The in vitro and in vivo production of pectic enzyme polygalacturonase (PG) by storage mold of rice Aspergillus niger and the effect of temperature and pH on the activity of the mold were investigated. The result of the assay for the production of polygalacturonase (PG) by the mold in vitro and in vivo showed that the activity of the enzyme when tested viscometrically, using 10% pectin was 142.9 R.V.U (Relative viscometric units) at 25 o C. The optimum activity of the enzyme secreted in vitro

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... Aspergillus niger was obtained at a temperature of 25 o C, and at temperature of 25 o C and 30 o C for that secreted in vivo., with a value of 142.9 R. V.U. The least activity of the enzyme was obtained at 20 o C, 40 o C, 45 o C and 50 o C in vitro, and at 20 o C ,45 o C and 50 o C with a value of 111.1 R.V.U each. The optimum activity of the enzyme produced in vitro by the fungus obtained at pH 5 and 6 with a value of 125R.V.U, and at pH 5 with a value of 142.9 R .V. U. in vivo. The activity of the enzyme was least at pH 2, 3, 4, 7,8, 9 and 10 in vitro, and at pH 2,3,8,9 and 10. in vivo with a value of 111.1 R. V. U. @JASEM