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Published on: September 28, 2021
Method for identifying heat-resistant fungi of the genus Neosartorya
Takashi Yaguchi1, Yumi Imanishi, Tetsuhiro Matsuzawa
1Medical Mycology Research Center, Chiba University, 1-8-1 Inohana, Chuo-ku, Chiba 260-8673, Japan. t-yaguchi@faculty.chiba-u.jp
Abstract:
Species of the genus Neosartorya are heat-resistant fungi that cause the spoilage of heat-processed acidic foods due to the formation of heat-resistant ascospores, and they produce mycotoxins, such as fumitremorgins and gliotoxin. Their anamorphs are phylogenetically and morphologically very close to Aspergillus fumigatus, which has never been reported as a spoilage agent in heat-processed food products. Therefore it is important to discriminate between the species of Neosartorya and A. fumigatus in the food industry. In the present study, we examined β-tubulin and calmodulin genes to identify Neosartorya and A. fumigatus at the species level and found a region for specifically detecting these species. We succeeded in developing the PCR method of differentiating and identifying Neosartorya and A. fumigatus using specific primer sets. Moreover, we developed specific primer sets to identify Neosartorya species, N. fischeri, N. glabra, N. hiratsukae, N. pseudofischeri, and N. spinosa-complex, which are important in food spoilage; these fungi vary in heat resistance and productivity of mycotoxins, depending on the species. PCR using these primer sets did not detect other fungi involved in food spoilage and environmental contamination. These identification methods are rapid and simple with extremely high specificity.
Insights
New PCR methods accurately identify heat-resistant fungi like Neosartorya species and Aspergillus fumigatus. This helps prevent spoilage in heat-processed foods by distinguishing these important foodborne fungi.
Area of Science:
- Food Microbiology
- Molecular Biology
- Mycology
Background:
- Neosartorya species are heat-resistant fungi causing spoilage in acidic foods via heat-resistant ascospores.
- These fungi produce mycotoxins (e.g., fumitremorgins, gliotoxin) and are morphologically similar to Aspergillus fumigatus.
- Distinguishing Neosartorya from A. fumigatus is crucial for the food industry due to differing spoilage potential.
Purpose of the Study:
- To develop rapid and specific molecular methods for identifying Neosartorya and A. fumigatus.
- To differentiate key Neosartorya species significant in food spoilage.
- To ensure accurate detection in food safety and quality control.
Main Methods:
- Analysis of beta-tubulin and calmodulin genes for species-specific detection.
- Development of Polymerase Chain Reaction (PCR) assays with specific primer sets.
- Testing primer sets against various food spoilage fungi and environmental contaminants.
Main Results:
- Successfully developed PCR methods to differentiate and identify Neosartorya and A. fumigatus.
- Created specific primer sets for identifying Neosartorya species (N. fischeri, N. glabra, N. hiratsukae, N. pseudofischeri, N. spinosa-complex).
- Validated methods showed high specificity, detecting only target species and no other fungi.
Conclusions:
- The developed PCR techniques offer rapid, simple, and highly specific identification of Neosartorya and A. fumigatus.
- These methods are valuable tools for the food industry in monitoring and controlling fungal contamination.
- Accurate identification aids in managing food spoilage and mycotoxin risks associated with these fungi.
