Phenotypic and Genotyping Study of Aspergillus Niger: Molecular Detection of Calmodulin, 18srrna and Pepsin like Protease Genes Based on Multiplex PCR


Aspergillosis can be diagnosed using PCR. For this purpose, the genes encoding the 18S rRNA, Calmodulin and Pepsin-like protease genes of Aspergillus niger, were elucidated. Genus specific sequences could be identified in region of 18S rRNA. Methodology: 24 fungal strains were isolated from different localities of Al-Hillah city. Isolates were screened for glucose oxidase production using submerged fermentation and molecular techniques like 18S rRNA. DNA was isolated and amplified using PCR. Gene sequencing was done and homology analysis was studied. Rate of glucose oxidase production was also analyzed. Results: The method described in this study represents a rapid and reliable procedure to assess the presence in food products of two ochratoxigenic species of section Nigri. Glucose oxidase hyper producing isolate was identified as A. niger strain. The F17 strain gave best reproducible results (87. 5±0.05U/g of cell mass) after 72 h. of fermentation at 30ºC and at a medium pH of 7.2. The 18srDNA was used to detect A. niger was very affective. The identification and isolation of tannase gene from A. niger which is considered as an important bioreactor and industrial fungus were reported. Conclusion: Our results revealed that Glucose oxidase was produced naturally by A. niger in large quantity instead of using other manipulation techniques of genetic. The PCR technique we have used appears to be adequate to study a large group of microorganisms (fungi) and it help to identify risk of pathogenicity of aspergillosis.

Keywords: 18S rRNA, Aspergillosis, Aspergillus Niger, Calmodulin, Pepsin-Like Protease, Tannase.

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