Isolation And Fermentation Optimization Of Thermal-stable Catalase Producing Strain And Enzymic Characteration Of The Catalase

To obtain catalase that more suitable for industrial application,strains with high catalase activity were isolated from the environment of high temperature.The production conditions of catalase from strain FZSF03 were optimized and catalase in the broth was purified for enzymatic properties study.The main results are as follows:1.The screening and identification of catalase-producing strains with thermal stability.A strain named FZSF03 with high catalase activity had been screened out from the compost and it's original activity was 1321U/mL.The strain was identified according to its morphological characteristics and 16S rRNA gene sequence.The result showed that the homology between strain FZSF03 and Ureibacillus thermosphaericus DSM10633 was 99.37%.So this strain was identified as Ureibacillus thermosphaericus and was named Ureibacillus thermosphaericus FZSF03.2.Fermentation optimization of strains FZSF03.Selecting the optimum carbon and nitrogen sources and inorganic salt to determine optimum liquid medium recipe by the orthogonal test.The optimized fermentation medium contained(g/L):yeast powder 25,maltodextrin 30 and CaCl2 1.The optimized fermentation condition was:pH 7.0,55 ? of the fermentation temperature,60 mL of the suitable medium volume size in 250 mL flasks,6%of the inoculum size and 32 h of the cultivation time.With the optimum conditions,the catalase activities achieved at 41761 U/mL,which was 31.6-fold greater than that of the control.3.Purification of catalase.The catalase of Ureibacillus thermosphaericus FZSF03 was purified to homogeneity by DEAE-SepharoseTM Fast Flow column chromatography,Sephadex G-150 column chromatography and Hydrophobic Interaction Chromatography.The specific activity of the catalase was raised approximately 5.06 fold,from 43360 U/mg proteins to 219360 U/mg proteins,with a recovery of 14.49%.4.Studies on enzymatic properties of catalase.The basic enzymatic properties were investigated using the purified catalase.The results showed that the optimum temperature of catalase was 60 ?,with relative activities retained more than 80%after incubation for 60 min at 60 ?.The catalase was proved to have a good temperature stability.The optimum pH of catalase was 7.0 and have a good pH stabilityat the rang of pH5 to pH 10.The relative activities were all above 80%after dispose for 60 min in this range.The apparent K.and Vma.value of catalase was 100 mmol/L and 3571 ?mol/min respectively,when H2O2 was utilized as substrate.