Efficient biosynthesis of lactosucrose from sucrose and lactose by the purified recombinant levansucrase from Leuconostoc mesenteroides B-512 FMC

Publication Type

Journal contribution (peer reviewed)

Authors

Li, W.; Yu, S.; Zhang, T.; Jiang, B.; Stressler, T.; Fischer, L. and Mu, W.

Year of publication

2015

Published in

Journal of Agricultural and Food Chemistry

DOI

10.1021/acs.jafc.5b03648

Lactosucrose, a rare trisaccharide formed from sucrose and lactose by enzymatic transglycosylation, is a kind of indigestible carbohydrate with good prebiotic effect. Microbial levansucrase is the most used biocatalyst for lactosucrose production, which produces lactosucrose via transfructosylation from sucrose to lactose. However, most of the previous works focused on the lactosucrose production by the crude enzyme or whole cells harboring levansucrase activity. In this study, lactosucrose biosynthesis was efficiently carried out by a purified levansucrase from Leuconostoc mesenteroides B-512. The target gene was cloned and expressed in Escherichia coli, and the recombinant enzyme was purified to homogeneity by nickel affinity and gel filtration chromatography. The structure of the formed lactosucrose from sucrose and lactose was determined by nuclear magnetic resonance analysis. The effects of pH, temperature, substrate concentration, substrate ratio, and enzyme amount on lactosucrose biosynthesis were studied in detail, and the optimized conditions were determined to be pH 6.5, 50 °C, 27% (W/V) sucrose, 27% (W/V) lactose, and 5 U mL-1 of the purified recombinant enzyme. Under the optimized reaction conditions, the maximal lactosucrose yield reached 224 g L-1 after reaction for 1 h, which was the second highest yield ever reported. Therefore, L. mesenteroides levansucrase could be considered as a potential candidate for future industrial production of lactosucrose.