Study On The Effect Of Solid-state Fermentation Substrate On Monascus Statin And Pigments Yield

Monascus is a traditional edible and medicinal fungus with a history of nearly 2000 years in China.Monascus produces Lovastatin and Monascus pigments in the fermentation process and other secondary metabolites are beneficial to human body.Lovastatin,also known as Monacolin K,is currently recognized as a cholesterol-lowering active substance in the world.As an edible natural pigment,Monascus pigment has the advantages of strong coloring ability and high safety compared with synthetic pigment.In this study,the solid-state fermentation of Monascus fuliginosus MPs-7 was carried out by respectively adding soybean meal,wheat bran,bean dregs and ripe bean dregs on the basis of rice substrate,then analyzed the yield of Monacolin K and Monascus pigments,and preliminarily studied the mechanism of solid-state fermentation substrate affecting the yield of two metabolites.The results are as follows:When rice was used as substrate for Monascus MPs-7 solid-state fermentation,the yield of fermentation products was low,and there is no any form of Monacolin K was produced,the yield of pigments was high.Four kinds of excipients were added as fermentation substrates to increase the yield of fermentation products and promote the production of Monacolin K,but at the same time inhibit the production of Monascus pigments.Among them,the highest total yield of Monacolin K reaching 3177?g/g fermentation products with adding 15%soybean meal.The inhibition of pigments by adding ripe bean dregs was not significant as that by the other three excipients.Adding wheat bran and bean dregs as excipients,Monacolin K had low yield and significantly inhibited the synthesis of pigments.Therefore,two kinds of excipients,soybean dregs and ripe bean dregs,were screened for further study.It was found that the addition of soybean dregs was more beneficial to the accumulation of Monacolin K than that of ripe bean dregs at the same proportion,but the inhibition of pigment was more significant.In order to balance the production of two metabolites,adding 15%ripe bean dregs as fermentation substrate increased the yield of Monacolin K while producing a certain yield of Monascus pigments,and the cost was lower than that of soybean meal,It is more suitable as an anxiliary substrate to be added to the Monascus solid-state fermentation.Preliminarily studied the mechanism of the effect of excipients on the yield of Monacolin K in solid-state fermentation.Nitrogen content of raw materials in solid-state fermentation substrate was determined.It was found that the increase of nitrogen content in fermentation substrate was beneficial to the accumulation of Monacolin K in a certain range.The phase and content of water in the initial and final stages of fermentation were determined.It was found that the higher the degree of water freedom in the initial stage of fermentation,the more beneficial to the accumulation of Monacolin K.During the process of fermentation,free water was transformed into bound water.And the higher content of bound water in the final stage of fermentation,the more beneficial to the accumulation of Monacolin K,Scanning electron microscopy was used to observe the cross-sectional microstructures of red yeast rice.Compared with the blank control,the amount of mycelium in the samples added with excipients increased significantly,and there was a positive correlation between the amount of mycelium and the accumulation of Monacolin K.