NEPHROTOXIC FUNGI IN FOODS FROM NEPHROPATHY HOUSEHOLDS IN BULGARIA

The Penicillium spp. and Aspergillus spp. associated with 83 samples of foods from Bulgarian households, most of which had a history of Balkan endemic nephropathy, have been defined. Penicillium aurantiogriseum was the most common species of this genus and all isolates tested were acutely nephrotoxic in the rat. P. verrucosum, a species normally associated with ochratoxin A biosynthesis in Europe, was rare and all isolates failed to elaborate ochratoxin A in pure culture. Several isolates of P. citrinum produced abundant citrinin when moulding moist shredded wheat, but such had no acute effect on rat kidneys. One apparently unique Penicillium isolate, best assigned to P. solitum, produced ochratoxin A in pure culture. Aspergilli of the flavus and glaucus groups were common, but A. ochraceus was relatively uncommon and no isolate produced more than a trace of ochratoxin A in pure culture. Beans, maize and other cereals generally contained no detectable ochratoxin A (< 1 mug kg-1). One apparently sound maize sample containing 153 mug ochratoxin A kg-1 did not contain A. ochraceus but two ochratoxinogenic fungi were isolated, which best conformed to P. viridicatum and P. griseofulvum. Seeds containing these fungi accounted for most of the ochratoxin A in the whole sample. The natural occurrence of ochratoxin A in food in the region is ascribed mainly to fungi which do not fit the current concept of ochratoxinogenic penicillia, but the low general natural incidence both of ochratoxinogenic fungi and also of ochratoxin A in the present study hardly supports the popular putative epidemiological role of ochratoxin A in the highly mosaic distribution of Balkan endemic nephropathy.