Ochratoxin A in profiling and speciation

More than 20 species have been cited as ochratoxin A-producing fungi in the genus Aspergillus. However, few of them are known to be regularly the source of ochratoxin A (OTA) contamination of foods. OTA contamination of food was until recently believed to be produced only by Aspergillus ochraceus and by Penicillium verrucosum, which affect mainly dried stored foods and cereals respectively, in different regions of the world. Different methods have been developed to detect OTA producing fungi. Traditional mycological methods are time consuming and require taxonomical and chromatography expertise. Different molecular diagnostic methods for an early detection of ochratoxigenic fungi, using mainly PCR techniques, have also been proposed. However, OTA production is also included as a character for taxonomical purposes in classification and also for identification. As is well known in taxonomy, one difficulty in devising identification schemes is that the results of characterisation tests may vary depending on different conditions. We can find some confusing or controversial data about the ability to produce OTA by some species. Some examples found in the literature about these issues are discussed. © Wageningen Academic Publishers, The Netherlands, 2008.