生物基1,3-丙二醇连续发酵过程的稳态分析与反馈控制

Steady-state analysis and feedback control of continuous fermentation for bio-based 1,3-propanediol

生物发酵甘油生产1,3-丙二醇的自动化控制是其工业化应用亟待解决的关键问题。首先,采用数学函数连续性分析深入研究了克雷伯氏杆菌连续发酵甘油生产1,3-丙二醇过程的多稳态特性。在不同的初始甘油浓度或稀释速率下,系统均会出现多稳态现象,通过双因素分析确定了多稳态出现的临界区域,该区域内部的稳态是不稳定的。之后,基于反馈控制理论和多稳态分析结果,设计优化了受残余甘油和产物浓度影响的稀释速率控制策略。在连续发酵过程中,调整时间从81.27 h缩短到34.11 h,显著提高了发酵初期阶段甘油的利用率;同时甘油转化率由0.478 mmol·mmol^(-1)提高至0.563 mmol·mmol^(-1),生产强度由85.70 mmol·L^(-1)·h^(-1)提高到101.10 mmol·L^(-1)·h^(-1),显著提高了生产性能。

The automatic control of biologically fermented glycerol to produce 1,3-propanediol is the key problem to be solved in its industrial application.First,according to the mathematical model of the fermentation for Klebsiella pneumoniae to produce 1,3-propanediol,the multi-steady characteristics of continuous process were studied through the numerical continuation analysis for mathematical functions.Thereby,it was found that under different initial glycerol concentration or dilution rate,the system exhibited multi-steady state phenomenon.Through two-factor analysis,the critical region where multi-steady state occurs was determined,and the steady state in this region was unstable.After that,based on the feedback control theory and the results of multi-stability,the dilution rate control strategy affected by the concentration of residual glycerol and product 1,3-propanediol was designed.In the continuous fermentation,the settling time was shortened from 81.27 h to 34.11 h,which could significantly reduce the loss of glycerol in the early stage of fermentation.Meanwhile,the yield of 1,3-propanediol was increased from 0.478 mmol·mmol^(-1) to 0.563 mmol·mmol^(-1) and the production productivity was increased from 85.70 mmol·L^(-1)·h^(-1) to 101.10 mmol·L^(-1)·h^(-1).The results showed that the feedback control of the dilution rate significantly improved production performance,which can be adopted as a feeding guide for continuous culture in practice.