真菌Simplicillium lanosoniveum胞外多糖合成条件的优化及其动力学分析

Optimization and kinetics analyses of exopolysaccharide production by Simplicillium lanosoniveum

Simplicillium lanosoniveum(DT06)是一种能够合成特殊胞外多糖的半知菌类真菌。本文以真菌DT06为研究材料,采用BBD设计原则的响应面法优化其胞外多糖的合成工艺条件,并对其发酵动力学参数进行分析。在单因素实验的基础上,以胞外多糖得率为响应值,确定多糖合成的最优条件:初始p H4.87,葡萄糖40.65 g/L,蛋白胨10.38 g/L,温度30℃,转速140 r/min。优化后真菌DT06胞外多糖得率可达0.139 g/g,比优化前提高了32%。在此优化条件下,对DT06的发酵过程进行动力学分析,结果表明:DT06最大比生长速率μmax=0.156 h-1,其多糖合成与菌体生长部分偶联。与其它产多糖的真菌相比,DT06合成多糖的最大比合成速率较高达到0.066 h-1,但总的多糖得率却较低。碳平衡计算发现DT06还产生一种未知的中性含碳产物,其碳得率为0.129 g/g。上述实验为DT06多糖发酵过程的调控及其胞内代谢网络的优化提供了依据。

The optimum synthesis conditions and fermentation kinetic parameters of Simplicillium lanosoniveum DT06 which was a Deuteromycetes fungus being capable of producing unique exopolysaccharide （EPS）was researched.Based on single factor experiment, the optimum culture conditions for EPS yield coefficient were determined applying Box- Behnken design （BBD）. Under the optimized conditions （40.65 g/L glucose, 10.38 g/L peptone, pH4.87, temperature 30 ℃ and rotation speed 140 r/min） ,the highest EPS yield coefficient 0.139 g/g was obtained, which increased 32% compared with that before optimization. Kinetics analyses indicate that the maximum specific growth rate（μmax）of DT06 was 0.156 h-1, while its EPS synthesis was semi-growth-associated with a maximum specific production rate 0.066 h -1 ,which was relative higher than those of other EPS-producing Fungi. Nevertheless its average EPS yield coefficient was relative low.Carbon-balance analysis revealed that apart from EPS DT06 also produced a unknown products with a carbon yield coefficient of 0.129 g/g. These results provided essential parameters for controlling DT06＇ s fermentation process and improving its metabolic network.