Linoleic acid functions as a quorum‐sensing molecule in Monascus purpureus–Saccharomyces cerevisiae co‐culture

Abstract When Monascus purpureus was co‐cultured with Saccharomyces cerevisiae , we noted significant changes in the secondary metabolism and morphological development of Monascus . In yeast co‐culture, although the pH was not different from that of a control, the Monascus mycelial biomass increased during fermentation, and the Monacolin K yield was significantly enhanced (up to 58.87% higher). However, pigment production did not increase. Co‐culture with S. cerevisiae significantly increased the expression levels of genes related to Monacolin K production ( mokA – mokI ), especially mokE , mokF , and mokG . Linoleic acid, that has been implicated in playing a regulating role in the secondary metabolism and morphology of Monascus , was hypothesized to be the effector. Linoleic acid was detected in the co‐culture, and its levels changed during fermentation. Addition of linoleic acid increased Monacolin K production and caused similar morphological changes in Monascus spores and mycelia. Exogenous linoleic acid also significantly upregulated the transcription levels of all nine genes involved in the biosynthesis of Monacolin K (up to 69.50% higher), consistent with the enhanced Monacolin K yield. Taken together, our results showed the effect of S. cerevisiae co‐culture on M. purpureus and suggested linoleic acid as a specific quorum‐sensing molecule in Saccharomyces – Monascus co‐culture.