Cellulase-free thermostable alkaline xylanase from thermophilic and alkalophilic Bacillus sp JB-99

Abstract

The characterization of a partially purified, cellulase-free, thermostable alkaline xylanase from thermoalkalophilic Bacillus sp. JB-99 was investigated. The xylanase production was the highest when birchwood xylan was added to a medium containing finely powdered rice bran, showing 4,826 IU ml(-1) of activity for 15 h of incubation. The partially purified xylanase exhibited an optimum temperature and pH at 70degreesC and 10, respectively. The enzyme was stable at pH 5-11 at 50degreesC. The xylanase activity was strongly inhibited by Hg2+, while dithiothreitol, cysteine, and beta-mercaptoethanol enhanced the activity.