代谢副产物乙酸对L-色氨酸发酵的影响

分析了重组大肠杆菌(E.coli TRTH/pSV-709)发酵生产L-色氨酸的发酵过程,检测结果表明发酵液中有大量代谢副产物乙酸的积累。利用外源添加试验研究了乙酸对L-色氨酸发酵的影响,结果表明乙酸浓度高于2g/L时对L-色氨酸生产菌的生长和产酸均有抑制作用。分析了乙酸的产生机制,并采取了调节溶氧水平、确定合适初始葡萄糖浓度、限制葡萄糖流加及控制菌体比生长速率等措施来减少乙酸的生成。在优化条件下,乙酸含量与原工艺相比降低了51.35%,菌体生物量和L-色氨酸产量分别提高了51.07%和46.54%,实现了高密度发酵培养的目的。

Effect of the Byproduct-Acetic Acid on L-Tryptophan Fermentation

The process of L-Tryptophan fermentation by E. coli TRTH/pSV-709 was investigated, and the result showed that there was a large number of byproduct (acetic acid) in the broth. The effect of acetic acid on L-Tryptophan fermentation was studied by experiments with addition of acetic acid. The results showed that 2 g/L acetic acid could inhibit the growth of L-Tryptophan-producing bacteria and L-Tryptophan production. The mechanism of production of acetic acid was studied. Several strategies including dissolved oxygen regulation, suitable concentration of initial glucose determination, glucose-limited pulse fed-batch and the specific growth rate regulation were applied to reduce the generation of acetic acid. Under the optimal condition, the concentration of acetic acid was decreased by 51.35% compared with that under original condition. Biomass and yield of L-Tryptophan were increased by 51.07% and 46.54% respectively, which accessed high cell density cultivation.