Enhancement of natamycin production in Streptomyces gilvosporeus through heavy ion beam mutagenesis and global transcription machinery engineering.

Abstract

Natamycin is an antifungal agent produced by Streptomyces and is widely used in food, pharmaceuticals, and other fields. However, the low production of natamycin limits its application in various fields, making it crucial to enhance the biosynthetic capacity of natamycin-producing strains. In this study, Streptomyces gilvosporeus ATCC 13326 was used to construct a chassis for the efficient production of natamycin through strain engineering. A mutant strain S. gilvosporeus Z1403 with a titer of 1.7 g·L^-1 was obtained by heavy ion beam radiation and LiCl resistance screening, 70.0 % higher than that of the wild-type strain S. gilvosporeus ATCC 13326. Subsequently, transcription factor screening identified whiG as a key regulator of natamycin biosynthesis. Targeting whiG via global transcription machinery engineering further enhanced natamycin production of S. gilvosporeus Z1403. Finally, the high-production mutant strain EP-whiG was obtained with a titer of 2.2 g·L^-1, 29.4 % and 120.0 % higher than that of the parent strain S. gilvosporeus Z1403 and the wild-type strain, respectively. S. gilvosporeus EP-whiG achieved a natamycin production of 13.1 g·L^-1 in a 5-L bioreactor within 120 h by fed-batch fermentation, which was 61.7 % higher than that of the wild-type strain. These results suggest that combining heavy ion beam mutagenesis with global transcription machinery engineering is an effective strategy for strain improvement, laying a theoretical foundation for enhancing the production of secondary metabolites in Streptomyces.