Effect of γ-butyrolactone, a quorum sensing molecule, on morphology and secondary metabolism in Monascus

Abstract

Monascus is widely used in Asia and produces active metabolites–Monascus pigments and monacolin K. Quorum sensing (QS) regulates mycelial development and secondary metabolism in filamentous fungi; however, QS studies in Monascus are limited. Here, the effect of γ-butyrolactone, a possible QS molecule, on Monascus purpureus was investigated. γ-butyrolactone accelerated cell growth, promoted the synthesis of Monascus pigments and monacolin K, and reduced citrinin synthesis. Scanning electron microscopy showed γ-butyrolactone caused mycelial surface folding and spore pitting. Real-time quantitative PCR revealed γ-butyrolactone upregulated the transcriptional expression level of genes related to morphology and Monascus pigments and monacolin K synthesis and downregulated that related to citrinin synthesis. Overexpression of lip10 affected Monascus growth and morphology and promoted Monascus pigments and monacolin K yields. Transcriptomic analysis showed that the cell growth, membrane, and energy metabolism pathways were the most enriched in γ-butyrolactone-treatment group. γ-butyrolactone functions as a QS molecule in Monascus and significantly affects Monascus morphology and secondary metabolism, possibly by regulating the transcriptional expression of genes relevant to cell development, synthesis of secondary metabolites, and energy metabolism of M. purpureus. This study sheds light on QS in Monascus and provides a possible novel strategy to improve microbiological food quality and safety.