促溶剂对雷斯青霉发酵液流变特性的影响

目的:促溶剂通常用于甾体生物催化过程以提高底物溶解度,但在发酵液中添加促溶剂对菌体形态及发酵液特性的影响还少有报道。方法:利用旋转流变仪和顺磁分析仪分别对发酵液的流变特性及体积氧传递系数KLa进行监测。结果:无论是否添加促溶剂,发酵液都表现出非牛顿流体力学特性,但添加3%1,2丙二醇后同一时期发酵液稠度系数减小大约17%,而流动指数平均增加8%。结论:添加促溶剂使得发酵液表观黏度减小,体积氧传递系数增大,从而有利于甾体化合物的生物转化。

Effect of Cosolvents on Rheological Properties of Penicillium raistrickii Fermentation Broth

Objective:Improved efficiency of steroid microbial transformation by co-solvents is generally attributed to their positive effects on the solubility of substrate in aqueous media,but their impact on microbial morphology and rheological property of fermentation remains unknown.Method:The rheological properties of fermentation broth and volumetric oxygen transfer coefficient KLa were measured by coaxial cylinder viscometer and.paramagnetic oxygen analzer,respectively.Result:Addition of cosolvent in the fermention medium led to different rheological parameters in the fermentation broth although both culture media displayed the non-Newtonian pseudoplastic fluid,compared with the control,17% smaller consistent index(K) and 8% larger flow behavior index(n) were obtained for the 1,2-propanediol-added fermentation broth;At the same time,the correlation analysis on the volume of oxygen transfer coefficient KLa and the flow index n,was carried out.Conclusion:Addition of solvent decreased the fermentation apparent viscosity,increased oxygen transfer coefficient(KLa),which would be also benifit to steroids bioconversion.