Fungal biota, with special reference to the genus Penicillium, was studied in 52 samples of commercial cheeses (10 fresh, I 7 semiripened and 25 ripened) made from different types of milk (cow, ewe, goat and mixed) produced in southern Spain. In 41 of the total of cheeses analyzed (79%) moldrr were isolated. Penicillium was identified in 63% of the samples, Mucor spp. in 27%, Geotrichum candidum in 17% and Cladosporium herbarum in 10%; eleven otherfingal genera were detected rangingfrom 2 to 4%. Thirty-five species of Penicillium were analyzed with the following distribution: 7 in fresh cheese, 16 in semiripened cheese and 30 in ripened cheese. The incidence of Penicillium spp. was also greater in the cheeses with a higher degree of ripeness, i.e. 20% in fresh cheese, 71% in the semiripened and 76% in the ripened cheese.

Contamination by fungi of the genus Aspergillus with special reference to the possible detection of aflatoxin-producing strains of Aspergillus flavus was studied in 52 samples of commercial cheeses made with different types of milk (8 of cow's milk, 12 of ewe's milk, 13 of goat's milk, and 19 of milk mixtures of various species: cow, ewe, and goat) produced in Southern Spain. The frequency of appearance of various species of Aspergillus, A. glaucus, A. niger, A. nidulans, A. sulphureus, A. Terreus, and A. flavus, in the different types of cheese was determined. In 4 (2 of goat's milk cheese and 2 of cheeses made with milk from various species) out of 52 samples (7.69%), aflatoxin-producing strains of A. flavus were detected.

Thirty-five samples of commercial cheeses, 9 fresh, 9 semicured or semiripened and 17 ripened made with different types of milk (cow, ewe, goat and mixtures of milk of various species) produced in the South of Spain were analyzed for the presence of aflatoxin M1 (AFM1) by high-performance liquid chromatography, In 16 of the 35 samples (45.71%) the presence of AFM1 was detected in concentrations ranging between 20 and 200 ng/g of cheese, In the positive cases, the mean levels of AFM1 were 105.33 ng/g in ripened cheeses, 73.80 ng/g in semiripened cheeses and 42.60 ng/g in fresh cheeses.