Xylanase production using agro-residue in solid-state fermentation from Bacillus pumilus ASH for biodelignification of wheat straw pulp.

Two stage statistical design was used to optimize xylanase production from Bacillus pumilus ASH under solid-state fermentation. Initially, Plackett-Burman designing (PB) was used for the selection of crucial production parameters. Peptone, yeast extract, incubation time, moisture level and pH were found to be the crucial factors for the xylanase production. Crucial variables were further processed through central composite designing (CCD) of response surface methodology (RSM) to maximize the xylanase yield. Each significant factor was investigated at five different levels to study their influence on enzyme production. Statistical approach resulted in 2.19-fold increase in xylanase yield over conventional strategy. The determination coefficient (R (2)) as shown by analysis of variance (ANOVA) was 0.9992, which shows the adequate credibility of the model. Potential of cellulase-free xylanase was further investigated for biobleaching of wheat straw pulp. Xylanase aided bleaching through XCDED(1)D(2) sequence resulted in 20 and 17% reduction in chlorine and chlorine dioxide consumption as compared to control. Significant increase in pulp brightness (%ISO), whiteness and improvement in various pulp properties was also observed.