2.3. Study of pectinase activity of isolated pathogens Pectinase enzyme producing ability of seven different pathogenic isolates including the selected strain VBAM1, were evaluated with the method of Patil et al. (2010). The fungal strains were inoculated at the center of a pectin agar plate and incubated at 28 C for 72 h. After visual growth of the fungal mycelia, the plates were stained with 1% cetyl trimethyl ammonium bromide (CTAB). A zone of clearance indicated pectolytic activity. For evaluation of quantitative production of pectinase, samples of stock culture were added to 100 ml modified Czapek’s dox broth in 250 ml Erlenmeyer’s flasks containing pectin as the sole carbon source. The broth were incubated at 28 C up to 7 days. Aliquots were taken at 24 h intervals and were centrifuged at 10,000 rpm for 20 min.
1 ml of supernatant from each aliquots was taken and the amount of reducing sugar was measured using 3,5-dinitrosalicylic acid (DNSA) and OD was taken at 540 nm (Miller, 1959 ). The amountsof reducing sugar were calculated us ing standard curve of dextrose. Beside sugar estimation, the protein amounts in the culture medium were also measured by method of Lowry et al. (1951) at every 24 h interval.