State Key Laboratory of Materials-Oriented Chemical Engineering, College of Biotechnology and Pharmaceutical Engineering, Nanjing Tech University, Nanjing 211800, PR China; Jiangsu National Synergetic Innovation Center for Advanced Materials (SICAM), Nanjing Tech University, Nanjing 211800, PR China.
State Key Laboratory of Materials-Oriented Chemical Engineering, College of Biotechnology and Pharmaceutical Engineering, Nanjing Tech University, Nanjing 211800, PR China.
Ultrason Sonochem. 2018 Apr;42:11-17. doi: 10.1016/j.ultsonch.2017.11.002. Epub 2017 Nov 2.
d-Tartaric acid has wide range of application in the pharmaceutical industry and scarcely exists in nature. In this study, cis-epoxysuccinate hydrolase (CESH)-containing Escherichia coli was used to perform whole-cell bioconversion of cis-epoxysuccinate (CES) to D-tartaric acid and the catalytic efficiency was investigated by ultrasound treatment. The bioconversion rate of CES sodium reached 70.36% after 60 min treated after ultrasound, which is 3-fold higher than that in the control. The specific rate could be further improved by 2-fold after 5 repeated batches compared with the first one, however, the specific rate gradually decreased with the increase of repeat batches (>5 batches). The CESH from Bordetella sp. BK-52 was a typical Michaelis-Menten enzyme with V and K values of 28.17 mM/h/g WCW (wet of cell weight) and 30.18 mM, respectively. The process for the d-tartaric acid bioconversion, which consisted of 102.31 g/L CES sodium, 8.78 mg/mL whole cell and ultrasound power of 79.36 W, is further optimized using response surface methodology. The specific rate finally reached 194.79 ± 1.78 mM/h/g WCW under the optimal conditions. Furthermore, the permeability of inner and outer membrane was improved approximately 1.6 and 1.4-fold after ultrasound treatment, respectively, which may be a crucial factor for improvement of the bioconversion efficiency.
酒石酸在制药工业中有广泛的应用，在自然界中几乎不存在。在本研究中，利用含有顺式-环氧琥珀酸水解酶（CESH）的大肠杆菌进行顺式-环氧琥珀酸（CES）的全细胞生物转化，并用超声处理考察其催化效率。超声处理 60min 后，CES 钠的转化率达到 70.36%，是对照的 3 倍。与第一个批次相比，经过 5 次重复批次处理后，比速率可进一步提高 2 倍，但比速率随着重复批次的增加（>5 批次）而逐渐降低。来自博德特氏菌 BK-52 的 CESH 是一种典型的米氏酶，V 和 K 值分别为 28.17mM/h/gWCW（细胞湿重）和 30.18mM。包含 102.31g/L CES 钠、8.78mg/mL 全细胞和 79.36W 超声功率的 d-酒石酸生物转化过程，进一步采用响应面法进行优化。在最佳条件下，比速率最终达到 194.79±1.78mM/h/gWCW。此外，超声处理后内膜和外膜的通透性分别提高了约 1.6 倍和 1.4 倍，这可能是提高生物转化效率的关键因素。
