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.

Aspergillus flavus is a saprophytic fungus contaminating different food and nut products by aflatoxin which is a major problem worldwide. Modified atmosphere packaging (MAP) could be an effective method for control of saprophytic fungi and their toxins and secondary metabolites production. This study gives the consequences of fungal isolates growing under MAP condition on potato dextrose agar (PDA). Two isolates of A. flavus (A42 and CHAO50) were packed under 100% CO2, 100% O2 and vacuum conditions. The mycelial growth of fungal isolates on PDA was controlled up to 80% with CO2 treatment. Under the vacuum condition, mycelial growth of the isolates was inhibited up to 30%, while 100% oxygen had no inhibition on mycelial growth. Examination of isolates A42 and CHAO50 under UV light showed that both isolates produced yellow pigments on aflatoxin producing ability (APA) medium after 10 days. The levels of aflatoxin B1, B2, G1, G2 and total aflatoxin were analyzed chromatographically. The results revealed that the highest concentration of total aflatoxin was produced by fungal isolates grown in an atmosphere of 100% O2, while the level of aflatoxins was significantly reduced in 100% CO2.

Aspergillus parasiticus and Aspergillus flavus are the most important agents for contamination of food and are capable of production of carcinogenic toxins. Increasing awareness of optimal growth conditions helps to control and prevent the contamination and toxicity of these fungi. This experiment was conducted in order to study the effect of temperature, pH and seed moisture content on the growth of these fungi. The effect of corn seed moisture, at levels 15, 18, 21, 24, 27 and 30 percent on corn, and temperature, at level 18, 22, 25, 28, 31 and 34 ° C, in PDA medium and the effect of pH at level 3, 4, 5, 6 and 7 in PDB medium were investigated on the growth of these two fungi. The growth rate of fungi and dry weight of mycelium fungi in different treatments was evaluated in a completely randomized design in four repetitions. Statistical analysis was performed by using SAS 9. 1 software. Also, to determine the presence of toxins in fungi was used of coconut– agar medium. The results showed that the optimum growth conditions are for A. parasiticus at 31° C, pH= 5 and seed moisture content of 27% and for A. flavus at 28° C, pH=6 and seed moisture content of 27%. It was also found, both fungal have the ability to produce aflatoxin. According to the results of this research can be concluded that A. parasiticus and A. flavus have the better grow in tropical and subtropical regions and decrease moisture content, low temperatures and cool in stock can play an effective role in preventing the growth of these fungi and in reducing their toxin production consequently.

Fifteen non-aflatoxigenic strains of Aspergillus flavus, representing a wide range of geographic regions of Iran (six provinces including Fars, Ardebil, Guilan, Golestan, Kerman and Semnan) and vegetative compatibility groups (VCGs) were collected from corn (Zea mays L.), peanut (Arachis hypogaea L.) and pistachio (Pistachia vera L.) soils and kernels, and were screened for the presence of aflatoxin biosynthesis genes in relation to their capability to produce aflatoxins, targeting the regulatory genes afIR and aflJ, the structural genes aflT, pksA,ver-1, omtA, omtB, aflD, ordA, verA, norA, hypA, norB, cypA, sugar utilization gene glcA and flanking region gene C3 (5' end) by PCR method. This process resulted in grouping of A. flavus strains into twelve different amplification patterns (I-XII), characterized by 10-14 different DNA bands. Our results reveal that aflatoxin biosynthesis regulatory genes (aflR and aflJ) and the structural gene hypA are more important genes to detect non-aflatoxigenic strains of A. flavus. For non-aflatoxigenic strains of A. flavus, no relationship was observed between the deletion pattern and geographic origin and/or VCG; which may indicate that non-aflatoxigenic strains of A. flavus did not originate independently at each locality. It is concluded that the aflatoxin gene cluster variability existing in the non-aflatoxigenic popula- tions of A. flavus can be useful for understanding the toxicological risk as well as the selection of biocontrol agents.

Aflatoxin is one of the most hazardous mycotoxins injurious to both humans and animals. Aflatoxin contamination of crops is a serious economic loss inflicted upon agriculture, food and animal industry throughout the entire world. In nature, there are microorganisms able to alleviate aflatoxin contamination in crop products. In this work, the effects of four strains of Bacillus subtilis in reducing aflatoxin, induced by Aspregillus flavus, were investigated under in vitro conditions. The results indicated that strain BsP1 could completely inhibit the mycelial growth of A. flavus in PDB liquid medium. Strains BsP4, BsP5 and BsP38 caused a mass reduction of 58.88, 27.41 and 29.03% of fungal biomass, followed by 86.85, 21.80 and 26.16% reduction of aflatoxin B1 (AFB1), respectively. There also was a negative significant correlation observed between the decrease in fungal biomass and AFB1 production. Bioremediation studies revealed that the bacteria didn’t have the ability to remediate AFB1 after 3 days of incubation. However, the strain BsP1 could completely remediate AFB1 even after 5 days of incubation. Cell walls of these bacterial strains showed no sign of an ability for binding and removing of AFB1. The supernatant fluid of strain BsP1 was considerably able to degrade AFB1. The results finally suggest that the promising isolate of B. subtilis is of the potential to reduce aflatoxin in susceptible crops, possibly through antibiosis and degradation mechanisms.

Background: Aspergillus flavus and A. fumigatus are the leading causes of invasive and non-invasive aspergillosis. The occurrence of A. flavus is worldwide especially in tropical and subtropical regions. The vital importance of A. flavus has increased in the last years. Presently the emergence of resistance to antifungal agents among Aspergillus species is dramatically increasing. Therefore, in the present study, we evaluated the in vitro activity of five antifungal agents against A. flavus and A. fumigatus isolated from different sources.Methods: In total, 100 strains of A. flavus, which have been isolated from various specimens (nail, bronchoalveolar lavage, paranasal sinus) from suspected patients of aspergillosis patients. All strains were identified based on conventional methods and subsequently confirmed by DNA sequencing of the β-tubulin gene. The minimal inhibitory concentrations (MIC) of Amphotericin B, itraconazole, voriconazole, posaconazole and minimal effective concentrations (MEC) for caspofungin were determined using the broth micro dilution method in accordance with the guidelines of Clinical and Laboratory Standards Institute (CLSI) document M38-A2. Results: The resulting MIC90 s for A. flavus strains showed an increasing order, as follows: Caspofungin (0.031 mg/ml), posaconazole (0.25 mg/ml); voriconazole (0.5 mg/ml), itraconazole (1 mg/ml) and amphotericin B (4 mg/ml). Although MIC90 for A. fumigatus strains was different as follows: Caspofungin (0.016 mg/ml), posaconazole (0.125 mg/ml); voriconazole (0.5 mg/ml), itraconazole (0.5 mg/ml) and amphotericin B (2 mg/ml).Conclusion: The present study based on in vitro activity showed that posaconazole followed by caspofungin, voriconazole might have a potent activity, and it could be the best alternative for previous antifungal.