【摘要】 为优化发酵工艺,通过单罐恒化培养对组成型毕赤酵母X-33产木聚糖酶XYL1的动力学进行了研究,并探讨了比生长速率与菌体生产率和产物生产率的关系.基于动力学研究,在50L发酵罐中采用分段控制工艺表达XYL1.结果表明:比生长速率与葡萄糖浓度的关系基本符合Monod方程,最大比生长速率为0.35 h-1,饱和常数为0.38 g/L;当比生长速率介于0.024~0.212之间时,XYL1生成动力学模型可用一元二次方程描述;比底物消耗速率与比生长速率呈线性关系;最佳稀释速率为0.316 h-1,实验预测的最大菌体生产率为7.509g/(L·h);当产物生产率最大时,比生长速率达0.156h-1;最终发酵菌湿重达(415±12)g/L,酶活达(2788±85)IU/mL,实现了XYL1的高效表达.更多还原

【Abstract】 In order to optimize the fermentation process of constitutive Pichia pastoris X-33 for producing xylanase 1( XYL1),the fermentation kinetics during the single-tank chemostat cultivation was investigated,and the relationship between the specific cell growth rate and the cell productivity as well as the product yield was discussed. Then,based on the fermentation kinetics,batch control scheme was adopted to express XYL1 in a 50-L fermentation tank. The results indicate that( 1) the relationship between the specific cell growth rate and the glucose concentration basically accords with the Monod equation,with a maximum specific growth rate value of 0. 35 h- 1and a saturation coefficient value of 0. 38 g / L;( 2) when the specific cell growth rate ranges from 0. 024 to 0. 212,the kinetic model of XYL1 formation can be described using a quadratic equation with one unknown;( 3) the specific substrate consumption rate is linear to the specific cell growth rate;( 4) the optimal dilution rate is 0. 316 h- 1and the maximum volumetric cell productivity is 7. 509 g /( L·h);( 5) the specific cell growth rate achieves 0. 156 h- 1 when the product yield reaches its maximum; and( 6) after fermentation,the wet weight of cells and the xylanase activity achieve( 415 ± 12) g / L and( 2788 ± 85) IU / mL,respectively,which means that XYL1 is successfully expressed with high efficiency.更多还原