Abstract

This study presents the kinetics of production of a glycolipopeptide biosurfactant in a medium previously co-optimized by response surface and neural network methods to gain some insight into its volumetric and specific productivities for possible scale-up towards industrial production. Significant kinetic parameters including maximum specific growth rate, µmax, specific substrate consumption rate, qs and specific biosurfactant yield, Yp/x were determined from logistic model parameters after comparison with other kinetic models. Results showed that bio-catalytic rates of lipase and urease reached exponential values within the first 12 h of fermentation leading to high specific rates of substrate consumption and bacterial growth. Volumetric biosurfactant production reached significantly high levels during prolonged stationary growth and specific urease activity. This suggests that glycolipopeptide biosynthesis may proceed through stationary phase transpeptidation of the glycolipid base. A high cross-correlation coefficient of 0.950 confirmed that substrate consumption and glycolipopeptide production occurred contemporaneously during the 66-h fermentation. The maximum biosurfactant concentration of 132.52 g/L, µmax of 0.292 h^-1, qp of 1.674 g/gDCW/h, rp of 2.008 g/(Lh) and Yp/x of 4.413 g/g predicted by the selected logistic model and a unit cost of €0.57/g glycolipopeptide in the optimized medium may lead to technical and economic benefits.

摘要

这项研究提出了糖脂多肽生物表面活性剂在以前通过响应面和神经网络方法共同优化的培养基中生产的动力学，从而获得了其体积和特定生产率的一些见识，从而有可能扩大到工业生产。在与其他动力学模型进行比较之后，根据逻辑模型参数确定了重要的动力学参数，包括最大比生长速率，µmax，比底物消耗速率，qs和比生物表面活性剂产量Yp / x。结果表明，在发酵的前12小时内，脂肪酶和脲酶的生物催化速率达到指数值，从而导致底物消耗和细菌生长的高比速率。在长时间的固定生长和特定的脲酶活性期间，生物表面活性剂的生产量达到了很高的水平。这表明糖脂肽的生物合成可以通过糖脂碱基的固定相转肽进行。0.950的高互相关系数确认在66小时的发酵过程中同时发生了底物消耗和糖脂肽的产生。最大生物表面活性剂浓度为132.52 g / L，μmax为0.292 h^-1，根据所选逻辑模型预测的qp为1.674 g / gDCW / h，rp为2.008 g /（Lh），Yp / x为4.413 g / g，在优化的培养基中单位糖成本为€0.57 / g糖脂肽带来技术和经济效益。