Seventy five fungal cultures were isolated from decayed citrus fruits and tested for their pectinolytic activity. Thirty six out of them proved to have ability for pectinase enzymes production. These isolates were identified and classified into twenty strains belonging to eleven species appertaining to six genera of fungi. Aspergillus was the first predominant genus followed by the genera of Cladosporium and Penicillium.
Evaluation of the twenty strains for their ability to produce pectinase enzymes indicated that the greatest clearing zones among the locally isolated fungi were observed with Aspergillus niger AUMC 4156 (22 mm) and Paecilomyces variotii AUMC 4149 (21 mm), which was mostly comparable with the pectinolytic activity of the imported strain Aspergillus niger NRRL 337 (23 mm). Studying the environmental and nutritional factors leading to maximum pectinase (s) production by these three strains showed that, the optimum incubation temperature and period for pectinase (s) production by Aspergillus niger NRRL 337, Aspergillus niger AUMC 4156 and Paecilomyces variotii AUMC 4149 were 30˚C and 5days, respectively.  The optimum pH values were 5 – 6, 5 and 6 for A. niger NRRL 337, A. niger AUMC 4156 and Paecilomyces variotii AUMC 4149, respectively.  The best inoculum size was 1% for Aspergillus niger NRRL 337, and 2% for both Aspergillus niger AUMC 4156 and Paecilomyces variotii AUMC 4149. Pectin at concentration of 2% proved to be the best carbon source followed by starch for all the studied fungal strains. Also, it was found that, the maximum enzyme production was attained by using of 2% yeast extract as the sole nitrogen source for all the studied fungi.