为了寻找高效的产纤维素酶增效蛋白菌株,建立一种筛选方法从土壤中筛选得到一株产纤维素酶增效蛋白的细菌POEP1,其所产增效蛋白对纤维素酶(来源于黑曲霉Aspergillus niger)的滤纸酶活有明显的增效作用,通过对其进行16SrDNA分类鉴定,确定该菌株为栖稻假单胞菌(Pseudomonas oryzihabitans)。为进一步提高POEP1产纤维素酶增效蛋白的水平,对其培养条件进行优化。采用单因子试验筛选出最佳碳源为麦麸,最佳氮源为黄豆粉。再通过Plackett-Burman设计对与发酵相关的11个因子进行试验,筛选出麦麸、黄豆粉和KH2PO4为3个主要显著因子;由Box-Behnken实验结合响应面分析确定主要因子的最优水平为:麦麸质量浓度32.3 g L 1,黄豆粉质量浓度24.7 g L 1,KH2PO4质量浓度4.36 g L 1。优化后纤维素酶增效蛋白的产量提高1.7倍,增效活力由15.79 U mL 1增至43.31 U mL 1。
A self-designed screening model was built for the screening of the high-efficient cellulaseenhancing-protein producing strains.A strain(named POEP1),having the ability of producing cellulase-activity-enhancing-protein,was isolated from the soil,and then according to the 16S rDNA gene sequencing analysis,the strain was identified to be Pseudomonas oryzihabitans.Some fermentation conditions were optimized to increase the protein productivity.The most suitable carbon and nitrogen sources were determined to be wheat bran and soybeans meal in the single-factor experiments,respectively.Three key factors such as mass concentrations of wheat bran,soybeans meal and KH2PO4 were selected from eleven factors affecting the protein productivity by Plaekett-Burman design and were further optimized by Box-Behnken design and response surface methodology.The optimal concentrations of these three important factors were obtained as follows 32.3 g.L.1 of wheat bran,24.7 g.L.1 of soybeans meal and 4.36 g.L.1of KH2PO4.Under the optimal conditions,the cellulase-enhancing activity of 43.31 U.mL.1 was obtained,which is 1.7 times higher than that before optimization(15.79 U.mL.1).