茶多酚和硫辛酸对谷氨酸发酵的影响

Effects of the supplementation of tea polyphenols and lipoic acid on glutamic acid fermentation

谷氨酸棒杆菌发酵生产谷氨酸的过程中,在生产菌株进入产酸期后,可以通过加大通风量以提高菌体活力,达到提高谷氨酸产酸率的目的。然而,提高供氧量会使菌体氧化代谢加快,虽然产酸量增加,但是菌体老化速度也相应加快,缩短高产酸持续时间。在发酵培养基中添加20 mg/kg的茶多酚和10 mg/kg的硫辛酸,利用茶多酚和硫辛酸的抗氧化特性,清除菌体氧化代谢中积累的过量自由基,减少自由基对菌体的伤害,降低发酵中后期菌体的衰老速度。结果表明:通过添加茶多酚和硫辛酸,谷氨酸质量浓度提高0.9 g/dL,糖酸转化率提高1.1%,谷氨酸发酵的生产效率得到显著提高。

In the process of fermentation to produce glutamic acid by Corynebacterium glutamicum,the oxygen aeration is commonly increased to promote the bacterial viability,and thus to improve the production of glutamic acid after the production strain enters the acid-producing stage.However,with the increase of oxygen supply,the oxidative metabolism of bacteria is accelerated,alongside the high-rate production of glutamic acid.This increases the aging of the C.glutamicum strain,and accordingly,shortens the duration of the high-producing stage.In this study,we investigated the effects of adding tea polyphenols(20 mg/kg) and lipoic acid(10 mg/kg),two well-known antioxidants,on the fermentation of medium.The addition of these two antioxidants was presumably helpful for removing excessive free radicals accumulated by the oxidative metabolism of bacteria,reducing the damage to the bacteria caused by free radicals,and thus reducing the aging of bacteria in the middle and late stages of fermentation.The results indicated that the supplementation of tea polyphenols and lipoic acid indeed increased the titer of glutamic acid by 0.9 g/dL,and the yield by 1.1%.Thus,the addition of tea polyphenols and lipoic acid is a useful strategy to improve the fermentative production of glutamic acid.