Abstract
Confusion in defining the species producing OTA arose when P. viricatum was included to the toxigenic species by Walbeek et al. (1969) and then later by Ciegler et al. (1973). Pitt (1979, 1987) and Frisvad (1983,1986) determined only P. verrucosum was the OTA-producing species in Penicillium because P. viricatum and P. verrucosum were separated based on growth rate and profile of mycotoxin production profile. Recently, P. verrucosum from cheese and meats has been proposed as a new species P. nordicum because almost all P. verrucosum is derived from plants. P. verrucosum grows in the range of 0-31 °C with an optimum at 20 °C OTA production correlated well with the temperature range of growth being greater at optimum temperature. The minimum aw for growth and mycotoxin production is 0.86. Growth and the mycotoxin production are affected by the nature of substrates and the isolate. Cycling of temperature gradient causes moving of moisture in the grains stored in warehouse and allows fungal growth and the mycotoxin production when moisture content increase. Processing facilities for drying and storage of crops or foods should be cleaned to reduce the contamination potential because soil, residual grains, or old product may be the source of the P. verrucosum infection.
