基于α-酮戊二酸发酵从7L发酵罐放大到5 m3发酵罐时发现:发酵周期大幅缩短,细胞生长速度加快,丙酮酸大量积累,而α-酮戊二酸的产量降低.为此,考察了不同规模反应器上溶氧控制对细胞生长和产物代谢的影响,发现较高的溶氧水平有利于细胞生长和丙酮酸积累,但细胞容易衰老,影响最终发酵产量；降低溶氧有利于保持细胞活力,有利于丙酮酸进入三羧酸循环转化为α-酮戊二酸的积累.根据这一结果,采用两阶段溶氧控制,同时强化丙酮酸进入三羧酸循环的丙酮酸羧化途径,α-酮戊二酸的产量达到44.1 g/L.为了充分发挥解脂亚洛酵母优越的发酵性能,采用恒速流加甘油策略,α-酮戊二酸产量达到64.2g/L.与7L发酵罐上的相比,周期缩短了24h,生产强度提高了38％.%Abstract When α-ketoglutaric acid(α-KG) production by Yarrowia lipolytica was scaled-up in 5 m3 fermentor from 7 L fermentor,it was found that cell growth rate in 5 m3 fermentor was higher than that of in 7 L fermentor and higher amount of pyruvate was accumulated in the broth.However,α-ketoglutaric acid production decreased.In order to solve this problem,the effect of dissolved oxygen level on α-KG production was investigated.The results showed that the higher dissolved oxygen level could facilitate cell growth and pyruvate accumulation,but was harmful to maintaining cell vitality.Conversely,lower dissolved oxygen level could facilitate the channeling of pyruvate into citric acid cycle to product α-ketoglutaric acid.Therefore,a two-stage control strategy was employed,pyruvate carboxylase activity was improved by feeding CaCO3 from 48 h,α-ketoglutaric acid production reached 44.1 g/L.In order to bring the yeast' s intense secretory ability into full play,constant feeding approach was applied in fed-batch culture.Consequently,the culture time was shortened by 24 h,α-ketoglutaric acid production reached 64.2 g/L with its productivity enhanced by 38％ as compared with that in 7 L fermentor.
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