文献类型：期刊文献

英文题名：A green-by-design bioprocess for l-carnosine production integrating enzymatic synthesis with membrane separation

作者：Yin, Dong-Ya[1];Pan, Jiang[1];Zhu, Jie[2];Liu, You-Yan[3];Xu, Jian-He[1]

机构：[1]East China Univ Sci & Technol, State Key Lab Bioreactor Engn, Shanghai 200237, Peoples R China;[2]East China Univ Sci & Technol, Sch Chem & Mol Engn, Shanghai 200237, Peoples R China;[3]Guangxi Univ, Coll Chem & Chem Engn, Nanning 530004, Peoples R China

年份：2019

卷号：9

期号：21

起止页码：5971

外文期刊名：CATALYSIS SCIENCE & TECHNOLOGY

收录：;EI(收录号：20194607672084);WOS:【SCI-EXPANDED(收录号:WOS:000493075200005)】；

基金：This work was financially sponsored by the National Key Research and Development Program of China (2016YFA0204300), the National Natural Science Foundation of China (No. 21536004, 21776085 & 21871085), and the Fundamental Research Funds for the Central Universities (222201714026 & WF1714026).

语种：英文

外文关键词：Amino acids - Manganese compounds - Peptides - Escherichia coli - Metals - Substrates - Batch data processing - Microfiltration - Mixtures

摘要：l-Carnosine (l-Car, beta-alanyl-l-histidine) is a bioactive dipeptide with important physiological functions. Direct coupling of unprotected beta-Ala (beta-alanine) with l-His (l-histidine) mediated by an enzyme is a promising method for l-Car synthesis. In this study, a new recombinant dipeptidase (SmPepD) from Serratia marcescens with a high synthetic activity toward l-Car was identified by a genome mining approach and successfully expressed in Escherichia coli. Divalent metal ions strongly promoted the synthetic activity of SmPepD, with up to 21.7-fold increase of activity in the presence of 0.1 mM MnCl2. Higher temperature, lower pH and increasing substrate loadings facilitated the l-Car synthesis. Pilot biocatalytic syntheses of l-Car were performed comparatively in batch and continuous modes. In the continuous process, an ultra-filtration membrane reactor with a working volume of 5 L was employed for catalyst retention. The dipeptidase, SmPepD, showed excellent operational stability without a significant decrease in space-time yield after 4 days. The specific yield of l-Car achieved was 105 g(Car) g(catalyst)(-1) by the continuous process and 30.1 g(Car) g(catalyst)(-1) by the batch process. A nanofiltration membrane was used to isolate the desired product l-Car from the reaction mixture by selectively removing the excess substrates, beta-Ala and l-His. As a result, the final l-Car content was effectively enriched from 2.3% to above 95%, which gave l-Car in 99% purity after ethanol precipitation with a total yield of 60.2%. The recovered substrate mixture of beta-Ala and l-His can be easily reused, which will enable the economically attractive and environmentally benign production of the dipeptide l-Car.