Isolating,screening and identifying of polygalacturonase strain

One hundred and twenty strains,isolated from rotten fruits,soil,rice straw compost and biologic fertilizer,were screened for polygalacuronase production.All the strains were positive for pectinase activity in a translucent circle assay,as evidenced by clear translucent halos.Twenty strains presented considerable polygalacturonase activity.The cultivation of the best five strains(C1,C2,C3,G1,H4) by liquid-state fermentation,resulted in high activities of polygalacturonase enzyme.The enzyme activity were respectively 1 7.89,17.68,18.37,14.04,13.56 U/mL.Then they were classified respectively as Aspergillus terreus(C1,C2,C3),Alternaria alternate(G1),Aspergillus niger(H4) by the analysis of their colony morphology,micrology morphology,and physiology characteristic.