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Screening of the Dextran-producing Bacterium, Leuconostoc mesenteroides B4, in the Intestines of Largemouth Bass (Micropterus salmoides)

  • Date:2017-12-31
  • Volume:25
  • No:2
  • Page:23-33
  • Auther: Mei-Ying Huang, Huei-Jen Ju, Liang-Wei Tseng and Jinn-Rong Hseu

This study was devoted to the screening of a dextran-producing bacterium in the intestines of fishes. The structure of the dextran produced by the bacterium was characterized, the content of the dextran was estimated, and the dextran-producing bacterium was identified. The results indicated the presence of one strain, B4, which was isolated from largemouth bass (Micropterus salmoides) and had a dextran-producing property. The strain B4 was cultured in a 20%-sucrose nutrient medium. The amount of dextran produced by the strain B4 was 50 mg/ml after 48 hr of incubation at 28°C. The molecular weight of the dextran was 9.5 × 105 Da. The hydrolysate derived from acid and heating treatments of the dextran was mainly glucose. In comparison with previous reports, the 1H NMR and 13C NMR spectra of the dextran showed that its structure was similar to those of other dextrans which containα(1-6)-linked backbones. Thus, the glucose polymer produced by the strain B4 was identified as dextran with α(1-6)-linked backbones that hadα(1-3) branches. The strain B4 was identified as Leuconostoc mesenteroides by partial 16S rRNA gene sequencing and named L. mesenteroides B4.