The Characteristics of Cellulase and Amylase fromB.amyloliquefaciens FAJT-8754 and Optimization of Fermentation Conditions

Eight Bacillus strains which produce cellulase and amylase were screened from 140standard Bacillus strains by using starch medium and carboxymethylcellulose sodium(CMC-Na)plate screening method.FJAT-8754had the highest cellulase and amylase producing activities and the biological characterizes(e.g.growth curves,dynamic changes of enzyme activity and enzymatic properties)were tested.Our results suggested that the stationary phase of FJAT-8754was at 28h,the colony count was 4.41×109 cfu·mL-1 at 44hand the activity of cellulase and amylase peaked at 36hsimultaneously.Meanwhile,the optimum reaction conditions for cellulase were at pH5.5,55℃,Vmaxwas 5.14×10-3 mg·mL-1·min-1 and Km was 7.71×10-1 mg·mL-1;the optimal reaction conditions of amylase were at pH 5.5,60℃,Vmaxwas 3.35×10-2 mg·mL-1·min-1 and Km was 6.03×10-3 mg·mL-1.Furthermore,uniform design assays showed that the optimal submerged culture conditions for cellulase and amylase was at pH 6.2,fermentation temperature was at 37.5℃,shaking speed was 180r·min-1,and the activity of cellulase and amylase could reach 202.9,2 392.9U·mL-1,respectively.