Advances in Food Mycology

Important Mycotoxins and the Fungi Which Produce Them 9
appear to be producers of OA, so this species may be of much less
importance than A. carbonarius in grapes, wine and green coffee beans
(Abarca et al., 1994; Taniwaki et al., 2003; Leong et al., 2004). It may
be of major importance, however, as A. niger NRRL 337, referred to
as the “food fungus”, produces large amounts of OA in pure culture.
This fungus is used for fermentation of potato peel waste etc. and used
for animal feed (Schuster et al., 2002).
Petromyces alliaceus (Lai et al., 1970), produces large amounts of
ochratoxin A in pure culture, and OA produced by this fungus has
been found in figs in California (Bayman et al., 2002). Aspergillus
steynii, from the Aspergillus section Circumdati, is also a very efficient
producer of OA, and has been found in green coffee beans, mouldy
soy beans and rice (Frisvad et al., 2004b). As with A. westerdijkiae,
A. steynii may have been identified as A. ochraceus earlier, so the relative
abundance of these three species is difficult to evaluate at present.
Penicillium verrucosum is the major producer of ochratoxin A in
stored cereals (Frisvad, 1985; Pitt, 1987; Lund and Frisvad, 2003).
Penicillium nordicum (Larsen et al., 2001) is the main OA producer
found in meat products such as salami and ham. Both OA producing
Penicillium species have been found on cheese also, but have only been
reported to be of high occurrence on Swiss hard cheeses (as P. casei,
Staub, 1911). The ex type culture of P. casei is a P. verrucosum (Larsen
et al., 2001).
Minor sources. Several Aspergilli can produce ochratoxin A in large
amounts, but they appear to be relatively rare. In Aspergillus section
Circumdati (formerly the Aspergillus ochraceus group), the following
species can produce ochratoxin A: Aspergillus cretensis, A. flocculosus,
A. pseudoelegans, A. roseoglobulosus, A. sclerotiorum, A. sulphureus and
Neopetromyces muricatus (Frisvad et al., 2004b). According to Ciegler
(1972) and Hesseltine et al. (1972) A. melleus, A. ostianus, A. persii and
A. petrakii may produce trace amounts of OA, but this has not been
confirmed since publication of those papers. Strains of these species
reported to produce large amounts of OA were reidentified by Frisvad
et al. (2004b). In Aspergillus section Flavi, Petromyces albertensis produces
ochratoxin A. In Aspergillus section Nigri, A. lacticoffeatus and
A. sclerotioniger produce ochratoxin A (Samson et al., 2004).
2.7. Sterigmatocystin
Sterigmatocystin is a possible carcinogen. However, its low solubility
in water or gastric juices limits its potential to cause human illness
(Pitt and Hocking, 1997).