Purification and characterization of theromohalophilic chitinase producing by halophilic Aspergillus flavus isolated from Suez Gulf

Abstract

This study aimed at production of chitinase enzyme from marine waste. Out of 27 fungal isolates, Aspergillus flavus (AUMC 13576) obtained from El-Sokhna has proved to be the most potent strain for chitinase production with activity 620.54 U/l using colloidal chitin as carbon source. The enzyme was purified consecutively by ammonium sulphate precipitation, Sephadex G-100 gel filtration column and DEAE - Cellulose A52 ion exchanger chromatographic column. The molecular weight of purified chitinase was estimated to be 30 KDa by SDS-PAGE. The purified enzyme was exposed for different properties investigations. The purified chitinase gave the highest activity (1368.8 U/l) within temperature rang (60 °C) at optimum pH 7.5 and 0.9 g/l of the substrate concentration. The kinetic measurements as Km and Vmax values of the enzyme were determined to be 0.18 g chitin/ml and 274.31 U/l, respectively. The enzyme showed thermal stability at 50 °C for 15 min. in salinity concentrations (NaCl) up to 0.8 M. Among different tested heavy metals, MnCl2 and FeSO4 boosted the activity positively. These results indicate the potential of mesophilic A. flavus (AUMC 13576) in the production of chitinases employing shrimp as an ideal substrate. Keywords: Aspergillus flavus (AUMC 13576), Chitinase, Purification, Metal ions