Screening And Characteristics Of Cellulase And Amylase Producing Bacillus Strain

Cellulase and amylase are the important component of feed compound enzyme preparation, and screening with a strain of high-yield composite enzyme has great significance.In this study, Bacillus amyloliquefaciens FJAT-8754, screened from Agricultural Bioresource Research Institute, Fujian Academy of Agricultural Sciences, has a higher compound enzyme activity.The growth characteristics of B. amyloliquefaciens FJAT-8754 has been preliminary studied. The results show that corn starch is the carbon source, soybean meal is preferably nitrogen, carbon-nitrogen ratio is 1:1, initial pH value of culture medium is 6.0, the culture temperature is 35 ℃, and shaking speed is 170 r/min. In this condition culture for 36 h, in the fermentation the cell concentration, cellulase activity and amylase activity of Bacillus amyloliquefaciens FJAT-8754 are 4.1×109 cfu/mL,135.7 U/mL and 1543.3 U/mL.A preliminary study on the properties of cellulase and amylase of B. amyloliquefaciens FJAT-8754 show that the optimum reaction pH value of cellulose is 5.5, optimum reaction temperature is 50 ℃, the activity of cellulase promoted by Ca2+, Zn2+ and low concentration of Mg2+, and inhibited by Al3+, Cu2+ and Mn2+, and Vmax is 5.14×10-3 mg/(mL·min), and michaelis constant Km is 7.71 ×10-1 mg/mL; The optimum reaction pH value of amylase is 5.5, optimum reaction temperature is 55 ℃, low concentration of Mg2+, Al3+, Zn2+ are the promoter of amylase, and Ca2+, Cu2+, Mn2+ as inhibitors, Vmax is 3.35×10-2 mg/(mL·min), Michaelis constant Km is 6.03×10-J mg/mL. And the cellulose and amylase was highly active in the alkaline range of pH (3.5～7.5), but the thermal stability of composite enzyme is poor.Through uniform design, the optimal submerged culture conditions for cellulase and amylase was at pH 6.2, fermentation temperature 37.5 ℃, shaking speed 180 r/min and the activity of cellulose and amylase reached up to 202.9、2392.9 U·mL-1. Test measured values were lower than the theoretical value of 13.58%,7.76%, but were increased by 49.5%,55.1%.Through the preliminary experiments in 50L fermentor, established the growth kinetics, product synthesis kinetics and substrate consumption dynamics model of B. amyloliquefaciens FJAT-8754 in this condition.And determine that the aynthesis of cellulase and amylase both are growing part of the relevant type.