A mutant strain of Leuconostoc mesenteroides B-1355 producing a glucosyltransferase synthesizing ?(1?2) glucosidic linkages

• Published in: Journal of industrial microbiology & biotechnology 1998-08, Vol.21 (1-2), p.37-45
• Main Authors: Smith, M R, Zahnley, J C, Wong, R Y, Lundin, R E, Ahlgren, J A
• Format: Article
• Language: English
• Subjects: Bacteria; Bacteriology; Leuconostoc mesenteroides; Mutants; NMR; Nuclear magnetic resonance; Sucrose
• ISSN: 1367-5435; 1476-5535
• DOI: 10.1038/sj.jim.2900558

A mutant strain (R1510) of Leuconostoc mesenteroides B-1355 was isolated which synthesized primarily an insoluble polysaccharide and little soluble polysaccharide when grown in sucrose-containing medium. Glucose or sucrose cultures of this strain produced a single intense band of GTF-1 activity of 240kDa on SDS gels, and a number of faint, smaller bands. Oligosaccharides synthesized by strain R1510 from methyl-α-D-glucoside and sucrose included a trisaccharide whose structure contained an α(1[arrow right]2) glucosidic linkage. This type of linkage has not been seen before in any products from strain B-1355 or its mutant derivatives. The structure of the purified trisaccharide was confirmed by ^sup 13^C-nuclear magnetic resonance. The insoluble polysaccharide also contained α(1[arrow right]2) branch linkages, as determined by methylation analysis, showing that synthesis of the linkages was not peculiar to methyl-α-D-glucoside. GTF-1, which had been excised with a razor blade from an SDS gel of a culture of the parent strain B-1355, produced the same trisaccharides as strain R1510, showing that GTF-1 from the wild-type strain was the same as GTF-1 from strain R1510. Mutant strains resembling strain R1510, but producing a single intense band of alternansucrase (200kDa) instead of GTF-1 were also isolated, suggesting that mutations may be generated which diminished the activities for any two of the three GTFs of strain B1355 relative to the third. Strain R1554 produced a soluble form of alternansucrase, while strain R1588 produced a cell-associated form. The mechanism(s) by which specific GTFs become associated with the cells of L. mesenteroides was not explored.[PUBLICATION ABSTRACT]