Production, purification, characterization and usage of a detergent additive of endoglucanase from isolated halotolerant Amycolatopsis cihanbeyliensis mutated strain Mut43

Abstract

The Amycolatopsis cihanbeyliensis Mut43, which is obtained by UV radiation, exhibited endoglucanase activity of 5.21 U/mL, which was ∼2.3-fold higher than that of the wild strain (2.04 U/mL). The highest enzyme activity was obtained after 3 days of incubation at 32 °C, pH 7.0, 150 rpm, and 6% NaCl in a liquid medium containing 1.5% (w/v) wheat straw (0.25 mm of particle size) and 0.6% (w/v) yeast extract. Enzyme activity was eluted as a single peak (gel filtration chromatography), and Sodium dodecyl sulfate–polyacrylamide gel electrophoresis (SDS–PAGE) analysis of the corresponding peak revealed a molar mass of 30 kDa. Zymogram analysis confirmed the presence of a single active endoglucanase component. The enzyme was purified to ∼21-fold, and the mean overall yield was ∼6%. The purified endoglucanase was active up to 80 °C and showed a half-life of 214 min at 60 °C in the absence of substrate at pH 8.0. The apparent Km value for the purified endoglucanase was 0.70 mg/mL, while the Vmax value was 6.20 Units/μg. Endoglucanase activity was reduced (25%) by treatment with 30 U of proteinase K/mg. The addition of Mg+2 and Ca+2 (5 mM) enhanced endoglucanase activity. Additionally, endoglucanase activity in the presence of 5 mM SDS or organic solvents was 75 and 50% of maximum activity, respectively. The high levels of enzyme production from A. cihanbeyliensis Mut43 achieved under batch conditions, coupled with the temperature stability, activity over a broad pH range, relatively high stability (70–80%) in the presence of industrial laundry detergents and storage half-lives of 45 days at +4 °C and 75 days at −20 °C signify the suitability of this enzyme for industrial applications as detergent additive.