Study On Mutation And Breeding Of High Yield Monacolin K Monascus Spp. And Optimization Of Its Solid-state Fermentation Condition

Monacolin K (Lovastatin) is a secondary metabolite of Monascus, which can effectively inhibit cholesterol biosynthesis key enzyme HMG-CoA (3-hydroxy-3-methylglutaryl-coenzyme A reductase) activity, and regulate the body abnormal blood lipid levels. It has many physiological functions such as:lowering blood pressure, protecting the kidney, inhibitioning of cancer et al. Monacolin K in red fermented rice was a kind of natural drugs to inhibit cholesterol synthesis, lipid-lowering drug of choice and the spotlight.The method for Monacolin K determination in red yeast rice fermented by mutated strain was eatablished. The UV-LiCl was used to mutate high-productive Monascus strain, and the solid-state fermentation conditions were optimized.The main research results show as follows:1,Micellar electrokinetic capillary chromatography for Monacolin K determinati-on in red fermented rice was developed. The assay conditions including pH and the concentration of running buffer, the organic additive, the concentration of sodium dodecyl sulfate (SDS),and the separation voltage were optimized. Under the optimized conditions (20 mmol/L borate buffer (pH 10.6, containing 10%(v/v) methanol,40 mmol/L SDS), the Monacolin K can be separated within 23 min, with a linear working range of 5.00-100.00 mg/L (R2=0.9976) and a detection limit (S/N=3) of 0.13 mg/L. The recoveries was varied between 98.5% and 99.5% and the relative standard deviations were lower than 5%.2,Monacolin K in the red rice fermented by 32 Monascus strains were screened and four strains with high yield were choose to muted by UV-LiCl. Finally, a high and stale productive strain M16-4 with the productivity 250.54μg/g.3,Effect of different culture medium on yield of Monacolin K was studied by single factor test and Response surface methodology (RSM) experiments. The results showed that the best culture medium for M16-4 was as follows:glycerol 5%, Corn Steep Liquor 2%, NH4NO3 1%, Sodium Acetate 1%, Methionine 0.5%, KH2PO40.2%, MgSO4 0.2%.Based on these medium and the better cultivating conditions were:50% initial water content of the culture medium, seeding volume 10%, changing culture temperature(30℃for 3 days,26℃for 12 days), fermentation time 15d, initial pH5.5, filled rice amount 25 g/250mL flask. Under conditions, the production of Monacolin K for Monascus M16-4 was improved to 380.4μg/g, and the content of citrinin was 0.28μg/g.