Studies On Solid-State Fermentation Conditions For Lactase Production And Purification Of Lactas

Lactase (lactase) is called β-D-galactoside galactose hydrolase ((3-D-galactohydrolase), referred to as (3-galactosidase ((3-galactosidase), its widely used in food, medicine, analysis. The Mucor as the starting strain, The subject studied the composition of the solid-state fermentation and fermentation conditions by using solid-state fermentation manner, while establishing a simple method of extractionand purification of lactase and it studied preliminarily in the nature of lactase enzyme.The cost of the high extracellular lactase Lactase is low;the production process can not be easily infected with bacteria;good stability and easy to save, Therefore it has a broad prospect and a good market value.(1) Through a single factor and orthogonal tests defined the main component of the solid-state fermentation medium for the bright strains of Mucor is wheat bran and water, the ratio is1:1.5; plus carbon source lactose0.05g/mL, plus a nitrogen source, peptone0.04g/mL, inoculum10%, adding amount of0.1%potassium dihydrogen phosphate salts. Reuse fermented medium allows lactase production increased45%.It is found that when solid-state fermentation about24h, strains began to produce lactase secretion;the lactase production reached the maximum at72h;optimal incubation temperature is45℃; mixing can make the biggest production of lactase at every24h by Studying a single factor experiment. Finally deciding the enzyme lactase activity is2.45U/g.(2) By the study of different flocculants on the crude enzyme lactase liquid flocculation effect it is determined the inorganic flocculant aluminum sulfate has good flocculation, the optimum adding amount0.002g/mL. At30℃. its flocculation is the best. Under these conditions.the flocculation rate is88.27%.the filtration rate is1.52mL/min. the clarify rate of91.46%, the rate of the enzyme recovery is87.9%.(3) By the classification of sulfuric salting, the purified of SephadexG-100and DEAE-cellulose-52. it is detected to be a single test strip by SDS-PAGE, which get to electrophoretically purity. Its specific activity508.52±0.35U/mg. the yield is42.72%. the purification multiples is38.71.(4) By purifying of the lactase with ONPG as substrate,the enzymatic properties is: the Optimum pH is4.5. When the pH more than6.0, the enzyme activity decreased significantly; its optimal reaction temperature is60℃, the range of temperature is wider.It has higher tolerance at30-60℃, pure enzyme solution has good stability under refrigeration4℃.