Single-step purification and characterization of an extreme halophilic, ethanol tolerant and acidophilic xylanase from Aureobasidium pullulans NRRL Y-2311-1 with application potential in the food industry

Abstract

An extracellular xylanase from Aureobasidium pullulans NRRL Y-2311-1 produced on wheat bran was purified by a single-step chromatographic procedure. The enzyme had a molecular weight of 21.6kDa. The optimum pH and temperature for xylanase activity were 4.0 and 30-50°C, respectively. The enzyme was stable in the pH range of 3.0-8.0. The inactivation energy of the enzyme was calculated as 218kJmol^-1. The xylanase was ethanol tolerant and kept complete activity in the presence of 10% ethanol. Likewise, it retained almost complete activity at a concentration range of 0-20% NaCl. In general, the enzyme was resistant to several metal ions and reagents. Mg²⁺, Zn²⁺, Cu²⁺, K¹⁺, EDTA and β-mercaptoethanol resulted in enhanced xylanase activity. The K_m and V_max values on beechwood xylan were determined to be 19.43mgml^-1 and 848.4Uml^-1, respectively. The enzyme exhibits excellent characteristics and could, therefore, be a promising candidate for application in food and bio-industries.

Keywords: Aureobasidium pullulans NRRL Y-2311-1; Biochemical characterization; Extremophilic xylanase; Single-step purification; Thermodynamic parameters.