青霉素钠与氯化钠对N-乙酰神经氨酸发酵的影响

重组枯草芽孢杆菌生产N-乙酰神经氨酸的过程中,通过加入表面活性剂和抗生素等方法来改善细胞通透性,以减少产物和副产物所带来的反馈抑制,从而促进细胞生长和产物的合成.对比研究了吐温20、吐温60、吐温80及青霉素钠对重组枯草芽孢杆菌摇瓶和5L发酵罐发酵的影响,确定青霉素钠具有明显增强该菌种发酵产N-乙酰神经氨酸的效果.通过对青霉素钠的添加时间和添加量进行了优化,确定在10h和34h均添加200mg·L-1青霉素钠最优,使N-乙酰神经氨酸的产量达到7.17g·L-1,相比对照提高了38.42%.在利用青霉素钠提高目标产物的基础上,又通过在发酵培养基成分中添加0.75%氯化钠来改变细胞渗透压,从而增强细胞通透性.实验证明,N-乙酰神经氨酸的产量进一步增加,最终达到7.96g·L-1.

Effects of penicillin sodium and sodium chloride on the production of N-Acetylneuraminic Acid

The present study aimed to enhance the production of N-Acetylneuraminic Acid(Neu5 Ac)produced by recombinant Bacillus subtilis.Some methods were studied in the fermentation process,such as adding surfactants and antibiotics,which may allow to weaken the feedback inhibition caused by products and by-products.And the effects of different Tween and penicillin sodium on the fermentation of recombinant Bacillus subtilis in the shake flasks and 5-L fermenter were investigated.As a result,it was confirmed that penicillin sodium could significantly enhance the fermentation yield of N-Acetylneuraminic Acid.Moreover,the optimal time and dosage of penicillin sodium were determined through a series of experimental optimization.The yield of N-Acetylneuraminic Acid reached to 7.17 g·L-1,increased by 38.42% under optimal condition in which 200 mg·L-1 sodium penicillin was added into the medium at 10 hand 34 h,respectively.Based on the action of penicillin sodium,the cell osmotic pressure was adjusted by adding 0.75% sodium chloride into the medium components to enhance cell permeability.The results showed that the production of N-Acetylneuraminic Acid increased further,and eventually the yield of7.96 g·L-1 was achieved.