Improving the yield of Monacolin K in solid-state fermentation of Monascus purpureus H164 based on fermentation...

Monacolin K (MK), as a secondary metabolite of Monascus, has potential cholesterol-lowering and lipid-lowering effects. To enhance MK production, a systematic screening and optimization of the solid-state fermentation (SSF) bioprocess of Monascus purpureus (M. purpureus) H164 was conducted. Initially, solid fermentation substrates were screened, and japonica rice was identified as the optimal substrate, yielding an MK production of 7.69 mg/g. Based on this, exogenous additives and key fermentation parameters were further screened using single-factor experiments, followed by response surface optimization employing a Box-Behnken design (BBD). According to the screening and optimization results, the addition of 4% burdock fructooligosaccharide (BFO) significantly promoted the MK synthesis in M. purpureus H164 on japonica rice solid culture substrate, resulting in the MK yield of 49.26 mg/g, representing a 6.4-fold increase compared with the original MK production. Furthermore, under the optimized conditions, the expression levels of key genes involved in the MK biosynthetic pathway (mokA, mokB, mokF, mokH, and mokI) were analyzed using real-time quantitative PCR (RT-qPCR). The results indicated that the expression of key genes associated with MK biosynthesis was significantly up-regulated following BFO addition. Overall, these findings provide insights into enhancing MK production in SSF and elucidate the regulatory effect of BFO on MK biosynthesis in strain H164.