Effect of Proteins and Glycine on Thermal Stability of Alkaline Xylanase from Alkaliphilic Bacillus firmus K-1

Abstract

Effect of the addition of various concentrations of proteins and amino acid on the thermal stability ofthe alkaline xylanase from alkaliphilic Bacillus firmus K-1 was studied. The enzyme at the concentration of0.148 mg protein/ml gave the half-life of 3 h under the condition of 55 °C, pH 10. It was found thatincreasing bovine serum albumin (BSA) in the range of 0.5-2.0% (w/v) increased thermal stability of theenzyme. Whereas BSA at the concentration of 2.0% (w/v) gave the highest half-live of 9.8 h. On the otherhand, although the addition of casein and glycine in the range of concentrations of 0.5-2.0% (w/v) and 0.5-1.5 M, respectively, increased the stability of xylanase. However, thermal stability of the enzyme decreasedwhen the concentrations of casein and glycine increased. Casein and glycine at the concentrations of 0.5%(w/v) and 0.5 M gave the longest half-life at 8 and 7 h, respectively.

Keywords : Alkaliphilic Bacillus firmus / Alkaline Xylanase / Thermal Stability of XylanaseAbstract*Corresponding