Screening and identification of cellulase-producing strain and optimization of the fermentation conditions
To make full use of the resources of waste mulberry branches,which would better use of cellulase in feed additives,a cellulase-producing strain was obtained from the soil of mulberry field,with sodium carboxymethylcellulose(CMC-Na)as the only carbon source.According to its morphology and molecular biology,the strain was identified as Bacillus velezensis and named as Bacillus velezensis XL3.The medium composition and fermentation conditions for this strain to produce cellulase were optimized by the single factor experiment,the main factors which affected cellulase activity were evaluated by Placket-burman design,three significant factors were selected and the optimal area of the response surface methodology was determined by the steepest climbing experimental,the optimal fermentation conditions were obtained by using a three-factor and three-level Box-Behnken experiment.The results showed that temperature,pH and fermentation time were the significant factors for B.velezensis XL3 fermentation and the optimal fermentation conditions for the strain producing cellulase were:the fermentation temperature 34.73℃,initial pH 5.26 and fermentation time 6 days.Under this optimum condition,the cellulase activity reached(233.540±1.74)U/mL,which was about 1.28 times higher than that before optimization.The study provided a theoretical foundation for the utilization of mulberry branch cellulose.
screening and identificationcellulasefermentation parameters optimizationresponse surface
万方数据
维普
