Wei Gong-Yuan, Li Yin, Du Guo-Cheng, Chen Jian
Key Laboratory of Industrial Biotechnology, Ministry of Education, Southern Yangtze University, Wuxi 214036, China.
Sheng Wu Gong Cheng Xue Bao. 2003 May;19(3):358-63.
Glutathione (L-gamma-glutamyl-L-cysteinylglycine), one of the major non-protein thiol compounds, is widely distributed in living cells and plays an important role in maintaining the normal redox environment of cells as an antioxidant. In the production of glutathione by fermentation, temperature is one of the most important environmental factors that affect the yield and the productivity of glutathione. Here the effect of temperature, varied from 24 degrees C to 32 degrees C, on the batch fermentation of glutathione in a 7 L stirred fermenter by Candida utilis WSH 02-08 was investigated. It was found that cell growth was hastened along with the increase of temperature. The maximum dry cell weight was achieved approximately 16 g/L under various temperatures, as soon as the glucose was exhausted. The effect of temperature on glutathione production was different from that on cell growth: the lower the temperature, the higher the glutathione production, i.e. the maximum glutathione concentration at 32 degrees C (235 mg/L) was only 75% and 64% of that at 30 degrees C and 26 degrees C, respectively. The maximum average specific growth rate (0.13 h(-1)) was achieved at 30 degrees C while the maximum glutathione concentration (366 mg x L(-1)) and the maximum intracellular glutathione content (2.3%) were obtained at 26 degrees C. Therefore, the optimum temperatures for cell growth and glutathione production are quite different in the batch fermentation. A modified Logistic equation was successfully applied to estimate the kinetics of cell growth. The maximum specific growth rate and the substrate inhibition constant, calculated from this equation, were both increased along with the temperature. In addition, the glutathione fermentation by C. utilis WSH 02-08 under various temperatures was proven to be a partial growth-associated process by estimating the process with the Luedeking-Piret equation. Based on the estimated parameon the estimated parameters, the effect of temperature on the kinetics of cell growth was further studied. An equation, dX / dt = [0.0224(T + 1.7)]2 X(1-X/Xmax) / 1 + S/ {8.26 x 10(6) x exp [-31477/R/(T+273)]}, was developed and applied to interlink the relationship between biomass concentration and temperature as well as substrate concentration in the batch glutathione fermentation. The experiment results showed that this model could predict the growth pattern very well.
谷胱甘肽（L-γ-谷氨酰-L-半胱氨酰甘氨酸）是主要的非蛋白质硫醇化合物之一，广泛分布于活细胞中，作为一种抗氧化剂在维持细胞正常的氧化还原环境中发挥着重要作用。在通过发酵生产谷胱甘肽的过程中，温度是影响谷胱甘肽产量和生产效率的最重要环境因素之一。在此，研究了温度在24℃至32℃范围内变化时，产朊假丝酵母WSH 02-08在7L搅拌式发酵罐中分批发酵生产谷胱甘肽的情况。结果发现，随着温度升高，细胞生长加快。在各种温度下，一旦葡萄糖耗尽，最大干细胞重量约为16g/L。温度对谷胱甘肽生产的影响与对细胞生长的影响不同：温度越低，谷胱甘肽产量越高，即32℃时的最大谷胱甘肽浓度（235mg/L）分别仅为30℃和26℃时的75%和64%。30℃时达到最大平均比生长速率（0.13h⁻¹），而26℃时获得最大谷胱甘肽浓度（366mg·L⁻¹）和最大细胞内谷胱甘肽含量（2.3%）。因此，在分批发酵中，细胞生长和谷胱甘肽生产的最适温度有很大差异。一个修正的逻辑方程成功地用于估算细胞生长动力学。根据该方程计算得到的最大比生长速率和底物抑制常数均随温度升高而增加。此外，通过用Luedeking-Piret方程估算该过程，证明产朊假丝酵母WSH 02-08在不同温度下的谷胱甘肽发酵是一个部分与生长相关的过程。基于估算参数，进一步研究了温度对细胞生长动力学的影响。建立了一个方程dX/dt = [0.0224(T + 1.7)]²X(1 - X/Xmax) / 1 + S / {8.26×10⁶×exp[-31477/R/(T + 273)]}，并应用于关联分批谷胱甘肽发酵中生物量浓度与温度以及底物浓度之间的关系。实验结果表明，该模型能够很好地预测生长模式。
