Screening,Mutagenesis And Fermentation Process Optimization Of Monascus For Lovastatin Production

Monascus has been applied for more than one thousand years in China,it has always been taken as a magical microorganism for traditional foods' processing.In 1975,Japanese scholar Endo Akira found that lovastatin was contained in fermentation broth of monascus,this interesting finding arose a monascus studying boom among scholars at home and abroad.Lovastatin,a secondary metabolite of monascus,can competitively inhibit generation of rate-limiting enzyme(HMG-CoA reductase)in the cholesterol synthesis process,this can lead to reduction of cholesterol,so it can promote synthesis of low density lipoprotein receptor,the drug is one of the important drugs for treatment of cardiovascular diseases.But monascus fermentation yield of the drug is low,its purification is also diffcult,how to use modern fermentation technologies to improve lovastatin yield is one of the main research directions.The objective of this study is to screen and mutate good bacterial strains with high lovastatin yield,and to investigate solid fermentation conditions,it can provide basement for large-scale production of lovastatin,the detailed research results are as follows:1.HPLC method was used for detection of lovastatin content,chromatographic conditions were as follows:the column used was Amethyst C18-H(5um,4.6×250mm)column,the inject volume was 10 ?l,the mobile phase was methanol:0.1%phosphoric acid=80:20,the flow rate was 1.0 mL/min.Under these conditions,content of lovastatin can be detected accurately and stably,the method has good linearity,r=0.9999,in precision test,RSD was 0.32%,in repeatability test,RSD was 0.50%,in robustness test,RSD was 1.94%,recovery scope of the method was 98.2%?103.8%,with RSD of 1.86%.2.34 kinds of red kojic rice were collected,monascus Ml strains were separated and purified,they were identified as the Fungi,Eumycota,Ascomycotina,Plectomyhcetes,Eurtoitales,Monascaceae,Monascus Van.tiegh.Solid fermentation yield of lovastatin was 303.3?g/g.3.Ultraviolet light-lithium chloride compound mutation was performed for M1 strains,the mutagenesis condition was:ultraviolet radiation time 80s,LiCl 0.95%,25 strains with obvious variable colonial morphology were obtained,solid fermentation was performed for each strain,lovastatin eontent was detected with HPLC method.Compared with M1 strains,4 strains which with higher lovastatin yield were obtained,stain codes were respectively M1-7?M1-9?M1-16?M1-21,therein,M1-16 had the highest lovastatin yield(1058?g/g),through 5 times'continuous cell culture,its lovastatin yield was stable.4.The optimum fermentation condition of monascus M1-16 strain was determined by single factor experiments and orthogonal experiments,the condition is as follows;the medium contains rice,1%glucose,0.2%monopotassium phosphate;quantity of rice is 100kg(the thickness is about lem),initial water content is 45%,initial PH of the medium is 5.0,inoculum size is 6%,variational fermentation temperature is used(it is cultured for 6d at 30 C,then it is cultured for 10d at 26?),culture humidity is 35%,fermentation time is 16d.under this fermentation condition,yield of lovastatin can reach to 1316?g/g,compared with the original fermentation condition,the yield is increased by 30%.