Development of a PCR protocol to detect patulin producing moulds in food products

Talaromyces funiculosus, a Novel Causal Agent of Maize Ear Rot and Its Sensitivity to Fungicides

Ear rot is one of the most prevalent and destructive diseases of maize. During field surveys, it was found that a Penicillium ear rot broke out in some areas of Shanxi, Shaanxi, Hebei, and Tianjin in China, with an incidence of 3 to 90%. A Penicillium sp. was isolated from diseased kernels covered with greyish green mold, and three isolates were identified by morphologic and molecular characteristics. The pathogenicity of isolate ZBS205 to maize ears was further determined by artificial inoculation in a field. Furthermore, the sensitivity of isolate ZBS205 against six commonly used fungicides was also evaluated. According to macro- and micromorphologic characteristics, isolate ZBS205 was generally identical to Talaromyces funiculosus (teleomorph of Penicillium funiculosum). The partial gene sequences of the nuclear ribosomal ITS1-5.8S-ITS2 (ITS) region, β-tubulin, putative ribosome biogenesis protein (Tsr1), and the second largest subunit of the RNA polymerase II (RPB2) from isolates ZBS205, D49-1, and S73-1 showed the highest nucleotide identity to T. funiculosus strain X33, and the phylogenetic analysis conducted by the neighbor-joining method with the combined data of the four genes demonstrated that these three isolates clustered with T. funiculosus strain X33. These results suggested that the fungus isolated from diseased maize kernels was T. funiculosus. Pathogenicity testing showed that the T. funiculosus isolate ZBS205 was pathogenic to maize ears, which showed symptoms of rotted cob and deteriorated kernels. This is the first report of T. funiculosus as the definitive pathogen causing maize ear rot. The result of fungal sensitivity against fungicides showed that pyraclostrobin exhibited the highest toxicity to mycelial growth and could be used as a candidate agent for the prevention and control of T. funiculosus ear rot. The results of the present study provide a basis for understanding ear rot caused by T. funiculosus, and they should play an important role in disease management.

Aspergillus derived mycotoxins in food and the environment: Prevalence, detection, and toxicity

Aspergillus species are the paramount ubiquitous fungi that contaminate various food substrates and produce biochemicals known as mycotoxins. Aflatoxins (AFTs), ochratoxin A (OTA), patulin (PAT), citrinin (CIT), aflatrem (AT), secalonic acids (SA), cyclopiazonic acid (CPA), terrein (TR), sterigmatocystin (ST) and gliotoxin (GT), and other toxins produced by species of Aspergillus plays a major role in food and human health. Mycotoxins exhibited wide range of toxicity to the humans and animal models even at nanomolar (nM) concentration. Consumption of detrimental mycotoxins adulterated foodstuffs affects human and animal health even trace amounts. Bioaerosols consisting of spores and hyphal fragments are active elicitors of bronchial irritation and allergy, and challenging to the public health. Aspergillus is the furthermost predominant environmental contaminant unswervingly defile lives with a 40-90 % mortality risk in patients with conceded immunity. Genomics, proteomics, transcriptomics, and metabolomics approaches useful for mycotoxins' detection which are expensive. Antibody based detection of toxins chemotypes may result in cross-reactivity and uncertainty. Aptamers (APT) are single stranded DNA (ssDNA/RNA), are specifically binds to the target molecules can be generated by systematic evolution of ligands through exponential enrichment (SELEX). APT are fast, sensitive, simple, in-expensive, and field-deployable rapid point of care (POC) detection of toxins, and a better alternative to antibodies.

Aptasensors for mycotoxin detection: A review

Mycotoxins are toxic compounds produced by fungi, which represent a risk to the food and feed supply chain, having an impact on health and economies. A high percentage of feed samples have been reported to be contaminated with more than one type of mycotoxin. Systematic, cost-effective and simple tools for testing are critical to achieve a rapid and accurate screening of food and feed quality. In this review, we describe the various aptamers that have been selected against mycotoxins and their incorporation into optical and electrochemical aptasensors, outlining the strategies exploited, highlighting the advantages and disadvantages of each approach. The review also discusses the different materials used and the immobilization methods employed, with the aim of achieving the highest sensitivity and selectivity.

Patulin and Trichothecene: characteristics, occurrence, toxic effects and detection capabilities via clinical, analytical and nanostructured electrochemical sensing/biosensing assays in foodstuffs

Patulin and Trichothecene as the main groups of mycotoxins in significant quantities can cause health risks from allergic reactions to death on both humans and animals. Accordingly, rapid and highly sensitive determination of these toxics agents is of great importance. This review starts with a comprehensive outlook regarding the characteristics, occurrence and toxic effects of Patulin and Trichothecene. In the following, numerous clinical and analytical approaches have been extensively discussed. The main emphasis of this review is placed on the utilization of novel nanomaterial based electrochemical sensing/biosensing tools for highly sensitive determination of Patulin and Trichothecene. Furthermore, a detailed and comprehensive comparison has been performed between clinical, analytical and sensing methods. Subsequently, the nanomaterial based electrochemical sensing platforms have been approved as reliable tools for on-site analysis of Patulin and Trichothecene in food processing and manufacturing industries. Different nanomaterials in improving the performance of detecting assays were investigated and have various benefits toward clinical and analytical methods. This paper would address the limitations in the current developments as well as the future challenges involved in the successful construction of sensing approaches with the functionalized nanomaterials and also allow exploring into core-research works regarding this area.

Development and optimization of a loop-mediated isothermal amplification (LAMP) assay for the species-specific detection of Penicillium expansum

Penicillium expansum is the main cause of Blue Mold Decay, which is the economically most significant postharvest disease on fruits. It occurs especially on pomaceous fruits such as apples and pears but also on a wide range of other fruits such as grapes or strawberries. Besides its negative economic effects on the industry, the fungus is also of health concern as it produces patulin, a mycotoxin known to provoke harmful effects in humans. A specific and rapid detection of this fungus therefore is required. In the current study, a loop-mediated isothermal amplification (LAMP) assay was developed and optimized for the species-specific detection of P. expansum. The assay showed high specificity during tests with genomic DNA of 187 fungal strains. The detection limit of the developed assay was 25 pg genomic DNA of P. expansum per reaction. The assay was successfully applied for the detection of the fungus on artificially contaminated apples, grapes, apple juice, apple puree, and grape juice. The developed assay is a promising tool for rapid, sensitive, specific, and cost-efficient detection of P. expansum in quality control applications in the food and beverage industry.

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.

Isolation, Molecular Identification, and Mycotoxin Production of Aspergillus Species Isolated from the Rhizosphere of Sugarcane in the South of Iran

Knowledge of the genetic diversity detected among fungal species belonging to the genus Aspergillus is of key importance for explaining their important ecological role in the environment and agriculture. The current study aimed to identify Aspergillus species occurring in the rhizosphere of sugarcane in the South of Iran, and to investigate their mycotoxin profiles. One-hundred and twenty-five Aspergillus strains were isolated from the soil of eight major sugarcane-producing sites, and were molecularly identified using sequences of partial -tubulin (benA) and partial calmodulin (CaM) genes. Our molecular and phylogenetic results showed that around 70% of strains belonged to the Aspergillus section Nigri, and around 25% of species belonged to the Aspergillus section Terrei. Species belonging to both sections are able to produce different mycotoxins. The production of mycotoxins was measured for each species, according to their known mycotoxin profile: patulin (PAT) and sterigmatocystin (STG) for Aspergillusterreus; ochratoxin A (OTA) and fumonisins for Aspergilluswelwitschiae; and OTA alone for Aspergillustubingensis. The data showed that the production of OTA was detected in only 4 out of 10 strains of A.welwitschiae, while none of the A.tubingensis strains analyzed produced the mycotoxin. Fumonisins were produced by 8 out of 10 strains of A.welwitschiae. Finally, none of the 23 strains of A.terreus produced STG, while 13 of them produced PAT. The occurrence of such mycotoxigenic plant pathogens among the fungal community occurring in soil of sugarcane fields may represent a significant source of inoculum for the possible colonization of sugarcane plants, since the early stages of plant growth, due to the mycotoxin production capability, could have worrisome implications in terms of both the safety and loss of products at harvest.

Development and optimization of a group-specific loop-mediated isothermal amplification (LAMP) assay for the detection of patulin-producing Penicillium species

The mycotoxin patulin is a toxic fungal secondary metabolite occurring in food worldwide. Methods for rapid, simple and specific detection of patulin-producing fungi in food and feed are therefore urgently needed. In the current study, a loop-mediated isothermal amplification (LAMP) assay based on the isoepoxydon dehydrogenase (idh) gene of the patulin biosynthetic pathway was developed and optimized for the group-specific detection of patulin-producing Penicillium species. By testing purified DNA of 174 fungal strains representing 31 genera, the assay was demonstrated to be highly specific for the detection of patulin-producing species in Penicillium, Byssochlamys and Paecilomyces. The assay had a detection limit of 2.5 pg of purified genomic DNA of P. expansum per reaction. Moreover, the assay was demonstrated to detect patulin-producers when conidia were directly added to the master mix as template without any sample preparation. The applicability of the assay in food analyses was successfully tested on artificially contaminated grapes and apples requiring minimal sample preparation. A screening of grapes from the 2018 harvest from different locations in Germany revealed no presence of patulin-producers. The developed LAMP assay is a promising tool for rapid diagnosis in quality control applications in the food and beverage industry.

A critical review of producers of small lactone mycotoxins: patulin, penicillic acid and moniliformin

A very large number of filamentous fungi has been reported to produce the small lactone mycotoxins patulin, penicillic acid and moniliformin. Among the 167 reported fungal producers of patulin, only production by 29 species could be confirmed. Patulin is produced by 3 Aspergillus species, 3 Paecilomyces species, 22 Penicillium species from 7 sections of Penicillium, and one Xylaria species. Among 101 reported producers of penicillic acid, 48 species could produce this mycotoxin. Penicillic acid is produced by 23 species in section Aspergillus subgenus Circumdati section Circumdati, by Malbranchea aurantiaca and by 24 Penicillium species from 9 sections in Penicillium and one species that does not actually belong to Penicillium (P. megasporum). Among 40 reported producers of moniliformin, five species have been regarded as doubtful producers of this mycotoxin or are now regarded as taxonomic synonyms. Moniliformin is produced by 34 Fusarium species and one Penicillium species. All the accepted producers of patulin, penicillic acid and moniliformin were revised according to the new one fungus – one name nomenclatural system, and the most recently accepted taxonomy of the species.

Multiplex Detection of Toxigenic Penicillium Species

Multiplex PCR-based methods for simultaneous detection and quantification of different mycotoxin-producing Penicillia are useful tools to be used in food safety programs. These rapid and sensitive techniques allow taking corrective actions during food processing or storage for avoiding accumulation of mycotoxins in them. In this chapter, three multiplex PCR-based methods to detect at least patulin- and ochratoxin A-producing Penicillia are detailed. Two of them are different multiplex real-time PCR suitable for monitoring and quantifying toxigenic Penicillium using the nonspecific dye SYBR Green and specific hydrolysis probes (TaqMan). All of them successfully use the same target genes involved in the biosynthesis of such mycotoxins for designing primers and/or probes.

Screening and development of DNA aptamers as capture probes for colorimetric detection of patulin

Patulin (PAT) is a kind of mycotoxin that has serious harmful impacts on both food quality and human health. A high-affinity ssDNA aptamer that specifically binds to patulin was generated using systemic evolution of ligands by exponential enrichment (SELEX) assisted by graphene oxide (GO). After 15 rounds of positive and negative selection, a highly enriched ssDNA pool was sequenced and the representative sequences were subjected to binding assays to evaluate their affinity and specificity. Of the eight aptamer candidates tested, the sequence PAT-11 bound to patulin with high affinity and excellent selectivity with a dissociation constant (Kd) of 21.83 ± 5.022 nM. The selected aptamer, PAT-11, was subsequently used as a recognition element to develop a detection method for patulin based on an enzyme-chromogenic substrate system. The colorimetric aptasensor exhibited a linear range from 50 to 2500 pg mL(-1), and the limit of detection was found to be 48 pg mL(-1). The results indicated that GO-SELEX technology was appropriate for the screening of aptamers against small-molecule toxins, offering a promising application for aptamer-based biosensors.

Molecular characterization of patulin producing and non-producing Penicillium species in apples from Morocco

The isolation of patulin-producing Penicillia in apples collected in different markets in four localities in Morocco is reported. Fungi were identified by β-tubulin sequencing and further characterized using a specific PCR-based method targeting the isoepoxydon dehydrogenase (IDH) gene to discriminate between patulin-producing and non-producing strains. Production of patulin was also evaluated using standard cultural and biochemical methods. Results showed that 79.5% of contaminant fungi belonged to the genus Penicillium and that Penicillium expansum was the most isolated species (83.9%) followed by Penicillium chrysogenum (~9.7%) and Penicillium crustosum (~6.4%). Molecular analysis revealed that 64.5% of the Penicillium species produced the expected IDH-amplicon denoting patulin production in these strains. However, patulin production was not chemically confirmed in all P. expansum strains. The isolation of IDH(-)/patulin(+) strains poses the hypothesis that gentisylaldehyde is not a direct patulin precursor, supporting previous observations that highlighted the importance of the gentisyl alcohol in the production of this mycotoxin. Total agreement between IDH-gene detection and cultural/chemical methods employed was observed in 58% of P. expansum strains and for 100% of the other species isolated. Overall the data reported here showed a substantial genetic variability within P. expansum population from Morocco.

Development of a real-time PCR assay for Penicillium expansum quantification and patulin estimation in apples

Due to the occurrence and spread of the fungal contaminants in food and the difficulties to remove their resulting mycotoxins, rapid and accurate methods are needed for early detection of these mycotoxigenic fungi. The polymerase chain reaction and the real time PCR have been widely used for this purpose. Apples are suitable substrates for fungal colonization mostly caused by Penicillium expansum, which produces the mycotoxin patulin during fruit infection. This study describes the development of a real-time PCR assay incorporating an internal amplification control (IAC) to specifically detect and quantify P. expansum. A specific primer pair was designed from the patF gene, involved in patulin biosynthesis. The selected primer set showed a high specificity for P. expansum and was successfully employed in a standardized real-time PCR for the direct quantification of this fungus in apples. Using the developed system, twenty eight apples were analyzed for their DNA content. Apples were also analyzed for patulin content by HPLC. Interestingly, a positive correlation (R(2) = 0.701) was found between P. expansum DNA content and patulin concentration. This work offers an alternative to conventional methods of patulin quantification and mycological detection of P. expansum and could be very useful for the screening of patulin in fruits through the application of industrial quality control.