Cellulase-free-thermo-alkali-solvent-stable xylanase from Bacillus altitudinis DHN8: Over-production through statistical approach, purification and bio-deinking/ bio-bleaching potential

• Published in: Biocatalysis and agricultural biotechnology Vol. 12; pp. 220 - 227
• Main Authors: Adhyaru, Dharmesh N., Bhatt, Nikhil S., Modi, H.A., Divecha, Jyoti
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.10.2017
• Subjects: Bio-bleaching; Bio-deinking; Cellulase-free xylanase; Over-production; Purification; Response surface methodology; Cellulase-free xylanase; Purification; Bio-deinking; Response surface methodology; Over-production; Bio-bleaching
• ISSN: 1878-8181; 1878-8181
• DOI: 10.1016/j.bcab.2017.10.010

The present study shows over-production of cellulase-free xylanase using Bacillus altitudinis DHN8 followed by its purification and applications. Response surface methodology, especially Box-Behnken Design was used to improve the enzyme yield by optimizing submerged fermentation conditions. Statistically optimized fermentation conditions to achieve higher xylanase production (492IU/mL) were sorghum straw 1.0%, inoculum size 3.0%, incubation time 48h, temperature 32°C, agitation speed 200rpm and gelatin 0.37%. Under these conditions, the resulted enzyme activity was two-fold high compared to the activity (245IU/mL) resulted after one-factor-at-a-time optimization. The purified xylanase was of high molecular weight (~98kDa) as revealed by SDS-PAGE. It showed optimum activity between 45°C and 55°C and at pH 8.0. Various metals, modulators, and organic solvents further improved the activity of purified enzyme. In this study, the crude xylanase was used for (1) bio-deinking of hand-written office waste papers having blue ink and (2) bio-bleaching of carton pulp. In the first case, 56.3% deinking of waste papers was achieved whereas in the second case, Kappa number of carton pulp was reduced to 10.85. Both results are suggesting the potential of B. altitudinis xylanase for the bio-deinking and bio-bleaching. [Display omitted] •Cellulase-free xylanase was over-produced from Bacillus altitudinis DHN8.•Statistical optimization through BBD has improved the xylanase yield markedly.•Very rare high molecular weight and robust xylanase was purified in active form.•Application opportunities of xylanase in bio-deinking and bio-bleaching.