| Popis: |
178 Penicillium strains were isolated from moulded feedstuffs (mainly corn and wheat after ambient air drying, wheat after refrigeration, corn after treatment with propionic acid), and investigated for the effect of temperature on growth rate. Temperatures between 4 and 27 degrees C were used. 159 strains proved psychrotrophic, they were able to grow at 4 degrees C on malt extract agar (MA) as well as in wheat; the growth in wheat was indicated by the production of ergosterol. On MA all psychrotrophic strains were able to grow also at 10-27 degrees C. The maximum rate of growth was reached at 10-15 degrees C, 15-20 degrees C, 20-27 degrees C, or must be assumed for temperatures greater than or equal to 27 degrees C. At 4 and 10 degrees C the mean growth rate on MA was 24 and 51%, respectively, related to the mean rate at 20 degrees C; the lower temperature limit of growth was found at - 1 degree C by graphic extrapolation. The Q10 value of growth on MA is about 2, if temperatures between 20 and 10 degrees C are compared; with decreasing temperature higher Q10 values up to 3.7 are obtained. The growth rate of a strain of Penicillium aurantiogriseum on wheat was affected by temperature nearly in the same manner as on malt extract agar. The results are discussed with respect to the risk of moulding during refrigerated storage of feedstuffs. |
