Efficient Control of Molds Contamination Through Gene Cluster Regulation and Enzyme Rational Design of Iturin a

Abstract

Molds are prevalent environmental contaminants, posing significant risks to both human and animal health. Iturin A, known for its potent antifungal activity, offers a potential solution for control of molds contamination. In this study, a novel strain Bacillus velezensis ZD122 was successfully screened for iturin A production and mold control, and the gene cluster ituDABC was identified to be responsible for iturin A synthesis by genomic analysis. Through inserting a promoter in front of ituA and ituD, the production of iturin A were increased by 1.71-fold. Meanwhile, the malonyl-CoA transacylase ItuD was modified by rational design to obtain the beneficial mutant ItuDR117A/C161A, resulting in a 74.36% increase in iturin A yield compared to the control strain. Molecular dynamics simulations further elucidate the potential mechanisms underlying the enhancement of enzyme activity. Through combinatorial expression, the iturin A production of the optimized recombinant strain ZD-P5/pHY-ituDR117A/C161A reached 1.32 g/L. The increased iturin A production significantly enhanced antifungal efficacy against various molds. In summary, this study provides a valuable microbial resource for the production of iturin A, offering efficient strategies for control of the mold contamination.

Keywords: Bacillus velezensis, iturin A, rational design, Molecular modification, antifungal effect