不同培养方式下dCO_2对黑曲霉发酵产糖化酶的影响

Dissolved Carbon Dioxide Effects on Glucoamylase Synthesis of Aspergillus niger in Batch and Chemostat Cultures

通过在进气中混入部分CO_2气体,在分批培养和恒化培养两种培养方式下研究了不同dCO_2水平对黑曲霉产糖化酶的影响。在分批培养方式下,较高的dCO_2对细胞的生长具有抑制作用,并且随着dCO_2水平的增加,抑制程度加强,但是较高浓度的dCO_2对糖化酶的合成有利。而恒化培养时,低稀释率D_1=0.05/h下,较高的dCO_2对细胞的生长并没有明显的抑制作用,但有利于糖化酶合成。高稀释率D_2=0.08/h下,较高的dCO_2对细胞的生长有明显的抑制作用,并且抑制程度随着dCO_2水平的增加而加大。以上实验结果表明,dCO_2对细胞生长和糖化酶合成的影响不仅和dCO_2水平有关,也和培养方式及细胞所处的特定代谢状态有关。这对于黑曲霉产糖化酶工业放大过程中补料分批发酵中比生长速率的设计具有很好的指导作用。

The effect of different levels of elevated dissolved CO2 availability（ CO2 stress） was investigated in batch and chemostat cultures of Aspergillus niger by gassing with CO2-enriched air. Under batch cultures,higher elevated dissolved CO2 availability in culture medium resulted in a more significant decrease in specific growth rate,whereas it appeared to have a positive effect on glucoamylase synthesis. Under chemostat cultures with low dilution rate（ D1= 0. 05 / h）,high levels of dissolved CO2 led to no reduction of specific growth rate,but an increase of glucoamylase production. Whereas at high dilution rate（ D2= 0. 08 / h）,both substrate uptake and cell grow were more severely inhibited by more elevated dissolved CO2. The effect of elevated dissolved CO2 availability on the fermentation process depends on CO2 levels as well as dilution rate. Therefore,the influence of carbon dioxide on cell growth and glucoamylase production dependent on CO2 levels,cultivation mode and specific metabolic activity, which would be helpful for the design of specific growth rate in scale-up of glucoamylase fermentation by Aspergillus niger.