Isolation and Characterization of Exopolysaccharide Produced by Indigenous Soil Bacterium Bacillus Strain CMG1403

Some of physical and structural characteristic features of exopolysaccharide (EPS) produced by indigenous soil bacterium Bacillus strain CMG1403 were studied by general analytical methods . EPS was isolated as high molecular weight, homogeneously white polymer containing 85.85% organic and 12.78% moisture content. In organic solvents such as methanol , ethanol, isopropanol and acetone, it exhibited flocculant propert ies whereas in distilled water and alkaline solution (0.1-1% NaOH) showed suspension gelling propert ies on stirring . Quantitatively, 92.13% hexoses as neutral sugars and 7.86% uronic acids were detected in purified EPS. This was confirmed by paper chromatograph ic separation of acid hydrolysate, that EPS produced by CMG1403 was an acidic heteropolysaccharide containing glucuronic acid, galactose and mannose. Degree of polymerization of .these sugar units in EPS was estimated in terms of relative molecular weight, dispersed from 2x 104 - 25x 104 Da. This high molecular weight EPS was found to absorb 435 times more water than its own dry weight and also had the capacity to retain more than 40% of supplied water even at 60°C for 20 days . Further, bacterial and fungal strains test could use the purified EPS as sole carbon source and their growth could not be inhibited. So it may be deduced that it is biodegradable and does not display in vitro antimicrobial activity. Therefore, based on these results, acidic heteropolysaccharide produced by Bacillus strain CMG1403 could be suggested to serve as non-toxic, biodegradable and environmental friendly water absorbent and thickening agent