Screening Chymosin-micoorganism In Monascus , Identification Of The Living And Optimization Of Solid-state Fermentation Conditions

Cheese, nutritious and delicious, storage and a wide range of long period, is an important part of food in the world, known as "King of dairy products," said. Cheese in the processing, chymosin should arouse sufficient attention. Cheese produced in the world is mainly used chymosin, resulting in an slaughter of more than 5000 million calves a year. It still can not meet the market demand. It is broad development of chymosin.In dissertation, one microorganism, producing chymosin was isolated from monascus. The microorganism in the PDA culture medium show: small white colonies in the initial period, and then the colonies began to old growth, fuzz growing. At the same time, colony color began to change gradually from white to red, purple, dark purple, purplish black. colonies convex, the center subsidence, the main shape of carpet-like colonies, time to nurture colonies appear radial grooves, edges smooth and tidy. Scanning electron microscope found that: cell into the ellipsoid type, surface depression.The experiment found that: the strains, passaged eight times, remained stable. The optimum growth temperature is between 30℃to 35℃. Chymosin is the secondary metabolites of strains. The fermentation process have a smaller decline in pH, and then stabilized at pH6 .5 or so.Meanwhile, the paper also received a conditional strain of the most solid-state fermentation: the best carbon source for the rice, the best nitrogen source for soybean meal, the best fermentation initial pH for 6.5, optimal fermentation temperature for 30℃, optimum fermentation time for 12 days. The best ratio of carbon and nitrogen of 5:2, glucose adding amount of 3.5%, calcium chloride adding amount of 1.5%, dipotassium hydrogen phosphate adding amount of 2.0%, water content of 60%. In the above-mentioned conditions, the crude enzyme liquid-clotting enzyme activity can be achieved 90.56SU/mL.Crude extract, obtained by centrifugation, low temperature concentration, Sephadex G-75 molecular sieve chromatography and cellulose anion-exchange chromatography, has been a high purity chymosin. Among them, Sephadex G-75 molecular sieve chromatography in two peaks of activity after the peak, cellulose gel ion-exchange chromatography in the NaCl concentration of 0.4mol / L peak in the chymosin of live high purity product obtained Electrophoresis pure chymosin will initially be applied to the production of cheese. On the same process conditions, monascus fermentation broth ,as compared , is used to the cheese as a quality of about a difference of 8.4% to calf chymosin.