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

Single ascospore detection for the forecasting of Sclerotinia stem rot of canola

Smart-agriculture technologies comprise a set of management systems designed to sustainably increase the efficiency and productivity of farming. In this paper, we present a lab-on-a-chip device that can be employed as a plant disease forecasting tool for canola crop. Our device can be employed as a platform to forecast potential outbreaks of one of the most devastating diseases of canola and other crops, Sclerotinia stem rot. The system consists of a microfluidic chip capable of detecting single airborne Sclerotinia sclerotiorum ascospores. Target ascospores are injected into the chip and selectively captured by dielectrophoresis, while other spores in the sample are flushed away. Afterward, captured ascospores are released into the flow stream of the channel and are detected employing electrochemical impedance spectroscopy and coplanar microelectrodes. Our device provides a design for a low-cost, miniaturized, and automated platform technology for airborne spore detection and disease prevention.

Recent trends in detecting, controlling, and detoxifying of patulin mycotoxin using biotechnology methods

Patulin (PAT) is a mycotoxin that can contaminate many foods and especially fruits and fruit-based products. Therefore, accurate and effective testing is necessary to enable producers to comply with regulations and promote food safety. Traditional approaches involving the use of chemical compounds or physical treatments in food have provided practical methods that have been used to date. However, growing concerns about environmental and health problems associated with these approaches call for new alternatives. In contrast, recent advances in biotechnology have revolutionized the understanding of living organisms and brought more effective biological tools. This review, therefore, focuses on the study of biotechnology approaches for the detection, control, and mitigation of PAT in food. Future aspects of biotechnology development to overcome the food safety problem posed by PAT were also examined. We find that biotechnology advances offer novel, more effective, and environmental friendly approaches for the control and elimination of PAT in food compared to traditional methods. Biosensors represent the future of PAT detection and use biological tools such as aptamer, enzyme, and antibody. PAT prevention strategies include microbial biocontrol, the use of antifungal biomolecules, and the use of microorganisms in combination with antifungal molecules. PAT detoxification aims at the breakdown and removal of PAT in food by using enzymes, microorganisms, and various adsorbent biopolymers. Finally, biotechnology advances will be dependent on the understanding of fundamental biology of living organisms regarding PAT synthesis and resistance mechanisms.

Continuous separation of fungal spores in a microfluidic flow focusing device

The research of fungi is of great importance in a number of fields, such as environmental and healthcare studies. While there are a large number of optical and molecular methods available for characterization and identification of fungi and their spores, their isolation is still conducted using slow and labor-intensive methods. Here, we develop a microfluidic device for the continuous separation of fungal spores from other eukaryotic cells. The spores were separated through the microfluidic device by expanding pinched flow fractionation (PFF) containing the spores, achieving a spatial separation perpendicular to the flow direction according to the spore size. Further branch flow fractionation (BFF) and co-flow of a Newtonian and viscoelastic fluid were used to enhance the separation performance. Using this microfluidic device, we demonstrated the separation of two different types of fungal spores and further separation of fungal spores from eukaryotic cells with a separation efficiency of above 90%. Compared to the existing conventional methods, our microfluidic flow focusing device requires little manual handling and uses small amounts of samples without any pre-treatment steps of the samples.

Detection of Talaromyces macrosporus and Talaromyces trachyspermus by a PCR assay targeting the hydrophobin gene

Talaromyces species are typical fungi capable of producing the heat-resistant ascospores responsible for the spoilage of processed food products. Hydrophobins, which are unique to fungi, are small secreted proteins that form amphipathic layers on the outer surface of fungal cell walls. In this study, species-specific primer sets for detecting and identifying Talaromyces macrosporus and Talaromyces trachyspermus were designed based on hydrophobin gene sequences. A conventional polymerase chain reaction (PCR) assay using these primer sets produced species-specific amplicons for T. macrosporus and T. trachyspermus. The detection limit for each primer set was 100 pg template DNA. This assay also detected fungal DNA extracted from blueberries inoculated with T. macrosporus. Other heat-resistant fungi, including Byssochlamys, Neosartorya and Talaromyces species, which cause food spoilage, were not detected in PCR amplifications with these primer sets. Furthermore, a conventional PCR assay using a crude DNA extract as the template also yielded amplicons specific to T. macrosporus and T. trachyspermus. The simple and rapid PCR assay described herein is highly species-specific and can reliably detect T. macrosporus and T. trachyspermus, suggesting it may be relevant for the food and beverage industry. SIGNIFICANCE AND IMPACT OF THE STUDY: The heat-resistant ascospores of Talaromyces macrosporus and Talaromyces trachyspermus are responsible for food spoilage after pasteurization. Traditional methods for detecting fungal contamination based on morphological characteristics are time-consuming and exhibit low sensitivity and specificity. In this study, a conventional polymerase chain reaction (PCR) assay based on hydrophobin gene sequences was developed for the specific detection of T. macrosporus and T. trachyspermus. This detection method was simple, rapid and highly specific. These results suggest that the conventional PCR assay developed in this study may be useful for detecting T. macrosporus and T. trachyspermus in raw materials and processed food products.

Design of a species-specific PCR method for the detection of the heat-resistant fungi Talaromyces macrosporus and Talaromyces trachyspermus

Heat-resistant fungi occur sporadically and are a continuing problem for the food and beverage industry. The genus Talaromyces, as a typical fungus, is capable of producing the heat-resistant ascospores responsible for the spoilage of processed food products. Isocitrate lyase, a signature enzyme of the glyoxylate cycle, is required for the metabolism of non-fermentable carbon compounds, like acetate and ethanol. Here, species-specific primer sets for detection and identification of DNA derived from Talaromyces macrosporus and Talaromyces trachyspermus were designed based on the nucleotide sequences of their isocitrate lyase genes. Polymerase chain reaction (PCR) using a species-specific primer set amplified products specific to T. macrosporus and T. trachyspermus. Other fungal species, such as Byssochlamys fulva and Hamigera striata, which cause food spoilage, were not detected using the Talaromyces-specific primer sets. The detection limit for each species-specific primer set was determined as being 50 pg of template DNA, without using a nested PCR method. The specificity of each species-specific primer set was maintained in the presence of 1,000-fold amounts of genomic DNA from other fungi. The method also detected fungal DNA extracted from blueberry inoculated with T. macrosporus. This PCR method provides a quick, simple, powerful and reliable way to detect T. macrosporus and T. trachyspermus.

SIGNIFICANCE AND IMPACT OF THE STUDY

Polymerase chain reaction (PCR)-based detection is rapid, convenient and sensitive compared with traditional methods of detecting heat-resistant fungi. In this study, a PCR-based method was developed for the detection and identification of amplification products from Talaromyces macrosporus and Talaromyces trachyspermus using primer sets that target the isocitrate lyase gene. This method could be used for the on-site detection of T. macrosporus and T. trachyspermus in the near future, and will be helpful in the safety control of raw materials and in food and beverage production.

Development of Rapid Identification and Risk Analysis of Moniliella Spp. in Acidic Processed Foods

The number of spoilage incidents in the food industry attributable to a species of the genus Moniliella has recently increased, but the risk of food spoilage has not yet been evaluated. The purpose of this study was to develop a method to rapidly identify high-risk species and to conduct a risk analysis study of Moniliella spp. Acetic acid resistance of M. acetoabutens and ethanol resistance of M. suaveolens were higher than for other Moniliella species. All examined strains of M. acetoabutens developed a high tolerance to acetic acid by being cultured twice in liquid media containing low concentrations of acetic acid. These findings indicate that M. acetoabutens and M. suaveolens are high-risk species for food spoilage and must be discriminated from other fungi. We developed species-specific primers to identify M. acetoabutens and M. suaveolens using the polymerase chain reaction (PCR) to amplify the D1/D2 domain of 28S rDNA. The PCR using the primer sets designed for M. acetoabutens (Mac_F1/R1) and M. suaveolens (Msu_F1/R1) was specific to the target species and did not detect other fungi involved in food spoilage or environmental contamination. This method is expected to be effective for the monitoring of raw materials and components of the food production process.

Method for rapid detection and identification of chaetomium and evaluation of resistance to peracetic acid

In the beverage industry, peracetic acid has been increasingly used as a disinfectant for the filling machinery and environment due to merits of leaving no residue, it is safe for humans, and its antiseptic effect against fungi and endospores of bacteria. Recently, Chaetomium globosum and Chaetomium funicola were reported resistant to peracetic acid; however, little is known concerning the detail of peracetic acid resistance. Therefore, we assessed the peracetic acid resistance of the species of Chaetomium and related genera under identical conditions and made a thorough observation of the microstructure of their ascospores by transmission electron microscopy. The results of analyses revealed that C. globosum and C. funicola showed the high resistance to peracetic acid (a 1-D antiseptic effect after 900 s and 3-D antiseptic effect after 900 s) and had thick cell walls of ascospores that can impede the action mechanism of peracetic acid. We also developed specific primers to detect the C. globosum clade and identify C. funicola by using PCR to amplify the β-tubulin gene. PCR with the primer sets designed for C. globosum (Chae 4F/4R) and C. funicola (Cfu 2F/2R) amplified PCR products specific for the C. globosum clade and C. funicola, respectively. PCR with these two primer sets did not detect other fungi involved in food spoilage and environmental contamination. This detection and identification method is rapid and simple, with extremely high specificity.

Method for identifying heat-resistant fungi of the genus Neosartorya

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.