甘油连续生物歧化过程的过渡行为及其数学模拟

用肺炎杆菌将甘油转化为１,３－丙二醇过程对稀释速率和底物进料浓度变化的过渡行为反映了细胞生长和胞内物质代谢在不同条件下存在着显著的差异。体系的过渡响应取决于操作条件变化前后系统所处的状态,当底物浓度由限制状态向剩余状态过渡时,甘油的残余浓度不断上升,而乙醇的浓度则逐渐下降,同时生物量、１,３－丙二醇和乙酸的浓度呈现先增后降的趋势。本文用“甘油浓度变化速率”的概念修正了菌体生长模型,并对甘油歧化过程

Transient Responses and Mathematical Modeling of Klebsiella pneumoniae to Dilution Rate and Glycerol Concentration Step Changes in Continuous Cultures

A quantitative knowledge of dynamic behavior is necessary to understand, optimize and control a bioprocess, particularly in a continuous culture. The study of dynamics in glycerol fermentation by Klebsiella pneumoniae plays an important role because the bioconversion process possesses multiplicity and oscillation under certain conditions. The transient responses of Klebsiella pneumoniae to dilution rate and glycerol concentration step changes in continuous bioconversion of glycerol to 1,3-propanediol was studied in this paper. The experimental results showed that there are distinguished differences between cell growth and intracellular metabolism under different conditions. The transient behavior depended on the both states before and after a step change of operation conditions. When substrate concentration transfered from a limiting condition to a excessive condition, the residual concentration of glycerol in reactor constantly increased, but ethanol concentration decreased gradually as fermentation time. Simultaneously biomass, 1,3 propanediol and acetate concentration increased firstly and then decreased. A novel concept of "glycerol concentration change rate" was used to modify the growth model under steady-state in this paper. The modified model simulated the transient behavior of glycerol bioconversion in good agreement with experimental results.