Department of Biological Engineering, Shanghai Institute of Technology, Shanghai 201418, P.R. China.
Department of Biological Engineering, East China University of Science and Technology, Shanghai 200237, P.R. China.
J Microbiol Biotechnol. 2021 Jun 28;31(6):890-901. doi: 10.4014/jmb.2104.04002.
The 11α-hydroxylation of canrenone can be catalyzed by in bioreactors, where the geometry of the impeller greatly influences the biotransformation. In this study, the effects of the blade number and impeller diameter of a Rushton turbine on the 11α-hydroxylation of canrenone were considered. The results of fermentation experiments using a 50 mm four-blade impeller showed that 3.40% and 11.43% increases in the conversion ratio were achieved by increasing the blade number and impeller diameter, respectively. However, with an impeller diameter of 60 mm, the conversion ratio with a six-blade impeller was 14.42% lower than that with a four-blade impeller. Data from cold model experiments with a large-diameter six-blade impeller indicated that the serious leakage of inclusions and a 22.08% enzyme activity retention led to a low conversion ratio. Numerical simulations suggested that there was good gas distribution and high fluid flow velocity when the fluid was stirred by large-diameter impellers, resulting in a high dissolved oxygen content and good bulk circulation, which positively affected hyphal growth and metabolism. However, a large-diameter six-blade impeller created overly high shear compared to a large-diameter four-blade impeller, thereby decreasing the conversion ratio. The average shear rates of the former and latter cases were 43.25 s and 35.31 s, respectively. We therefore concluded that appropriate shear should be applied in the 11α-hydroxylation of canrenone. Overall, this study provides basic data for the scaled-up production of 11α-hydroxycanrenone.
坎利酮的 11α-羟化可以在生物反应器中被催化，其中搅拌器的几何形状极大地影响了生物转化。在这项研究中，我们考虑了拉森涡轮的叶片数量和叶轮直径对坎利酮 11α-羟化的影响。使用 50mm 四叶片叶轮进行发酵实验的结果表明，分别通过增加叶片数量和叶轮直径，转化率提高了 3.40%和 11.43%。然而，当叶轮直径为 60mm 时，六叶片叶轮的转化率比四叶片叶轮低 14.42%。使用大直径六叶片叶轮进行冷模实验的数据表明，严重的夹带泄漏和 22.08%的酶活性保留导致转化率低。数值模拟表明，当使用大直径叶轮搅拌液体时，气体分布良好，流体流速高，导致溶解氧含量高，整体循环良好，这对菌丝生长和代谢有积极影响。然而，与大直径四叶片叶轮相比，大直径六叶片叶轮产生的剪切过高，从而降低了转化率。前者和后者的平均剪切速率分别为 43.25s 和 35.31s。因此，我们得出结论，在坎利酮的 11α-羟化中应该施加适当的剪切。总的来说，这项研究为 11α-羟基坎利酮的放大生产提供了基础数据。
