SAM产生菌酿酒酵母HYS98发酵动力学及比生长速率控制策略

通过恒化培养对S-腺苷甲硫氨酸(SAM)产生菌酿酒酵母HYS98发酵动力学进行了研究. 结果表明，该菌株的生长与限制性基质蔗糖浓度之间符合Monod关系式，最大比生长速率μmax为0.28 h-1，饱和常数KS为1.27 g/L；当0.005 h-1≤μ≤0.11 h-1，产物生成模型为qSAM=-1.39μ2+0.19μ，底物消耗动力学模型为qS=μ/0.62+0.012. 基于建立的动力学模型，提出了分阶段控制菌体比生长速率的流加培养策略，据此策略在5 L反应器中发酵24 h，SAM浓度达3.56 g/L，而SAM产率达0.15 g/(L·h)，比文献报道的最高水平高67%.

Kinetics and Specific Growth Rate Control Strategy of Saccharomyces cerevisiae HYS98 Fermentation for High Productivity of SAM

The fermentation kinetics of S-adenosyl-L-methionine (SAM) producing Saccharomyces cerevisiae HYS98 was studied through chemostat cultivation. The results showed that the relationship of biomass specific growth rate (μ) and residual sucrose concentration was in accordance with the Monod equation μ=μmaxCS/(KS+CS), where μmax=0.28 h-1, KS=1.27 g/L. The production of SAM followed the mathematical equation qSAM=-1.39μ2+0.19μ, when 0.005 h-1≤μ≤0.11 h-1. The sucrose consumption kinetics followed the equation qS=μ/0.62+0.012. To maximize the SAM productivity, a two-stage process control strategy was proposed based on the kinetic studies. By applying the strategy to the cultivation in a 5 L bioreactor, the accumulation of SAM reached 3.56 g/L and its production rate reached 0.15 g/(L·h) in 24 h, which was 67% increase over the highest level reported so far.