Properties of Mannanase and Xylanase from Alkaliphilic Bacillus firmus K-1 and Their Hydrolysis on Kraft Pulps

Abstract

Alkaliphilic Bacillus firmus K-1 produces not only mannanase but also xylanase when grown inalkaline galactomannan medium. The mannanase showed the optimum pH and temperature at 6.0and 50 °C respectively and was stable at pH 6.0 to 9.0 and 30 to 50 °C. The pH and temperatureoptima of the xylanase were 6.0 and 60 °C respectively and it showed the stability over a broad pHrange from 5.0 to 9.0 and 30 to 60 °C.

The hydrolysis of kraft pulps by crude enzyme from B. firmus K-1 which grown in galactomannanmedium was investigated. It was found that the hydrolysis of eucalyptus pulp was higher than thoseof sugarcane bagasse and pine pulps. The comparison between the action of several crude enzymesshowed that the action of crude enzyme from B. firmus K-1 which grown in galactomannan medium,in the hydrolysis of sugarcane bagasse was similar to that of crude enzyme of B. firmus K-1 whichgrown in xylan medium and greater than that of crude enzyme of Bacillus sp. C-1 which grown inxylan medium. However, the hydrolysis of eucalyptus and pine pulps by crude enzyme from B. firmusK-1 which grown on galactomannan was greater than those of other crude enzymes.

Keywords : Alkaliphilic Bacillus firmus K-1 / Mannanase / Pulp Hydrolysis / Xylanase