Xylanase J (XynJ) from alkaliphilic Bacillus sp. 41M-1 is an alkaline xylanase. The crystal structure has been solved with XynJ. Improvement of the alkaliphily of XynJ was attempted by amino acid substitutions. Reinforcing the characteristic salt bridge in the catalytic cleft and introducing excess Arg residues on the protein surface shifted the optimum pH of the wild-type enzyme from 8.5 to 9.5.

https://www.tandfonline.com/doi/pdf/10.1271/bbb.80869

Improvement of alkaliphily of Bacillus alkaline xylanase by introducing amino acid substitutions both on catalytic cleft and protein surface.

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 (492 IU/mL) were sorghum straw 1.0%, inoculum size 3.0%, incubation time 48 h, temperature 32 °C, agitation speed 200 rpm and gelatin 0.37%. Under these conditions, the resulted enzyme activity was two-fold high compared to the activity (245 IU/mL) resulted after one-factor-at-a-time optimization. The purified xylanase was of high molecular weight (~98 kDa) 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.

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

Residue mutations of xylanase in Aspergillus kawachii alter its optimum pH.

Increase in the thermostability of GH11 xylanase XynJ from Bacillus sp. strain 41M-1 using site saturation mutagenesis.

Xylanase J of alkaliphilic Bacillus sp. strain 41M-1 contains a carbohydrate-binding module family 36 xylan-binding domain (XBD). Mutational analysis of the XBD revealed that Tyr237, Asp313, Trp317, and Asp318 were involved in Ca(2+)-dependent xylan-binding, and that Asp313 and Asp318 were especially important.

https://www.tandfonline.com/doi/pdf/10.1271/bbb.100730

A calcium-dependent xylan-binding domain of alkaline xylanase from alkaliphilic Bacillus sp. strain 41M-1.

Xylanase is an enzyme that catalyzes the hydrolysis of xylan, a β-1,4-linked xylose polymer Alkaliphilic Bacillus sp strain 41M-1 secretes a xylanase (xylanase J) that has an alkaline pH optimum Xylanase J is a multidomain enzyme and consists of two functional domains: a family 11/G catalytic domain and a non-catalytic xylan-binding domain The xylan-binding domain bound to xylan and enhanced catalytic activity of the adjacent catalytic domain Mutational analyses revealed some amino acid residues that contribute to catalytic activity, alkaliphily and xylan-binding activity of xylanase J

Satoshi Nakamura

Papers

Structure and function of a multidomain alkaline xylanase from alkaliphilic Bacillus sp. strain 41M-1