Characterization of xylanase from microbulbifer sp. CL37 for industrial applications

Xylan is the most abundant sugar in hemicellulose and can be found in plant biomass. Xylanase produced by microorganisms such as bacteria can be used in industries such as paper and pulp for deinking process. A halophilic bacterium, Microbulbifer sp. strain CL37, was previously isolated from mangrove sediment and its extracellular xylanase was characterized in this study. Strain CL37 is a motile Gram-negative bacterium with rod shape, catalase, and oxidase positive. Strain CL37 also can hydrolyse xylan, casein, gelatin, Tween 20, Tween 40, Tween 60 and Tween 80. Cells are sensitive to gentamicin, tetracycline, polymyxin B, doxycycline, minocycline and rifampicin. The xylanase exhibited maximum activity at 70°C, pH7, and absent of NaCl. The xylanase remained activity up to 14% (w/v) NaCl indicates it is halotolerant xylanase. The xylanase activity was enhanced in the presence of Al3+, Ca2+, Co2+, Cu+, Cu2+, Fe2+, Fe3+, Mn2+, and Zn2+ (112-175% relative activity), stable in K+, Na+, and Ni2+ (>80% relative activity), but reduced in the presence of Mg2+ (59% relative activity). The xylanase activity also enhanced in the presence of acetone (127% relative activity) and remains stable (>70% relative activity) in most of the tested detergent constituents. Xylanase is also compatible with commercial detergents such as Top®, Dynamo®, Sunlight®, Glo®, Breeze® and Dixan®. Evaluation of the enzymatic deinking activity demonstrated that xylanase from strain CL37 has the ability to detach the adsorbed ink particle from the surface of paper. Collectively, xylanase from Microbulbifer sp. strain CL37 could have potential in various applications, such as detergent formulation, lignocellulolytic biofuel production and paper deinking