A halostable cellulase with a molecular mass of 29 kDa was purified from culture supernatants of the halophilic bacterium Salinivibrio sp. NTU-05 by way of the East Protein Liquid chromatography method and the biochemical properties of the halostable cellulase was studied. The enzyme was active over a range of 0-25% sodium chloride examined in culture broth. The optimum cellulase activity was observed at 5% sodium chloride. Results from the salinity stability test indicated 24% of enzyme activity was retained at 25% sodium chloride for 4 h. The enzyme was also shown to be slightly thermostable with 40% residual activity under 60 degrees C for 4 h. enzyme has a K-m of 3.03 mg/ml and a V-max of 142.86 mol/min/mg when tested using carboxymethyl-cellulose (CMC). The enzyme activity increased in the presence of K+, Mg2+, Na+ ions and decreased when Hg2+ ions were present. The deduced internal amino acid sequence of the Salinivibrio sp. NTU-05 cellulase showed similarity to the sequence of the glycoside hydrolase family protein. These are some of the novel characteristics that make this enzyme have potential applications in cellulose biodegradation. (C) 2009 Elsevier Inc. All rights reserved.