Molecular detection of ochratoxigenic Aspergillus species isolated from coffee beans in Saudi Arabia.

Ten fungal isolates from coffee beans were morphologically identified as Aspergillus niger, A. ochraceus and A. carbonari-us (N = 5, 3, and 2, respectively). Only one isolate, morphologically identified as A. niger, was unable to produce ochratoxin A (OTA). This may be a new species in the Aspergillus section Nigri. OTA levels in all the other isolates were above the limit of detection (0.15 mg/kg). Based on microsatellite-primed PCR (MP-PCR) profiles, using three microsatellite primers, three main groups were obtained by UPGMA cluster analysis: A. niger, A. ochraceus and A. carbonarius. A clear-cut association was found between the MP-PCR genotype and the ability to produce OTA. Using the primer pairs OCRA1/OCRA2, a single fragment of about 400 bp was amplified only when genomic DNA from the A. ochraceus isolates was used.