L-酪氨酸清液发酵工艺研究

Study on Fermentation Process of L-Tyrosine Clear Liquid

传统发酵法生产L-酪氨酸的过程中,培养基中的玉米浆、豆粕水解液和蛋白胨物质容易造成发酵液黏稠浑浊、泡沫多,导致产酸能力下降,杂质和色素对产物的分离提取造成一定的影响。该研究采用等效替代的方法,将培养基中主要氮源玉米浆、豆粕水解液和蛋白胨利用小分子的氨基酸、核苷和生物素近似替代,利用正交实验和单因素实验的方法优化培养基配比。得到L-酪氨酸清液培养基中天冬氨酸、谷氨酸、苯丙氨酸、色氨酸、琥珀酸、生物素、鸟苷、腺苷、肌苷的最佳添加量分别为2.2 g/L、2.4 g/L、1.5 g/L、1.5 g/L、1.5 g/L、1.0 mg/L、0.3 g/L、0.3 g/L、0.4 g/L。研究表明,当利用L-酪氨酸生产菌E.coli TR035 L发酵罐清液发酵35 h时,清液发酵的OD_(600 nm)为98,比对照组的OD_(600 nm)提高18.1%;L-酪氨酸产量为55.2 g/L,比对照组提高22.7%;清液发酵上清液透光率为47.8%,比对照组提高20.9%;清液发酵分离提取率为92.6%,比对照组提高11.7%。表明该清液发酵能很好地提升菌株发酵生产L-酪氨酸的能力及分离提取率。

In the production process of L-tyrosine by traditional fermentation method,corn steep liquor,soybean meal hydrolysate and peptone in the culture medium are easy to cause the fermentation liquid to be thick and turbid,with more foam,leading to the decline of acid production capacity,and impurities and pigments have a certain effect on the separation and extraction of products.In this study,the main nitrogen sources in the medium,such as corn steep liquor,soybean meal hydrolysate and peptone,are approximately replaced with small-molecular amino acids,nucleosides and biotin using the method of equivalent substitution,and the ratio of the medium is optimized by orthogonal experiment and single factor experiment.The optimal addition amount of aspartic acid,glutamic acid,phenylalanine,tryptophan,succinic acid,biotin,guanosine,adenosine and inosine in L-tyrosine clear liquid medium is 2.2 g/L,2.4 g/L,1.5 g/L,1.5 g/L,1.5 g/L,1.0 mg/L,0.3 g/L,0.3 g/L,0.4 g/L respectively.The study shows that when L-tyrosine-producing strain E.coli TR03 is used for 35 h of fermentation in a 5 L fermentation tank,the OD_(600 nm)of clear liquid fermentation is 98,which is 18.1%higher than that of the control group.The yield of L-tyrosine is 55.2 g/L,which is 22.7%higher than that of the control group.The light transmittance of the supernatant of clear liquid fermentation is 47.8%,which is 20.9%higher than that of the control group.The seperation and extraction rate of clear liquid fermentation is 92.6%,which is 11.7%higher than that of the control group.The results show that the clear liquid fermentation could effectively enhance the strain's fermentation ability to produce L-tyrosine and improve the separation and extraction rate.