Preliminary Study On The Mechanism Of Monacolin K By Monascus Fuliginosus Sato

Monacolin K,a secondary metabolite synthesized by polyketide synthases in red yeast rice,is widely used as an anti-hypercholesterolemia medicine.Further more,Monacolin K(acid form)has highly effect of preventing cardiovascular and cerebrovascular diseases with lower side effects.However,the low production of Monacolin K and the existence of citrinin have been greatly limiting the development of red yeast rice products.This paper aims at investigating the influence of temperature and metal ions on Monacolin K ratio,the production of Monacolin K and citrinin,then analyzing the expression of Monacolin K biosynthesis genes with Real-Time PCR characterizes the influence of temperature and the addition of metal iron on Monacolin K biosynthesis.This study provided a theoretical basis for the genetic engineering bacteria construction of high-yield monacolin K(acid form)without citrinin.By comparing the effect of different temperature on Monacolin K(acid form)production,we found that the maximal production of Monacolin K(acid form)(6.333mg/g dry weight,80.9%)was seen on the 26th day in 25?.And under 30?,the maximal production of Monacolin K(acid form)(4.620mg/g dry weight,81.4%)was seen on the 23th day while under 35?,the maximal production of Monacolin K(acid form)(4.855mg/g dry weight,93.5%)was seen on the 23th day.The addition of ZnSO4,MnSO4 and MgSO4 in the solid medium can effectively change the production of Monacolin K.When the ZnSO4 concentration is up to 0.1%,the production of Monacolin K(acid form)will be highly increased and the maximal production is up to 6.415mg/g dry weight which contributed to 80.9%of total monacolins.And when the MgSO4 concentration is up to 0.75%,the maximal of production is up to 6.545mg/g dry weight which contributed to 94.69%of total Moncolin K while when the MnSO4 concentration is up to 0.3%,the maximal production is up to 7.77mg/g dry weight which contributed to 98.2%of total monacolins.Furthermore,on the basis of Box-Behnken experimental design,the optimal extraction condition of the maximal of production of Moncolin K and biomass of Monascua is When the concentration of ZnSO4 is up to 0.1%,MnSO4 to 0.3%and MgSO4 to 0.75%.To characterize the influence of temperature and the addition of metal iron on Monacolin K biosynthesis,we monitored the expression of the nine genes in Monascus CG-6 at 25?,30? and 35? by Real-Time PCR analysis.To complete this experiment,we used solid and chemical defined medium covered with cellophane,then we had some conclusions.low temperature increases the expression level of mokD,mokG and mokI;The addition of Zn2+in medium has significant influence to the expression level of mokH and mokE.the high dose of Zn2+will increases the expression level of mokH,while reduces the expression level of mokE.The detection citrinin in samples is very low or undetectable,so Monascus CG-6 can be used for industrial fermentation as a safety strain with highly production Monacolin K and extremely lowly citrinin.