Interaction of Cationic Dye with Bacterial Cell Surface Polysaccharide from Klebsiella K40

Interaction of cationic dye pinacyanol chloride with bacterial cell surface capsular polysaccharide isolated from Klebsiella K40 has been spectrophotometrically Investigated. The capsular polysaccharide of Klebsiella K40 is a heteroglycan which consists of pentasaccharide repeating units comprising one residue each of unsubstituted mannose, 4-substituted glucuronic acid, 3-substituted galactose, 2, 4-disubstituted rhamnose, and 2-substituted rhamnose. It Induces a metachromatic blue shift in the visible spectrum of the pinacyanol chloride from 600 nm to 500 nm. The metachromatic spectral changes have been studied during interaction of the dye cation with the polyanion at different polymer/dye molar ratios. A stochiometry of 11 for the polymer/dye has been found to exist in the polyanion-dye compound. The complete reversal of polymer-induced metachromasy has also been observed by the addition of ethanol and urea.