Patulin production by Penicillium granulatum and inhibition of ruminal flora.

The maximum patulin production by Penicillium granulatum was obtained during the 16th day of culture at 26 degrees C (2.9 g/L) on liquid Czapek medium (+ 8 p. 1000 glucose), followed by 32 degrees C after 24 days and 20 degrees C after 32 days. At 26 degrees C patulin production was maximum before the greatest rate of sporulation when the pH of the medium was about 4. Toxin production was studied by anaerobic culture for 75 days and then the cultures were exposed to ambient air. P. granulatum did not produce its toxin under anaerobic conditions. An in vitro fermentation model with rumen liquor was used, and within 4 hr acetic acid production declined and dose-dependent protein synthesis was inhibited with 20, 100, and 300 microgram patulin/mL rumen liquid.