Production of xylanase under submerged fermentation from Bacillus firmus HS11 isolated from Sikkim Himalayan region

Abstract

Xylanase producing microorganisms isolated from high altitude soil show activity at broad window of temperature, and can have variety of industrial applications. Here, we explored production of xylanase under submerged fermentation from Bacillus firmus HS11 isolated from Sikkim Himalayan region. We isolated 472 bacterial strains high altitude soil samples (1120-4272 m) from Sikkim and screened for xylanase production. Among them five strains that showed higher xylanase activity were identified by 16s rRNA gene sequence analysis. comparatively, Bacillus firmus HS11 showed highest activity at 10, 37 and 50°C, and was chosen for optimization experiment. B. firmus HS11 showed xylanase activity of 3.35 U/mg of protein at 37°C and retained 32.43% activity at 10°C and had 79.82% higher activity at 50°C. Optimization of nutrient composition for submerged fermentation of B. firmus HS11 was carried out by combination of Plackett-Burman design and response surface methodology. The optimized media component for xylanase production by submerged fermentation by B. firmus HS11 is beechwood xylan 0.8% (w/v), MgSO₄ 0.04% (w/v), CaCl₂0.04% (w/v), peptone 0.1% (w/v), NaCl 0.3% (w/v) and yeast extracts 0.01% (w/v), resulting in enhancement of xylanase production by 7.4 folds. Xylanase having activity at broad range of temperature including lower temperature can have application in food industry.