Risk analysis and development of a rapid method for identifying four species of Byssochlamys

Species of the genus Byssochlamys, heat-resistant fungi, cause the spoilage and poisoning of heat-processed acidic foods due to the formation of heat-resistant ascospores and the biosynthesis of patulin. Here we evaluated the heat resistance and patulin production of four species of Byssochlamys. Byssochlamys fulva was significantly more heat-resistant than the other species, and Byssochlamys lagunculariae and Byssochlamys nivea synthesized patulin. This is the first report of patulin production by B. lagunculariae. These findings indicate that the four species pose different health risks in food. Thus, we concluded that a method to identify the species of Byssochlamys is necessary. Identification at the species level based on morphology alone is difficult. We developed species-specific primers to identify B. nivea, B. fulva, B. lagunculariae, and Byssochlamys zollerniae using polymerase chain reaction (PCR) to amplify the β-tubulin gene. PCR using the primer sets designed for B. nivea (B. nivea1F/1R) amplified PCR products specific for B. nivea. Similarly, PCR using the B.fulva1F/1R, B.lag1F/1R and B.zol3F/R primer sets produced PCR products specific for B. fulva, B. lagunculariae, and B. zollerniae, respectively. PCR using these four primer sets did not detect other fungi involved in food spoilage and environmental contamination. This identification method is rapid and simple with extremely high specificity.