黑曲霉菌丝体活力对α-L-鼠李糖苷酶发酵的影响

Effects of the mycelium viability on α-L-rhamnosidase production by Aspergillus niger fermentation

α-L-鼠李糖苷酶是工业上一种重要的水解酶。为了方便地优化和监控α-L-鼠李糖苷酶的发酵生产过程,在5 L发酵罐水平研究黑曲霉菌丝体活力与α-L-鼠李糖苷酶产量之间的关系,菌丝体活力采用TTC-脱氢酶法进行测定。实验结果表明,在发酵过程中维持适宜的菌丝体活力对α-L-鼠李糖苷酶的产量非常重要:当摇瓶种子菌丝体活力达到最大值0.388 U/mL时,对应的5 L发酵罐中α-L-鼠李糖苷酶的产量最大;控制发酵过程的pH恒定于5.5,可以有效延缓菌丝体活力下降速度,使α-L-鼠李糖苷酶的产量提高28.7%;当搅拌转速低于400r/min或通气量低于0.3 vvm时,发酵24～36 h的菌丝体活力大幅下降,α-L-鼠李糖苷酶的产量显著降低。因此,可以将菌丝体活力作为α-L-鼠李糖苷酶发酵工艺优化和生产过程控制中一项重要的监控参数。

α-L-Rhamnosidase was an important hydrolytic enzyme in industry. We had investigated the relation between the mycelium viability and the yield of α-L-rhamnosidase to optimize and monitor the enzyme production in 5 L fermentation tank. The mycelium viability was measured by the triphenyltetrazolium chloride （TTC） method. The results showed that maintaining appropriate mycelium viability in fermentation was significant for α-L-rhamnosidase production. When the mycelium viability of inoculum in shake flask reached to the maximum 0. 388 U/mL, the yield of α-L-rhamnosidase in 5 L fermentation tank was the highest. Controlling the pH at 5.5 during fermentation could ef- fectively slow down the decline speed of mycelium viability in fermentation end, and correspondingly increase 28.7% of the α-L-rhamnosidase yield. When the agitation speed was below 400 rpm/min or the air flow was less than 0.3 vvm, the maximum mycelium viability and α-L-rhamnosidase yield was remarkably low. Therefore, the mycelium via- bility could be used as an important parameter in fermentation optimization and process control of α-L-rhamnosidase production.