The Study On Ion Beam And UV Compound Mutation Of Monascus And Production Of Citrinin

Monascus belongs to the Eusscomyetes,Ascomyca,Euascomydetes,Eurotiales,Monascus,Monascus[1].In ancient times widely used in food coloring,fermented bean curd,wine and Chinese medicine.Japanese scholars first discovered that lovastatin this secondary metabolite can be used as medicine,but the other metabolite citrinin is a mycotoxin,harmful to human body.N⁺ mutation was used to produce mutants of M-14 in my study.The contents of lovastatin in the fermentation products were determined by high performance liquid chromatography?HPLC?,and the high yield lovastatin strain M50-2 was obtained.In order to screen out low citrinin yield strain,as a starting strain,the high-yield lovastatin Monascus strain M50-2 was treated by ultraviolet,which was selected by N⁺ ion beam mutagenesis.The starting strain was irradiated at 30 cm under a 30 W UV lamp,the dose were 30,60,90,120,and 150s.The contents of citrinin and lovastatin in the fermentation products were determined by high performance liquid chromatography?HPLC?with fluorescence detection??ex = 331 nm,?em = 500 nm?and ultraviolet detection?? = 238 nm?after the liquid fermentation of the resulting mutagenized strain.According to the content and growth condition of citrinin,the high-yield lovastatin strain with low production of citrinin was screened out,and the genetic stability analysis was carried out.The fermentation condition was optimized for the mutant strain,and the most suitable fermentation medium and culture conditions were selected.The results are as follows:1.M14 was treated with 78�10¹³ N⁺/cm²,130�10¹³ N⁺/cm²,182�10¹³ N⁺/cm² and 234�10¹³ N⁺/cm².The contents of lovastatin in the fermentation products were determined by high performance liquid chromatography?HPLC?,and the high yield lovastatin strain M50-2 was obtained.2.M50-2 was irradiated with 30,60,90,120 and 150 s at 30 cm under 30 W UV lamp.The optimal mutagenic dose was 120 s based on the positive mutation rate and lethality of mutagenic strains.3.Based on the content of citrinin and growth,the strain M120-1 from the mutant strain was screened out,citrinin content was 2.15 mg/L,with respect to the original strain decreased 96.6%,while the yield was 0.338 lovastatin Mg/ml,which was only 16.5%lower than that of the original strains.The genetic stability test was carried out.The yield of 12 generations of citrinin and lovastatin was stable in subculture.4.The optimal fermentation conditions of low-yield citrinin for M120-1 were Glycerol 5%,corn steep liquor 2%,NaNO3 1%,CH3COONa 1%,methionine 0.5%,KH2PO4 0.2%,MgSO4 � 7H2O 0.2%.PH 4,temperature 32?,rotation speed 160r/min,fermentation time 8 days.