Rheology and characterization of a low viscosity emulsifying exopolymer from desert borne <i style="mso-bidi-font-style: normal">Nostoc calcicola</i>

Abstract

<i style="mso-bidi-font-style:normal">Nostoc calcicola</i> produced profuse amount of polysaccharidic exopolymer under P limited conditions. The exopolymer showed a truly pseudoplastic, non-Newtonian, time independent behaviour with good recovery after shear. It was composed of D-ribose, D-arabinose, L-rhamnose, L-fucose, D-xylose, D-mannose, D-glucose, D-galactose and 3-methyl-D-arabinose. IR spectra showed bands at ~1250 and 820 cm^-1, characteristic of sulphate residue. The exopolymer showed good emulsifying and antimicrobial activity. It absorbed 282 g H₂O.g^-1 exopolymer. The possible applications of the exopolymer in pharmaceutical, food and oil recovery industry have been discussed.