Enhancement of Monascus Azaphilone Pigments Production Without Citrinin Contamination by Targeting Overexpression of Histone Acetyltransferase MrEsa1 and Deletion of Polyketide Synthase PksCT

Monascus spp. are renowned for producing valuable Monascus azaphilone pigments (MonAzPs), yet their biosynthesis is intrinsically linked to the co-production of the mycotoxin citrinin, posing a significant safety challenge and limiting industrial application. Conventional approaches to disrupt citrinin synthesis often inadvertently reduce MonAzPs yield. To circumvent this limitation, we employed a dual-targeting strategy in Monascus ruber. In this study, we selected the mresa1-overexpressed strain—which can produce more MonAzPs and citrinin—as wild strain to construct a pksCT-deleted strain and explore whether pksCT deletion can affect the enhancement of MonAzPs caused by MrEsa1 overexpression. The results showed that the growth, development, and production of MonAzPs in △pksCT-M7::PtrpC-mresa1 were comparable to those in M7::PtrpC-mresa1, showing accelerated growth and higher MonAzPs yields than in M7. In addition, the relative expression levels of genes involved in MonAzPs synthesis in △pksCT-M7::PtrpC-mresa1 and M7::PtrpC-mresa1 showed the same trend compared with M7, indicating that MrEsa1 overexpression can resist the reduction in MonAzPs caused by pksCT deletion. This study establishes a novel and effective paradigm for decoupling desirable metabolite production from toxin synthesis in fungi, providing a strategic framework for the safe and enhanced production of MonAzPs.