A novel Lactococcus lactis L-arabinose isomerase for D-tagatose production from lactose  

作　　者：Susu Zhang Zhenshang Xu Ming Ma Guoyan Zhao Runlei Chang Hongli Si Meixue Dai 

机构地区：[1]College of Life Science,Shandong Normal University,Jinan,250014,PR China [2]State Key Laboratory of Biobased Material and Green Papermaking,Qilu University of Technology,Shandong Academy of Science,Jinan,250353,PR China [3]Shandong Provincial Key Laboratory of Microbial Engineering,Department of Bioengineering,Qilu University of Technology,Shandong Academy of Science,Jinan,250353,PR China

出　　处：《Food Bioscience》2022年第4期339-348,共10页食品生物科学（英文）

基　　金：supported by Natural Science Foundation of Shandong Province(ZR2021QC160);Key Research and Development Program of Shandong Province(2020CXGC010602);Science and Technology Support Plan for Young People in Colleges and Universities of Shandong Province(2020KJE005).

摘　　要：A new strain of Lactococcus lactis producing D-tagatose was isolated and identified.Its L-arabinose isomerase coding gene was cloned and expressed in Escherichia coli BL21(DE3).The optimal temperature and pH of the purified enzyme were 50◦C and 8.0.To produce D-tagatose from lactose,β-D-galactosidases from Lc.Lactis,Lactiplantibacillus plantarum,and Streptococcus thermophilus were further incorporated into E.coli by two strategies.Theseβ-D-galactosidases were fused to L-arabinose isomerase coupled with a peptide linker(GGGGS)3.Meanwhile,they were co-expressed with L-arabinose isomerase using pETDuet-1 vector.Among these recombinant strains,the cell co-expressing L-arabinose isomerase and S.thermophilusβ-D-galactosidase showed maximal activity.SDS-PAGE results confirmed that exogenous enzymes had the maximum soluble expression level in this strain.At the optimal condition,the conversion rate of D-tagatose from 300 g/L lactose achieved to 42.4%,and the volumetric productivity reached 4.28 g/L/h at 15 h.This research established a highly efficient biotransformation system to produce D-tagatose from lactose.

关 键 词：LACTOSE D-TAGATOSE Lactic acid bacteria L-arabinose isomerase Β-D-GALACTOSIDASE 

分 类 号：TS20[轻工技术与工程—食品科学]