Ultrasound-assisted degradation of a new bacterial exopolysaccharide WL-26 from Sphingomonas sp.
Ultrasonic degradation of a new exopolysaccharide WL-26 from Sphingomonas sp. was made over the frequency range 200 to 1200 Hz and polymer concentrations of 3, 5, 10 and 20 g/L using high performance anion exchange pulsed-amperometric detection chromatography (HPAEC–PAD) and infrared spectroscopy. Sonication was more efficient with less concentrated polysaccharide solutions, high ultrasonic frequency, long duration of ultrasonic irradiation and degradation continued until a limiting molecular weight was attained. Results show that HPAEC–PAD revealed WL-26 to be an acidic polysaccharide composed of rhamnose, glucose, mannose, galactose and glucuronic acid in the molar ratio of 10:9:3:1:3 distinctly different from welan gum which does not contain galactose.
Key words: Exopolysaccharide WL-26, ultrasonic degradation, infrared spectroscopy.