Fungal protease: Production, purification and compatibility with laundry detergents and their wash performance

Abstract An extracellular serine protease producing fungi were isolated from the effluent sample collected from a sago industry in Salem and was identified as Graphium putredinis and Trichoderma harzianum . Intergenerically developed fusant produced high amounts of protease in soya bean meal amended minimal medium than the parents, G. putredinis and T. harzianum . The enzyme was purified by Sephadex G 100 column chromatography. The proteases of G. putredinis and T. harzianum had optimum pH and temperature of 7.0–8.0 and 50–60 °C respectively. At 37 and 60 °C, the parental proteases were respectively stable for 1 day and 15 min and the fusant was stable for 2 days and 10 min. The K m and V max were 0.65, 1.25 and 0.40 mg/ml and 2.00, 1.60 and 2.60 IU/mg protein for G. putredinis , T. harzianum and fusant respectively with a molecular weight of 31, 20 and 33 kDa. The effect of metal ions showed that, at 5 mM concentration of Hg 2+ , the residual protease activity of parent and fusant was 5.47, 2.48 and 9.76% respectively; Cu 2+ , Ca 2+ and Zn 2+ did not greatly affect the enzyme activity. In 5 mM EDTA showed residual activity between 60.76 and 85.66%. PMSF (2 mM) completely inhibited the protease activity of all the three fungi studied. All the three fungal enzymes retained maximum residual activity of 66.00, 63.80 and 76.74% with the commercial detergent Rin Advanced. With Kite, all the enzymes had more or less same level of residual activity (54–55%). With SDS and sodium perborate (0.2%) the residual activities were 58.25–73.82 and 61.58–70.24% respectively. Wash performance analysis revealed that fusant protease with Rin Advanced at 60 °C yielded good result.