Production, purification and characterisation of proteases from whey by some fungi

Abstract

The results regarding the production of proteases fromAspergillus niger andAspergillus terreus revealed that different nitrogen complements induced different growth and enzyme productivity depending on the individual organism, nature of cosupplement and/or concentration. The two steps fermentation process increased the yield of fungal biomass and proteases. Proteases were isolated and purified fromA. niger andA. terreus with specific activity of 179.0 and 294.7 U mg−1 protein, respectively. The purification fold values were 28.9 and 81.9 from the two organisms in the same order. The Vmax values were 56 and 166 U ml−1 for acid and alkaline proteases fromA. niger. However, Vmax for alkaline protease fromA. terreus was 29 U ml−1. The three proteases expressed the same value of Hill coefficient. Abscisic acid inhibited activities of the three proteases particularly those produced by A.terreus, a phenomenon that completely reversed with gibberellic acid (GA3), more permanently with acid protease fromA. niger. The purified protease was hardly affected with chelating agents and SH-reagents whereas inhibition was dependent on the nature of agent concentration and/or the source of enzyme. Proteases from the testedAspergillus strains exhibited promising hydrolytic activities towards fibrinogen, fibrin and blood clot. Thrombolytic activity varied among organisms and/or substrates.