Optimization of High-Density Fermentation Conditions for Thermostable α-L-Rhamnosidase Produced by Recombinant E.Coli
In order to reduce the production of acetic acid and improve the production of thermostable α-L-rhamnosi-dase from recombinant E.coli,the effects of exponential fed-batch,two-stage exponential fed-batch,induction temper-ature and induction pH on acetic acid content and enzyme yield were investigated in the fermentation process of recom-binant E.coli for thermostable α-L-rhamnosidase(TstRhaA).The optimal fermentation process was determined as fol-lows:specific growth rate before induction was 0.2 h-1,specific growth rate after induction was 0.18 h-1,induction tem-perature was 33℃,pH 7.2.Under the optimal fermentation conditions,the concentration of acetic acid was always be-low 0.8 g/L,the maximum DCW was 69.6 g/L,and the highest enzyme activity was 589.0 U/mL,which was 23.4 times of that of shake flask fermentation.The results showed that efficient production of TstRhaA could be achieved by adjust-ing the acetic acid content in an appropriate range during high-density fermentation in E.coli,which had important guiding significance for the high-density expression of other enzymes.
α-L-rhamnosidaseEscherichia coliacetic acidhigh density fermentation
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