Screening Of Phytase Producer And Study On Phytase Production On Solid-State Fermentation And Enzymological Characteristics

Over 521 strains were screened for phytase production from 30 kinds of soil samples. Out of them, four strains were obtained by the primary screening, then, one strain (LW03), which has higher levels phytase production, was screened by enzyme yielding tests. LW03 strain was primarily identified to be Rhizopus.A high phytase producing Rhizopus N013 strain was obtained from LW03 by mutagenetic treatments, including UV-ray, DES, Co60 Y -ray and NTG.The optimum conditions in wheat bran and rice bran on solid state fermentation were 3% corn starch as additional carbon sources, 4%(NH4)2 SO4 as additional nitrogen sources, 60% moisture content of the medium, 25 . The best levels of phytase production, 92U/g.ssc, appears on the fourth day.Enzymatic properties of the crude phytase were investigated. The optimal temperature for the enzyme reaction was 48 and about 77.4% of its original activity remained after incubation at 72 for 10 minutes. There are two optimal pH, which were 2.4 and 5.6, respectively. The enzyme activity was fairly stable from pH 4.0 ~ 5.5.A non-purified preparation of extracelluar phytase, koji of Rhizopus N013 ,was utilized for predicting inorganic P release from rice bran and rapeseed. Adding 300U/kg phytase in rice bran and rapeseed and hydrolysising 4h,the ratio of dephosphorylation of them was 10% -20% and 50%, respectively, after 16h, were 50% and 99%, respectively.