Affiliation:
1. Centre for Carbohydrate Bioprocessing (CCB), TNO-University of Groningen, P.O. Box 14, 9750 AA Haren, The Netherlands, and Department of Microbiology, Groningen Biomolecular Sciences and Biotechnology Institute (GBB), University of Groningen, Kerklaan 30, 9751 NN Haren, The Netherlands
Abstract
ABSTRACT
Fructansucrase enzymes polymerize the fructose moiety of sucrose into levan or inulin fructans, with β(2-6) and β(2-1) linkages, respectively. The probiotic bacterium
Lactobacillus johnsonii
strain NCC 533 possesses a single fructansucrase gene (open reading frame AAS08734) annotated as a putative levansucrase precursor. However,
13
C nuclear magnetic resonance (NMR) analysis of the fructan product synthesized in situ revealed that this is of the inulin type. The
ftf
gene of
L. johnsonii
was cloned and expressed to elucidate its exact identity. The purified
L. johnsonii
protein was characterized as an inulosucrase enzyme, producing inulin from sucrose, as identified by
13
C NMR analysis. Thin-layer chromatographic analysis of the reaction products showed that InuJ synthesized, besides the inulin polymer, a broad range of fructose oligosaccharides. Maximum InuJ enzyme activity was observed in a pH range of 4.5 to 7.0, decreasing sharply at pH 7.5. InuJ exhibited the highest enzyme activity at 55°C, with a drastic decrease at 60°C. Calcium ions were found to have an important effect on enzyme activity and stability. Kinetic analysis showed that the transfructosylation reaction of the InuJ enzyme does not obey Michaelis-Menten kinetics. The non-Michaelian behavior of InuJ may be attributed to the oligosaccharides that were initially formed in the reaction and which may act as better acceptors than the growing polymer chain. This is only the second example of the isolation and characterization of an inulosucrase enzyme and its inulin (oligosaccharide) product from a
Lactobacillus
strain. Furthermore, this is the first
Lactobacillus
strain shown to produce inulin polymer in situ.
Publisher
American Society for Microbiology
Subject
Ecology,Applied Microbiology and Biotechnology,Food Science,Biotechnology
Cited by
80 articles.
订阅此论文施引文献
订阅此论文施引文献,注册后可以免费订阅5篇论文的施引文献,订阅后可以查看论文全部施引文献