2012 Volume 29 Issue 4 Pages 208-214
Ochratoxin A (OTA) is one of the most important mycotoxins because of its nephrotoxicity and possible carcinogen in human and animals. OTA is produced by several species in the fungal genera Aspergillus and Penicillium, mainly A. carbonarius, A. ochraceus and P. verrucosum. However, recently the majority of toxigenic isolates identified as A. ochraceus in earlier studies were split as segregate species (A. westerdijkiae or A. steynii) from A. ochraceus.
In this paper, species identification of the food-borne isolates that were formerly reported as A. ochraceus in Japan was carried out on the basis of conventional and phylogenetical analyses. Among a total of 21 isolates examined, 18 isolates from green coffee beans and one isolate from spoiled soy bean were newly identified as A. westerdijkiae, while each one isolate from domestic moldy rice and from fish processed product were newly identified as A. steynii. Most of these isolates were found to be able to produce OTA on yeast extract-sucrose agar (YES) medium in the range of 82–1,400 μg/g. Hence, it is possible that the majority of toxigenic isolates that were reported as A. ochraceus in earlier Japanese studies were actually A. westerdijkiae or A. steynii.