy of CLs through controlled release. Thermal gravimetric analysis, X-ray diffraction, and Fourier transform infrared spectroscopy revealed that hydrophobic interactions between the fatty acid moieties of CLs and SLNs fortified the crystal structure of the CL-SLN complex, thereby improving the storage stability of the encapsulated CLs. Furthermore, the encapsulated CLs also demonstrated more potent antifungal activity than free CLs in damaging fungal cellular membranes, affecting the growth of hyphae and spores, and decreasing ochratoxin A levels. SLN encapsulation is an effective method to protect and improve the function of CLs.