Effect of γ-Heptalactone on the Morphology and Production of Monascus Pigments and Monacolin K in Monascus purpureus

Monascus is used widely in Asian countries and produces various biologically active metabolites, such as Monascus pigments (MPs) and monacolin K (MK). In this study, the effect of gamma-heptalactone on secondary metabolites and mycelial growth during Monascus purpureus M1 fermentation was investigated. After the addition of 50 mu M gamma-heptalactone, the yields of MPs (yellow, orange, and red) reached maxima, increased by 115.70, 141.52, and 100.88%, respectively. The 25 mu M gamma-heptalactone groups showed the highest yield of MK was increased by 62.38% compared with that of the control. Gene expression analysis showed that the relative expression levels of MPs synthesis genes (MpPKS5, MpFasA2, mppB, mppC, mppD, mppG, mpp7, and mppR1/R2) were significantly upregulated after gamma-heptalactone treatment. The relative expression levels of MK synthesis genes (mokA, mokC, mokE, mokH, and mokI) were significantly affected. The mycelium samples treated with gamma-heptalactone exhibited more folds and swelling than that in the samples of the control group. This study confirmed that the addition of gamma-heptalactone has the potential to induce yields of MPs and MK, and promote the expression of biosynthesis genes, which may be related to the transformation of mycelial morphology in M. purpureus.

Automated summary

This study investigated the effect of gamma-heptalactone on secondary metabolites and mycelial growth during Monascus purpureus M1 fermentation. The addition of gamma-heptalactone resulted in increased yields of Monascus pigments (MPs) and monacolin K (MK), as well as upregulated expression of biosynthesis genes. Moreover, gamma-heptalactone treatment caused morphological changes in the mycelium of Monascus purpureus.