Studies on a extracellular polysaccharide produced by bacteria isolated from river water.

In order to find new thickening agents or emulsifiers which possess uselful characteristics forfood industries, we attempted screening of microorganisms from soli and water. As a result, we found one bacterial strain which produced a large amount of extracellular polysaccharide from Sumida River in Tokyo. The strain was identified as Klebsiella pneumoniae in conformity to Bergey's Manual of Systematic Bacteriology (1984). The polysaccharide (BS-1) produced by this strain showed higher viscosity than known thickening agents such as xanthan gum, carrageenan and tragacanth gum. The viscosity of 1% (w/v) BS-1 at 20°C reached 7000cps under the shear rate of 1/S. Besides, BS-1 possessed a good property as an emulsifier. When we made emulsions of O/W=3/7 using several emulsifiers involving BS-1 and observed after 3 days of storage at room temperature, it was found that BS-1 stabilized the emulsion at the concentration of as low as 0.1% (w/v), and that the emulsion kept its creamy smoothness.