Abstract: Lactose was used to replace isopropyl β-D-1-thiogalactopyranoside (IPTG) as inducer, the feeding strategy was optimized to improve cell density, induction strategy was studied for improvement of L-glutamate oxidase (LGOX) activity, the whole-cell conversion biocatalyst from high cell density fermentation was used to produce a-ketoglutaric acid (a-KG) from L-glutamic acid. The results showed that LGOX activity was up to 4.78 U/mL from 3.12 U/mL by IPTG induction in the shake flask. In a 5 L fermenter, cell density was increased from 2.49 to 41.6 g/L, and LGOX activity reached 59 U/mL with two-stage feeding strategy combining the exponential feeding with DO-stat feeding strategy. By optimizing the induction strategies, the maximal cell density and LGOX activity reached 48.4 g/L and 156.1 U/mL, improvement of 19.4- and 50-fold before optimization, respectively. a-KG yield was up to 5160 g/L by whole-cell conversion, increased by 48-fold.

Key words: L-glutamate oxidase, a-ketoglutaric acid, fermentation, whole-cell conversion

摘要： 以乳糖代替异丙基硫代半乳糖苷(IPTG)作为诱导剂，优化补料策略提高菌体密度，优化诱导策略提高蛋白表达，以高密度发酵所得L-谷氨酸氧化酶(LGOX)全细胞转化L-谷氨酸生产a-酮戊二酸(a-KG). 结果表明，摇瓶培养条件下LGOX酶活由IPTG诱导的3.12 U/mL提高到4.78 U/mL；通过指数补料与DO-stat补料相结合的两阶段补料策略，5 L发酵罐中细胞浓度由IPTG诱导的2.49 g/L提高到41.6 g/L, LGOX酶活为59 U/mL. 优化诱导策略后细胞浓度为48.4 g/L, LGOX酶活提高到156.1 U/mL，分别是优化前的19.4和50倍，a-KG产量达5160 g/L，提高48倍.

关键词: L-谷氨酸氧化酶, a-酮戊二酸, 发酵, 全细胞转化