Thermophilic Alkaline Xylanase from Newly Isolated Alkaliphilic and Thermophilic<i>Bacillus</i>sp. Strain TAR-1

Abstract

Alkaliphilic and thermophilic Bacillus sp. strain TAR-1, isolated from soil, produced a xylanase extracellularly. The xylanase was most active over a pH range of 5.0 to 9.5 at 50°C. Optimum temperatures of the crude xylanase preparation were 75°C at pH 7.0 and 70°C at pH 9.0. Zymogram analyses of the culture supernatant showed that the molecular mass of the xylanase was 40 kDa and the isoelectric point was pH 4.1. The predominant products of xylan hydrolysate were xylobiose, xylotriose, and higher oligosaccharides, indicating that the enzyme was an endoxylanase. Production of the thermophilic alkaline xylanase was induced by xylan and xylose, but was repressed in the presence of glucose.