Characterization of a thermostable levansucrase from Bacillus sp TH4-2 capable of producing high molecular weight levan at high temperature

A thermoactive and thermostable levansucrase was purified from a newly isolated thermophilic Bacillus sp. from Thailand soil. The purification was achieved by alcohol precipitation, DEAE-Cellulose and gel filtration chromatographies. The enzyme was purified to homogeneity as determined by SDS-PAGE, and had a molecular mass of 56 kDa. This levansucrase has some interesting characteristics regarding its optimum temperature and heat stability. The optimum temperature and pH were 60 degreesC and 6.0, respectively. The enzyme was completely stable after treatment at 50 degreesC for more than 1 h, and its activity increased four folds in the presence of 5 mM Fe2+. The optimum temperature for levan production was 50 degreesC. Contrary to other levansucrases, the one presented in this study is able to produce high molecular weight levan at 50 degreesC. (C) 2002 Elsevier Science B.V. All rights reserved.