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.