Abstract: This study aimed to find out whether mold DNA can be amplified from traditional mold fermented foods and whether Aspergillus besides Monascus carries pksCT gene. The effect of thermal sterilization conditions on the degradation of the pksCT gene in red kojic rice wine was examined as well. Eleven samples of soy sauce, rice vinegar, fermented bean curd and yellow rice wine collected from local market were used for DNA extraction. Polymerase chain reaction (PCR) amplification was carried out with internal transcribed spacer (ITS) and pksCT gene primers. Rice wine was fermented by wheat koji and red koji, respectively, and then the pksCT gene was amplified and citrinin contents were measured before and during fermentation, after sterilization, and during storage. Samples were sterilized at 70, 80, 90, 100 ℃ for 10, 20, and 30 min, respectively, and then were subjected to PCR amplification. The results showed that DNA fragments were successfully amplified with the ITS primer from 4 samples, including soy sauce, rice vinegar, fermented bean curd and yellow rice wine. However, the pksCT gene was successfully amplified only from red bean curd fermented by Monascus. We failed to amplify the pksCT gene from yellow rice wine fermented by wheat koji. The pksCT gene was successfully amplified from red kojic rice wine during fermentation and after sterilization. Meanwhile, citrinin content increased rapidly at these sampling points. When red kojic rice wine was sterilized at 80 ℃ for 20 min or 90 ℃ for 10 min, the pksCT gene remained amplifiable, while after sterilization at 90 ℃ for 20 min or 100 ℃ for 10 min, DNA structure was damaged. The pksCT gene was amplifiable in Monascus fermented foods, but not in Aspergillus fermented foods. It is implied that mold DNA in fermented foods can be amplified by PCR and sequenced, which may be helpful for inspectors to find out what kinds of strains are contained in mold fermented foods, and provides a new terminal monitoring method for mold fermented foods.

Key words: mold, fermentation, pksCT gene, DNA, citrinin