Production and partial characterization of endoglucanase by Thermothelomyces heterothallicus PA2S4T and its application in biopolishing of denim jeans

Abstract

Most enzymes used in industry originate from microorganisms, such as endoglucanases that degrade cellulose. In this context, Thermothelomyces heterothallicus is a thermophilic filamentous fungus capable of producing substantial amounts of this enzyme. This study aimed to produce, purify, and characterize an endoglucanase from the novel strain of T. heterothallicus PA2S4T, utilizing orange peel as a carbon source, and applying this enzyme to denim fabric. Optimization of enzymatic production through experimental design yielded the best results for endoglucanases at the lowest temperature (28 °C) and shortest cultivation time (60 h), using the highest concentration of orange peel (4.2%), resulting in an endoglucanase activity of 61 U.mL⁻¹. Following purification steps, sample isolation was confirmed by observing a single band on SDS-PAGE at a molecular weight of 36.3 kDa. The enzymatic reaction exhibited an optimal pH of 7.0, with stability over a wide pH range (from 3.0 to 8.0). The enzyme showed optimal activity at 50 °C and remained thermally stable up to this temperature. Application of the enzyme in the bio-polishing step of denim jeans manufacturing, at concentrations of 1–5 U.mL⁻¹, resulted in weight losses of 2–5%. The best weight loss results were found after 12 h of treatment, at 50 ºC and pH 5.0. Additionally, the scanning electron microscopy showed that 2 and 5 U.mL⁻¹ of enzyme improved appearance of denim fabric by removing protuberances and irregularities compared to untreated fabric.