A novel Lactococcus lactisl-arabinose isomerase for d-tagatose production from lactose. (August 2022)

• Record Type: Journal Article
• Authors: Zhang, Susu; Xu, Zhenshang; Ma, Ming; Zhao, Guoyan; Chang, Runlei; Si, Hongli; Dai, Meixue
• Is Part Of: Food bioscience. Volume 48(2022)
• Publication Date: 2022-08
• Subjects: Lactose -- d-tagatose -- Lactic acid bacteria -- l-arabinose isomerase -- β-d-galactosidase; Food -- Biotechnology -- Periodicals; Food -- Research -- Periodicals; Aliments -- Biotecnologia -- Revistes; Aliments -- Investigació -- Revistes; Food -- Biotechnology; Food -- Research; Revistes electròniques; Periodicals; 664.005
• DOI: 10.1016/j.fbio.2022.101765
• Languages: English
• ISSNs: 2212-4292

Abstract

Abstract: 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. These β-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. thermophilus β-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. Graphical abstract: Image 1 Highlights: A new strain producing d -tagatose was isolated and identified as L. lactis X-18. Different β-d -galactosidases were co-expressed with AraA to produce d -tagatose. E. coli AI-d3 had the maximal production. The conversion rate from lactose was 42.4%, and the productivity was 4.28 g/L/h.