The genus Aspergillus (Anamorph) belongs to Deutromycets and has several species. Some of the species infected human, animal, plants and nuts.  Most of these species have ability to degrade plant components by production of pectinase enzyme. The species of Aspergillus flavus and Aspergillus niger are the most popular species of this genus. Although these species could be identified using morphological characters, the interspecific and intraspecific variation could not be evaluated.  Regarding pectic enzyme serection by the species, pectic zymogram technique was used as a simple and usefull method to identify the species and to detect inter and intraspecific variation. Initially the collected samples were transferred to the laboratory and after preparation were transferred on the appropriate media. The pure cultures were obtained for the sample with Aspergillus characteristics. Then Aspergillus fungi were identified microscopically based on morphological characters.  As a result, 40 isolates of A. niger and 30 isolates of A. flavus were recognized.  Then pured sampeles were transferred to liquid media contaning citrus pectin as a sole carbon source to induce the secretion of extracellular pectinase enzymes. After incubation for an optimised period the secreted pectinase enzymes was extracted and concentrated by Cephadex G150 and then loaded on the polyacrilamide horizontal gel and electerophoresed. There were 18 zymogram patterns for A. niger and 8 for A. flavus. The results based on the comparison of the zymogram patterns showed that there is inter and intraspecific variation for studied Aspergillus species.  It seems this technique could be used not only for the species identification, but also use to study of epidemiology of the fungs.

Chromium is one of the major causes of environmental pollution. To remove heavy metal ions from water, microorganisms can be used. In this study, dead fungal biomass of Aspergillus niger is used. The biomass was boiled in 0.5 N NaOH solutions to increase the metal removal capacity of A.niger and was applied when the pH of wash solution was in the normal range. The optimum adsorption pH value observed for chromium (VI) ions was 2. In these experiments, the influence of contact time, pH, Cr (VI) concentration, temperature, stirring speed, and different concentrations of biomass were evaluated.The results show that the experimental points fit both Freundlich and Langmuir models. Meanwhile, the curves of both of them were drawn. In Langmuir model, R2=0.9544 and in Freundlich model, R2=0.992. The Cr (VI) removal rate increases with the increase in temperature; that is, they are positively related. The removal rate of total chromium after 24 hours was %74.6. The results revealed that boiling biomass in NaOH had a better effect on biosorption of chromium so that adsorption would increase by many times. During the study, the amount of toxicity decreased as Cr (VI) was reduced to Cr (III). Part of Cr (VI) was also removed through surface adsorption.

Recently Aspergillus niger is the major source for gluconic acid and glucose oxidase production on large scale. Glucose oxidase may be used in industrial, agricultural and nutritional manner. It can be applied for the deletion of oxygen from the nutritional products, especially in conserves, in ligninolytic system for wood degredation, and for the fruits storage for a long time in refrigerator. From 17 wild and 2 standard strain of A.n. NRRL-3 was selected by nonspecific and specific colony staining method. Then the best strain in this step was cultured in liquid medium. The recent medium was contained glucose and calcium carbonate as main nutrients. In this medium it has been changed the concentration speed of shaking, temperature and pH. It has been concluded that the most important factor for glucose oxidase production is the concentration of glucose and calcium carbonate.After optimization other culture medium variables, finally NRRL-3 strain produced 2.2 IU/ml glucose oxidase in condition culture medium.

Kaolin is a clay mineral that has many industrial applications because of its special characteristics. One of the most important characteristic of this material is its whiteness and brightness. There are a lot of kaolin deposits in Iran that do not have appropriate brightness because of the presence of iron oxides in the ore. In this study, bioleaching of iron oxides by Aspergillus niger NCIM548 was applied to remove impurities from kaolin, and a model was presented to predict the extent of iron removal by this strain. Final results showed the removal of 2.2% of the total iron contents from kaolin that is promising for continuing studies in optimal conditions, and by using other strains of this fungus.

In this research different methods of DNA extraction from Aspergillus niger in tomato paste have been optimized and compared with each other. For this purpose classical optimization techniques and commercial Kit base methods were used. Mold spores of Aspergillus niger at different levels (101, 103 and 105 CFU/g) were added to the tomato paste. After mycelium growth DNA extraction was perfomed by five methods. Different methods employed by use the Liquid nitrogen, ultrasonic and lysis solution in the cell wall. These methods in terms of quality and quantity of DNA extracted were studied using spectrophotometer with NanoDrop. The absence of smear, protein contamination and no presecnce of PCR inhibitors determined with PCR that performed forward and reverse primers. Result of gel electrophoresis and PCR assay showed that Method 1 is the most appropriate method for DNA extraction is the mold of tomato paste.