FLOW PROPERTIES OF HALOARCHAEAL POLYSACCHARIDES IN AQUEOUS-SOLUTIONS

The flow properties of the polysaccharides produced by Haloferax medit erranei(T) ATCC 33500 and its super mutant Haloferax mediterranei EPS+, R4 and EPS++ respectively, were investigated. The R4 repeating unit is a trisaccharide containing mannose and 2-acetamido-2-deoxyglucuron ic acid, ester sulphate groups are also present. In order to compare t he properties of both polymers viscosimetric measurements were carried out at different integration times and using different concentrations of polymer. Under the assayed experimental conditions no effect of th e time applying stress is detected for either polymer. A strong pseudo plastic behaviour is observed which is increased as the polymer concen tration rises. Differences in viscosity between both polymers are due to the different molecular weights. The correlation of the experimenta l data using a modification of the Cross model has given very good res ults. (C) 1998 Elsevier Science Ltd. All rights reserved.