Oligosaccharides Production by Dextransucrase of Streptococcus bovis

Abstract

Oligosaccharides production on presence of maltose as glycosylacceptor by dextransucrase of Streptococcus bovis No.148 isolated from bovine rumen was investigated. Oligosaccharides produced by S. bovis dextransucrase were in agreement with those produced by Leuconostoc mesenteroides NRRL B-512 on the paper chromatogram. The trisaccharide (MG-1), the tetrasaccharide (MG-2), and the pentasaccharide (MG-3) was identified as 4-α-isomaltosyl-D-glucose, 4-α-isomaltotriosyl-D-glucose, and 4-α-isomaltotetraosyl-D-glucose, respectively. The oligosaccharides production was influenced by the presence of certain salts. Cobaltous chloride stimulated the MG-1 production, while depressed the MG-3 production. Calcium chloride and CuSO₄ depressed the MG-1 production, and stimulated the MG-3 production. Influence of maltose as acceptor on the oligosaccharides production was examined on the reaction mixture of 5% sucrose. It was found that the pattern of oligosaccharides production was controlled by the change of molar ratio of sucrose and maltose. When the molar ratio of maltose per sucrose was lower than 0.05, MG-3 and higher DP of oligosaccharides were produced. On the other hand, when the molar ratio was higher than 1.0, MG-1 was produced mainly. The calculated yield of MG-1 for consumed sucrose was about 78% of the molar ratio of maltose per sucrose at 4.0.