the addition of M. purpureusfermentation filtrate to the medium promoted the growth and caroten-oids biosynthesis of R. mucilaginosa, potentially due to the presence ofmetabolites in M. purpureus fermentation filtrate. Monacolin K, meva-lonic acid and amylase are Monascus metabolites and appear inM. purpureus fermentation filtrate. Monacolin K inhibited the biosyn-thesis of mevalonic acid by blocking access of HMG-CoA to the bindingsite of HMG-CoA reductase