Project description:Penicillium citrinum X9-4, which was isolated from infected grapes by our laboratory, produced the highest amount of OTA at pH 5 in culture media, and toxin-production was restrained under acidic environment (pH 3). It revealed the possible mechanism of OTA biosynthesis and metabolic regulation in P. citrinum by transcriptomics, and investigated the reason of OTA biosynthesis was restrained in P. citrinum when cultured under acidic environment.