Abstract:
The aims of this research were to modify the polysaccharide purification method of Moonmangmee, et al. (2002a) and characterize the purified polysaccharide from Acetobacter lovanensis IFO 3284 R strain. Cells were crushed by French Pressure Cell Press. After removing cell debris by centrifugation, cell-free extract was obtained. Solubilization of cytoplasmic membrane component was performed with 2% Triton X-100 for 2 h. The solution was then dialyzed against 25 mM
Tris-HCl (pH 8.5) at 4 'C for 24 h. After centrifugation, the supernatant containing polysaccharide was then applied onto DEAE-cellulose column chromatography. Pooled polysaccharide containing fractions were collected, concentrated by ultrafiltration molecular weight cutoff 50,000 dalton and precipitatated with isopropanol. The polysaccharide was further purified with two successive
column chromatography, Sephacryl S-400 and Sephacryl S-500 column, respectively. The results showed that the purified polysaccharide obtained from the modified method had the same characteristics and properties as the polysaccharide prepared by mild condition (Moonmangmee et al., 2002a) having molecular mass of 700 kDa, which composed of two different types of monosaccharide, glucose and rhamnose in the molar ratio of 1:1. The optimum conditions for oligosaccharide preparation from purified polysaccharide of Acetobacter lovanensis IFO 3284 R strain found that the polysaccharide was successfully hydrolyzed in an aqueous 0.1 N trifluoroacetic acid at temperature of 90 'C for 5 h. Purification of various sizes of oligosaccharide was performed by applying onto Bio-Gel P4 connected with Bio-Gel P2 column chromatography.
Purified oligosaccharide was used to study in order to obtain the glycosyl linkage information by Methylation analysis and analyse the sugar derivatives consisting in purified oligosaccharide by Gas Chromatography-Mass Spectrometry. As the results, oligosaccharide peak no. 4 was consisting of the sugar derivatives of 3-linked-L-Rhap, terminal glucose, 2-terminal glucose and 2-linked-DGlup in the molar ratio of 1.7 : 5.6 : 1.0 : 4.0, respectively.