Effects of pigment and citrinin biosynthesis on the metabolism and morphology of Monascus purpureus in submerged fermentation

The effects of the secondary metabolite biosynthesis on the metabolism and morphology of the Monascus purpureus were investigated in this study. Hypha and septum length became longer after deletion of genes pig R and pks CT in M. purpureus LQ-6 by Agrobacterium tumefaciens -mediated transformation technology, highly branched hyphae, much smaller and freely dispersed mycelial pellets were observed in M. purpureus . Compared with that in the wild-type, the level of intracellular NADH and NADPH was almost constant in M. purpureus Δ pig R at 4 days, but the NADH and NADPH levels decreased by 1.58-fold and 3.71-fold in M. purpureus Δ pks CT. The present study can not only provide a kind of strategy to improve the Monascus pigments production, but also provide theoretical support for the further study of relationship between the secondary metabolites, metabolism and morphological change.