Molecular variation analysis of Aspergillus flavus using polymerase chain reaction-restriction fragment length polymorphism of the internal transcribed spacer rDNA region.

Aspergillus flavus is the second most common disease-causing species of Aspergillus in humans. The fungus is frequently associated with life-threatening infections in immunocompromised hosts. The primary aim of the present study was to analyze the genetic variability among different isolates of A. flavus using polymerase chain reaction (PCR)-based restriction fragment length polymorphism (RFLP). A total of 62 A. flavus isolates were tested in the study. Molecular variability was searched for by analysis of the PCR amplification of the internal transcribed spacer (ITS) regions of ribosomal DNA using restriction enzymes. PCR using primers for ITS1 and ITS4 resulted in a product of ~600 bp. Amplicons were subjected to digestion with restriction endonucleases EcoRI, HaeIII and TaqI. Digestion of the PCR products using these restriction enzymes produced different patterns of fragments among the isolates, with different sizes and numbers of fragments, revealing genetic variability. In conclusion, ITS-RFLP is a useful molecular tool in screening for nucleotide polymorphisms among A. flavus isolates.