Antibacterial effects of Aspergillus crude metabolite isolated from citrus on Staphylococcus aureus (ATCC 13813)

Discovering species of microorganisms that have antimicrobial effects opened a new window to fight against microorganisms. Aspergillus fungus is one of these microorganisms that is very effective in fighting against pathogenic microbes. All species of Aspergillus do not have appropriate and similar antimicrobial effects, and it is important to identify and isolate species with antimicrobial effects. In this research, moldy citrus fruits were sampled and Aspergillus was isolated and identified from them. 3 species of Aspergillus flavus, Aspergillus niger isolate 1 and Aspergillus niger isolate 2 were isolated. After that, the crude metabolites of these molds were prepared in the liquid culture medium of Sabro dextrose broth in Shikardar incubator. Finally, the effect of these metabolites on Staphylococcus aureus was done on this bacterium through disc diffusion by determining the diameter of the growth inhibition halo of each of these metabolites, and then MIC and MBC were calculated. The average MIC of Aspergillus flavus metabolite on Staphylococcus aureus was calculated to be 208.33 μl/ml and its average MBC on this bacterium was 416.66 μl/ml. The average MIC of Aspergillus niger metabolite on Staphylococcus aureus was calculated to be 166.66 μl/ml and its average MBC was determined to be 333.33 μl/ml. Around the disks with 150, 165 and 180 microliters of Aspergillus niger metabolite, the average diameter of growth inhibition halo was 8, 8 and 8.33 mm, respectively. The metabolite of each Aspergillus produces different effects in preventing the growth of Staphylococcus aureus.