Optimization and extraction of an alkaline xylanase produced of Bacillus pumilus

Most of the xylanases commercially available produced by fungi are active at neutral or acidic pH and their optimum temperature for activity is below 45 degrees C. Extremophilic xylanases which are active at alkaline conditions have great potential for industrial application as a bleaching process without any need for changes in pH. The best composition of the culture media for maximisation of the alkaline xylanase produced by Bacillus pumilus able to hydrolyse birchwood xylan at pH 10 at 45 degrees C was 3% xylan and 0.6% peptone, the highest enzyme activity was around 33.0U/mL. The enzyme from crude fermentation broth was extracted in aqueous two phase systems (ATPS). An experimental design was used to study the effects of polyethyleneglicol (PEG) molecular weight (MW) and PEG, phosphate and sodium chloride concentrations on xylanase recovery and purification factor. A purification factor of 33 and a 98% enzyme recovery were achieved for the system containing 22% PEG 6,000, 10% K2HPO4 and 12% NaCl.