Studies on the interaction of bacterial capsular polysaccharide-Klebsiella K16 with cationic dyes

The spectral studies of cationic dyes, pinacyanol chloride and acridine orange with bioploymer, Klebsiella K16 capsular polysaccharide (PK16) in aqueous media reveal many interesting phenomena. The polysaccharide induces metachromasy in the dye, resulting a blue shift from 600 to 490 nm. The stoichiometry and also thermodynamic parameters of the polymer/dye in the metachromatic compound and the effect of different solvent–cosolvent on its stability have been studied. Quenching of fluorescence of acridine orange by PK16 has added another evidence for the existence of the staggered aggregation of dye. In addition to this, the equivalent weight, chromotropic character, conformation of the biopolymer and the site of interaction between dye and Klebsiella K16 have been pointed out.