为提高L-苯丙氨酸生产效率,降低发酵成本,该研究将FeSO4·7H2O、MnSO4·H2O等用量进行进一步优化,去除了维生素H的添加,并引进了磷酸吡哆醛、维生素B2等微量元素,通过单因素试验、正交试验、发酵罐验证实验,以关键酶活、L-苯丙氨酸产量、糖酸转化率、副产物含量等为指标,最终确定了适合L-苯丙氨酸发酵的微量元素种类为及用量分别为:CaCl2·2H2O 1.1×10-2 g/L、CuSO4·5H2O 4.7×10-4 g/L、CoCl2·6H2O 6×10-3 g/L、ZnSO4 6×10-4g/L、FeSO4·7H2O 2.8×10-2 g/L、MnSO4·H2O 1.4×10-2 g/L、NiCl2·6H2O 6.06×10-3 g/L、PLP 9.5×10-3 g/L、维生素B2 6×10-3 g/L。最终优化后生物量为122.8,L-苯丙氨酸产量为85.4 g/L,糖酸转化率为26.3%,分别较不添加微量元素的对照组提高了17.5%、51.4%、18.6%,同时减少了副产物的种类和生成量,提高了关键酶活力。最终结果表明,优化后的微量元素种类及用量提高了L-苯丙氨酸的产量、糖酸转化率,提高了产品竞争力。
In order to improve the production efficiency of L-phenylalanine and reduce the cost of fermentation, the dosage of FeSO4·7H2O/MnSO4·H2O was further optimized. Biotin H was no longer added, and trace elements such as pyridoxal phosphate and vitamin B2 were added. Through single factor experiment, orthogonal test and fermentor verification experiment, the key enzyme activity, L-phenylalanine yield, sugar-acid conversion rate and by-product content were taken as indexes. Finally, the types and dosage of trace elements which is suitable for L-phenylalanine fermentation were determined as follows: CaCl2·2H2O 1.1×10-2 g/L, CuSO4·5H2O 4.7×10-4 g/L,CoCl2·6H2O 6×10-3 g/L, ZnSO4 6×10-4 g/L, FeSO4·7H2O 2.8×10-2 g/L, MnSO4·H2O 1.4×10-2 g/L, NiCl2·6H2O 6.06×10-3 g/L, PLP 9.5×10-3 g/L, vitamin B2 6×10-3 g/L. The final biomass was 122.8, the yield of L-phenylalanine was 85.4 g/L, and the conversion rate of sugar and acid was 26.3%, which was 17.5%, 51.4% and 18.6% higher than that of the control group without trace elements, respectively. At the same time, the variety and production of by-products were reduced, and the key enzyme activity was improved. The final result showed that the optimized type and dosage of trace elements could increase the sugar-acid conversion rate of L-phenylalanine and improve the competitiveness of the product.
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