MrGcn5 is required for the mycotoxin production, sexual and asexual development in Monascus ruber

Abstract Hongqu is a fermented product of Monascus species, which is widely used as food or food additives in Southeast Asian countries. The contamination of citrinin in Hongqu has caused controversy about its safety. So control of citrinin has always been an important issue of Hongqu products. In current study, we isolated a putative histone acetyltransferase named MrGcn5 and explored its regulatory function on citrinin production. The results showed the citrinin content of MrGcn5 null strain dramatically reduced in the late growth period. Even the citrinin content was as low as 21 % of the wild-type strain, and RT-qPCR experiment suggested that the expression level of genes involving in citrinin synthesis was significantly attenuated in MrGcn5 null strain. With regard to the asexual and sexual development, the conidia germination rate was significantly accelerated in MrGcn5 null strain in the vegetative growth phase, but the number of ascospores was 41.9 % less than the wild-type strain. RT-qPCR revealed the expression level of the homologs to flbA-flbE, fluG and wetA in Aspergillus had changed to some extent in MrGcn5 null strain. Meanwhile, there was no significant effects on the growth, nutrition adaption and Monascus azaphilone pigments production. Taken together, these characteristics of MrGcn5 make it very suitable for targeted improvement to reduce citrinin production in fermentation process.