PCR-based diagnosis and quantification of mycotoxin producing fungi

Addressing the Concern of Orange-Yellow Fungus Growth on Palm Kernel Cake: Safeguarding Dairy Cattle Diets for Mycotoxin-Producing Fungi

Palm kernel cake (PKC), a byproduct of palm oil extraction, serves an important role in Ecuador's animal feed industry. The emergence of yellow-orange fungal growth in PKC on some cattle farms in Ecuador sparked concerns within the cattle industry regarding a potential mycotoxin-producing fungus on this substrate. Due to the limited availability of analytical chemistry techniques in Ecuador for mycotoxin detection, we chose to isolate and identify the fungus to determine its association with mycotoxin-producing genera. Through molecular identification via ITS region sequencing, we identified the yellow-orange fungus as the yeast Candida ethanolica. Furthermore, we isolated two other fungi-the yeast Pichia kudriavzevii, and the fungus Geotrichum candidum. Molecular identification confirmed that all three species are not classified as mycotoxin-producing fungi but in contrast, the literature indicates that all three have demonstrated antifungal activity against Aspergillus and Penicillium species, genera associated with mycotoxin production. This suggests their potential use in biocontrol to counter the colonization of harmful fungi. We discuss preventive measures against the fungal invasion of PKC and emphasize the importance of promptly identifying fungi on this substrate. Rapid recognition of mycotoxin-producing and pathogenic genera holds the promise of mitigating cattle intoxication and the dissemination of mycotoxins throughout the food chain.

Sampling locations and processing methods shape fungi microbiome on the surface of edible and medicinal Arecae semen

Introduction

Arecae semen, which is derived from the dried ripe seed of Areca catechu L., has been commonly used as one of the major traditional Chinese medicines (TCMs). Three types of crude herbal preparations, namely, raw Arecae semen (AS), Arecae semen tostum (SAS), and Arecae semen carbonisata (FAS), are available for different clinical applications in TCMs. Although aflatoxin contamination in Arecae semen has been reported preliminarily, only a few studies have been conducted on fungal contamination.

Methods

In this study, the presence of fungi on the surface of three Arecae semen (AS, SAS, and FAS) that collected from four provinces were investigated using high-throughput sequencing and internal transcribed spacer 2.

Results

Results showed that the phyla Ascomycota (75.45%) and Basidiomycota (14.29%) and the genera Wallemia (7.56%), Botryosphaeria (6.91%), Davidiella (5.14%), and Symbiotaphrina (4.87%) were the dominant fungi, and they presented significant differences in four areas and three processed products (p < 0.05). The α-diversity and network complexity exhibited significant differences in the four sampling locations (p < 0.05), with higher in Yunnan (Chao 1, 213.45; Shannon, 4.61; average degree, 19.96) and Hainan (Chao 1, 198.27; Shannon, 4.21; average degree, 22.46) provinces. Significant differences were noted in the three processed samples; and SAS group had highest α-diversity (Chao 1, 167.80; Shannon, 4.54) and network complexity (average degree, 18.32).

Conclusions

In conclusion, the diversity and composition of microbiome on the surface of Arecae semen were shaped by sampling location and processing methods. This work provides details on the surface microbiome of Arecae semen samples and highlights the importance of roles of origin and processing methods in microbiomes, ensuring drug efficacy and food safety.

Comprehensive review on patulin and Alternaria toxins in fruit and derived products

Mycotoxins are toxic secondary metabolites produced by certain fungi, which can contaminate various food commodities, including fruits and their derived products. Patulin and Alternaria toxins are among the most commonly encountered mycotoxins in fruit and their derived products. In this review, the sources, toxicity, and regulations related to these mycotoxins, as well as their detection and mitigation strategies are widely discussed. Patulin is a mycotoxin produced mainly by the fungal genera Penicillium, Aspergillus, and Byssochlamys. Alternaria toxins, produced by fungi in the Alternaria genus, are another common group of mycotoxins found in fruits and fruit products. The most prevalent Alternaria toxins are alternariol (AOH) and alternariol monomethyl ether (AME). These mycotoxins are of concern due to their potential negative effects on human health. Ingesting fruits contaminated with these mycotoxins can cause acute and chronic health problems. Detection of patulin and Alternaria toxins in fruit and their derived products can be challenging due to their low concentrations and the complexity of the food matrices. Common analytical methods, good agricultural practices, and contamination monitoring of these mycotoxins are important for safe consumption of fruits and derived products. And Future research will continue to explore new methods for detecting and managing these mycotoxins, with the ultimate goal of ensuring the safety and quality of fruits and derived product supply.

Surface fungal diversity and several mycotoxin-related genes' expression profiles during the Lunar Palace 365 experiment

BACKGROUND

Chinese Lunar Palace 1 (LP1) is a ground-based bio-regenerative life support system (BLSS) test bed integrating highly efficient plant cultivation, animal protein production, urine nitrogen recycling, and bioconversion of solid waste. To date, there has been no molecular method-based detailed investigation of the fungal community and mycotoxin potential in BLSS habitats. To ensure safe BLSS design for actual space missions, we analyzed the LP1 surface mycobiome and mycotoxin potential during the Lunar Palace 365 project through internal transcribed spacer region 1 (ITS1) amplicon sequencing and quantitative polymerase chain reaction (qPCR) with primers specific for idh, ver1, nor1, tri5, and ITS1.

RESULTS

The LP1 system exhibited significant differences in fungal community diversity compared to other confined habitats, with higher fungal alpha diversity and different community structures. Significant differences existed in the surface fungal communities of the LP1 habitat due to the presence of different occupant groups. However, there was no significant difference between fungal communities in the plant cabin with various occupants. Source tracker analysis shows that most of the surface fungi in LP1 originated from plants. Regardless of differences in occupants or location, there were no significant differences in mycotoxin gene copy number.

CONCLUSIONS

Our study reveals that plants are the most crucial source of the surface fungal microbiome; however, occupant turnover can induce significant perturbations in the surface fungal community in a BLSS. Growing plants reduced fungal fluctuations, maintaining a healthy balance in the surface fungal microbiome and mycotoxin potential. Moreover, our study provides data important to (i) future risk considerations in crewed space missions with long-term residency, (ii) an optimized design and planning of a space mission that incorporates crew shifts and plant growth, and (iii) the expansion of our knowledge of indoor fungal communities with plant growth, which is essential to maintain safe working and living environments. Video Abstract.

The Presence of Mycotoxins in Human Amniotic Fluid

Mycotoxin exposure assessments through biomonitoring studies, based on the analysis of amniotic fluid, provides useful information about potential exposure of mothers and fetuses to ubiquitous toxic metabolites that are routinely found in food and the environment. In this study, amniotic fluid samples (n = 86) were collected via abdominal amniocentesis at 15-22 weeks of gestation from pregnant women with a high risk of chromosomal anomalies or genetic fetal defects detected during 1st trimester prenatal screening. These samples were analyzed for the presence of the most typical Aspergillus, Penicillium and Fusarium mycotoxins, with a focus on aflatoxins, ochratoxins and trichothecenes, using the LC-FLD/DAD method. The results showed that the toxin was present in over 75% of all the tested samples and in 73% of amniotic fluid samples from fetuses with genetic defects. The most frequently identified toxins were nivalenol (33.7%) ranging from Collapse

Key Words

• Aspergillus
• Fusarium
• amniotic fluids
• fetal defects
• genetic abnormalities
• mycotoxins

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MESH Headings

• Amniotic Fluid/chemistry
• Biological Monitoring
• Congenital Abnormalities
• Female
• Fetus
• Humans
• Mycotoxins/analysis
• Pregnancy
• Pregnancy Trimester, Second

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Affiliation(s)

Karolina Gromadzka Department of Chemistry, Poznań University of Life Sciences, ul. Wojska Polskiego 75, 60-625 Poznań, Poland
Jakub Pankiewicz Premedicare, NEW MED Medical Center, ul. Drużbickiego 13, 60-693 Poznań, Poland; (J.P.); (R.K.)
Monika Beszterda Department of Food Biochemistry and Analysis, Poznań University of Life Sciences, ul. Mazowiecka 48, 60-623 Poznań, Poland;
Magdalena Paczkowska The Institute of Mother and Child, ul. Kasprzaka 17a, 01-211 Warszawa, Poland; (M.P.); (B.N.)
Beata Nowakowska The Institute of Mother and Child, ul. Kasprzaka 17a, 01-211 Warszawa, Poland; (M.P.); (B.N.)
Rafał Kocyłowski Premedicare, NEW MED Medical Center, ul. Drużbickiego 13, 60-693 Poznań, Poland; (J.P.); (R.K.)

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In Vitro and In Vivo Evaluation of Silver Nanoparticles Phytosynthesized Using Raphanus sativus L. Waste Extracts

The aim of the current paper is the development of phytosynthesized silver nanoparticles mediated by Raphanus sativus L. extracts obtained through two extraction methods (temperature and microwave) and to test their potential application for controlling apple crops pathogens. The phytosynthesized materials were characterized by X-ray diffraction, scanning electron microscopy, and transmission electron microscopy. All the materials were evaluated in terms of antioxidant and in vitro antimicrobial activity (against bacteria, molds, and yeast: Escherichia coli ATCC 8738, Staphylococcus aureus ATTC 25923, Pseudomonas aeruginosa ATCC 9027, Salmonella typhimurium ATCC 14028, Candida albicans ATCC 10231, Venturia inaequalis, Podosphaera leucotricha, Fusarium oxysporum ATCC 48112, Penicillium hirsutum ATCC 52323, and Aspergillus niger ATCC 15475). Considering the results obtained in the in vitro assays, formulations based on nanoparticles phytosynthesized using Raphanus sativus L. waste extracts (RS1N) were evaluated as potential antifungal agents for horticultural crops protection, against Venturia inaequalis and Podosphaera leucotricha through in vivo assays. For the DPPH assay, the inhibition (%) varied between 37.06% (for RS1N at 0.8 mg/mL concentration) and 83.72% (for RS1N at 7.2 mg/mL concentration) compared to 19.97% (for RS2N at 0.8 mg/mL) and only 28.91% (for RS2N at 7.2 mg/mL). Similar results were obtained for RS3N (85.42% inhibition at 7.2 mg/mL) compared with RS4N (21.76% inhibition at 7.2 mg/mL). Regarding the ABTS assay, the highest scavenger activity values were recorded for samples RS1N (91.43% at 1.6 mg/mL) and RS3N (96.62% at 1.6 mg/mL).

A chemiluminescence-based heterogeneous asymmetric recombinase polymerase amplification assay for the molecular detection of mycotoxin producers

The analysis of mold in indoor air is a prominent topic but it is hardly dealt with. The most affected fields of this issue are residential- and occupational safety since mold can have a number of impacts on human health. To date the most used methods for quantification of microorganism contamination in indoor air are culture- or microscopy-based and are not capable of translating the on-site situation to analytical data reliably. Here we present a chemiluminescence-based method to detect mycotoxin producers through isothermal amplification of mycotoxin biosynthesis genes using glass and polycarbonate carriers. In this proof-of-principle study, zearalenone producers were aimed to be detected by heterogeneous asymmetric recombinase polymerase amplification (haRPA). For this, an appropriate lysis method for fungal spores was developed allowing rapid access to DNA. A system calibration with spores of Fusarium culmorum as zearalenone-producing organism resulted in an LOD of 2.7 × 10⁵ spores per ml. The system was shown to be specific for zearalenone producers. This work presents the first application of a heterogeneous isothermal amplification for rapid detection and quantification of mycotoxin producers. In the future, a multiplex detection can be possible by haRPA.

Application of monoclonal antibodies in quantifying fungal growth dynamics during aerobic spoilage of silage

Proliferation of filamentous fungi following ingress of oxygen to silage is an important cause of dry matter losses, resulting in significant waste. In addition, the production of mycotoxins by some filamentous fungi poses a risk to animal health through mycotoxicosis. Quantitative assessment of fungal growth in silage, through measurement of ergosterol content, colony-forming units or temperature increase is limiting in representing fungal growth dynamics during aerobic spoilage due to being deficient in either representing fungal biomass or being able to identify specific genera. Here, we conducted a controlled environment aerobic exposure experiment to test the efficacy of a monoclonal antibody-based enzyme-linked immunosorbent assay (ELISA) to detect the proliferation of fungal biomass in six silage samples. We compared this to temperature which has been traditionally deployed in such experiments and on-farm to detect aerobic deterioration. In addition, we quantified ergosterol, a second marker of fungal biomass. After 8 days post-aerobic exposure, the ergosterol and ELISA methods indicated an increase in fungal biomass in one of the samples with a temperature increase observed after 16 days. A comparison of the methods with Pearson's correlation coefficient showed a positive association between temperature and ergosterol and both markers of fungal biomass. This work indicates that the technology has potential to be used as an indicator of microbial degradation in preserved forage. Consequently, if it developed as an on-farm technique, this could inform forage management decisions made by farmers, with the goal of decreasing dry matter losses, improving resource and nutrient efficiency and reducing risks to animal health.

A loop-mediated isothermal amplification (LAMP) based assay for the rapid and sensitive group-specific detection of fumonisin producing Fusarium spp

Fumonisins are mycotoxins that contaminate maize and maize-based food products, and feed. They have been associated with nerve system disorders in horses, pulmonary edema in swine as well as neural tube defects and esophageal cancer in humans. The fum1 gene codes for a polyketide synthase involved in the biosynthesis of fumonisins. It is present in the genomes of all fumonisin producing Fusarium spp. Reliable detection of fum1 can provide an estimate of the toxicological potential of cultures and food sources. Therefore, a fum1 specific LAMP assay was developed and tested with purified DNA of 48 different species from the Fusarium fujikuroi species complex (FFSC). The fum1 gene was detected in 22 species among which F. fujikuroi, F. globosum, F. nygamai, F. proliferatum, F. subglutinans and F. verticillioides were the most prominent fumonisin producers. None out of 92 tested non-Fusarium species showed cross reactions with the new assay. The lowest limit of detection (LOD) was 5 pg of genomic DNA per reaction for F. fujikuroi, F. nygamai and F. verticillioides. Higher LODs were found for other LAMP positive species. Apart from pure genomic DNA, the LAMP assay detected fumonisin-producers when 10³ conidia/reaction were used as template after mechanical lysis. LAMP-results were well correlated with FB1 production. This is the first report on fumonisin production in strains of F. annanatum, F. coicis, F. mundagurra, F. newnesense, F. pininemorale, F. sororula, F. tjataeba, F. udum and F. werrikimbe. Usefulness of the LAMP assay was demonstrated by analyzing fumonisin contaminated maize grains. The new LAMP assay is rapid, sensitive and reliable for the diagnosis of typical fumonisin producers and can be a versatile tool in HACCP concepts that target the reduction of fumonisins in the food and feed chain.

Specific Detection and Identification of Fusarium graminearum Sensu Stricto Using a PCR-RFLP Tool and Specific Primers Targeting the Translational Elongation Factor 1α Gene

Fusarium graminearum is a toxigenic plant pathogen that causes Fusarium head blight (FHB) disease on cereal crops. It has recently shown to have cross-pathogenicity on noncereals (i.e., Fusarium root rot [FRR] on soybean) in Canada and elsewhere. Specific detection and differentiation of this potent toxigenic, trichothecene-producing pathogen among other closely related species is extremely important for disease control and mycotoxin monitoring. Here, we designed a PCR restriction fragment length polymorphism protocol based on the DNA sequence of the translational elongation factor 1α (TEF1α) gene. A unique restriction site to the enzyme HpaII is only found in F. graminearum sensu stricto strains among different Fusarium strains in the F. graminearum species complex (FGSC) and other Fusarium spp. associated with FHB in cereals and FRR in soybean. Partial amplification of the TEF1α gene with newly designed primers mh1/mh2 generated a 459-bp PCR fragment. Restriction digestion of the generated fragments with the HpaII enzyme generated a unique restriction pattern that can rapidly and accurately differentiate F. graminearum sensu stricto among all other Fusarium spp. A primer pair (FgssF/FgssR) specific to F. graminearum sensu stricto also was designed and can distinguish F. graminearum sensu stricto from all other Fusarium spp. in the FGSC and other closely related Fusarium spp. involved in FHB and FRR. This finding will be very useful for the specific detection of F. graminearum sensu stricto for diagnostic purposes as well as for the accurate detection of this pathogen in breeding and other research purposes.

Current PCR-based methods for the detection of mycotoxigenic fungi in complex food and feed matrices

Mycotoxins are toxic secondary fungal metabolites produced by certain types of filamentous fungi, such as Aspergillus, Fusarium, and Penicillium spp. Mycotoxigenic fungi and their produced mycotoxins are considered to be an important issue in food and feed safety due to their toxic effects like carcinogenicity, immunosuppression, neurotoxicity, nephrotoxicity, and hepatotoxicity on humans and animals. To boost the safety level of food and feedstuff, detection and identification of toxins are essential at critical control points across food and feed chains. Zero-tolerance policies by the European Union and other organizations about the extreme low level of tolerance of mycotoxins contamination in food and feed matrices have led to an increasing interest to design more sensitive, specific, rapid, cost-effective, and safer to use mycotoxigenic fungi detection technologies. Hence, many mycotoxigenic fungi detection technologies have been applied to measure and control toxins contamination in food and feed substrates. PCR-based mycotoxigenic fungi detection technologies, such as conventional PCR, real-time PCR, nested PCR, reverse transcriptase (RT)-PCR, loop-mediated isothermal amplification (LAMP), in situ PCR, polymerase chain reaction-denaturing gradient gel electrophoresis (PCR DGGE), co-operational PCR, multiplex PCR, DNA arrays, magnetic capture-hybridization (MCH)-PCR and restriction fragment length polymorphism (RFLP), would contribute to our understanding about different mycotoxigenic fungi detection approaches and will enhance our capability about mycotoxigenic fungi identification, isolation and characterization at critical control points across food and feed chains. We have assessed the principles, results, the limit of detection, and application of these PCR-based detection technologies to alleviate mycotoxins contamination problem in complex food and feed substrates. The potential application of these detection technologies can reduce mycotoxins in complex food and feed matrices.

Genome-wide Association Study and Genomic Prediction for Fusarium graminearum Resistance Traits in Nordic Oat (Avena sativa L.)

Fusarium head blight (FHB) and the accumulation of deoxynivalenol (DON) mycotoxin induced by Fusarium graminearum and other Fusarium fungi cause serious problems for oat production in the Nordic region (Scandinavia, Fennoscandia). Besides toxin accumulation, FHB causes reduction in grain yield and in germination capacity. Here, genomic approaches for accelerating breeding efforts against FHB and DON accumulation were studied. Resistance-related traits included DON content, F. graminearum DNA (relative to oat DNA) content (qFUSG) measured with real-time quantitative polymerase chain reaction (PCR), Fusarium-infected kernels (FIKs) and germination capacity (GC). Plant germplasm used in the study consisted of mostly breeding lines, and additionally, a few cultivars and exotic accessions. Genome-wide association study (GWAS) and genomic prediction, enabling genomic selection (GS) on the resistance-related and collected agronomic traits, were performed. Considerable genetic correlations between resistance-related traits were observed: DON content had a positive correlation (0.60) with qFUSG and a negative correlation (−0.63) with germination capacity. With the material in hand, we were not able to find any significant associations between markers and resistance-related traits. On the other hand, in genomic prediction, some resistance-related traits showed favorable accuracy in fivefold cross-validation (GC = 0.57). Genomic prediction is a promising method and genomic estimated breeding values (GEBVs) generated for germination capacity are applicable in oat breeding programs.

Polyphasic Assessment of Aflatoxin Production Potential in Selected Aspergilli

This study investigated the aflatoxin production potentials of selected fungi using a polyphasic approach. Internally transcribed spacer region of the fungi was amplified using the polymerase chain reaction. Forty-five Aspergillus strains were further assessed for aflatoxin production using the conventional methods such as growth on yeast extract sucrose, β-cyclodextrin neutral red desiccated coconut agar (β-CNRDCA); expression of the aflatoxin regulatory genes and the use of both thin-layer chromatography (TLC) and high-performance liquid chromatography (HPLC). A large proportion (82.22%) of the isolates harbored the Nor-1 gene while 55.56%, 68.89%, and 80% possessed the ver-1, omt-A, and aflR genes, respectively. All 100% the isolates harbored the aflJ gene. Twenty-three isolates were positive for aflatoxin production based on the yeast extract sucrose medium (YES) test; ammonium vapor test (51%), yellow pigment production (75.5%), and β-CNRDCA tests; and blue/green fluorescence (57.7%). Based on TLC detection 42.2% produced aflatoxins while in the HPLC, total aflatoxin (AFTOT) production concentrations ranged from 6.77-71,453 µg/g. Detectable aflatoxin B1 (AFB1) concentrations obtained from the HPLC ranged between 3.76 and 70,288 µg/g; 6.77 and 242.50 µg/g for aflatoxin B2 (AFB2); 1.87 and 745.30 µg/g for aflatoxin G1 (AFG1); and 1.67 and 768.52 µg/g for aflatoxin G2 (AFG2). AFTOT contamination levels were higher than European Union tolerable limits (4 µg/kg). The regression coefficient was one (R2 = 1) while significant differences exist in the aflatoxin concentrations of Aspergillus (p ≤ 0.05). This study reports the potentials of Aspergillus oryzae previously known as a non-aflatoxin producer to produce AFG1, AFG2, AFB1, and AFB2 toxins. Aspergillus species in feedlots of animals reared for food are capable of producing aflatoxins which could pose hazards to health.

Bioinformatics analysis of aflatoxins produced by Aspregillus sp. in basic consumer grain (corn and rice) in Saudi Arabia

The food contaminants by aflatoxins are inevitable even when all precautions and good agricultural practices are applied. Samples of white rice and corn (yellow, red) grains were collected from different local markets and houses. Three Aspergillus flavus strain isolated were identified using molecular characterization of AFLR (aflR) toxin gene. DNA genome of the three A. flavus isolates (namely A. flavus _ YC; A. flavus _ RC; A. flavus _ Rice) which corresponds to isolates from, yellow corn, red corn and white rice respectively were used as a template for PCR to amplify Aspergillus flavus AFLR (aflR) toxin gene. Partially sequenced was amplified using a specific primer set to confirm its identity, phylogenetic relationships between the three isolates as well as determination of the corresponding antigenic determinants. The epitope prediction analysis demonstrated that there were 1, 2, 3 and 4 epitopes whose score were equal 1 in A. flavus _ YC; A. flavus _ RC; A. flavus _ Rice, respectively. Interestingly, there were great dissimilarity in the epitope sequences among the three isolates except in RLQEGGDDAAGIPA, SPPPPVETQGLGGD, RPSESLPSARSEQG and PAHNTYSTPHAHTQ were found to be similar between all isolates. This work articulates that the molecular identification and characterization of three A. flavus using Aspergillus flavus AFLR (aflR) toxin gene and the unique antigenic determinants that could be used for design of a broad-spectrum antibody for rapid detection of A. flavus in foods and support quality system of food safety.

Improvement of the Culture Medium for the Dichlorvos-Ammonia (DV-AM) Method to Selectively Detect Aflatoxigenic Fungi in Soil

The dichlorvos-ammonia (DV-AM) method is a simple but sensitive visual method for detecting aflatoxigenic fungi. Here we sought to develop a selective medium that is appropriate for the growth of aflatoxigenic fungi among soil mycoflora. We examined the effects of different concentrations of carbon sources (sucrose and glucose) and detergents (deoxycholate (DOC), Triton X-100, and Tween 80) on microorganisms in soils, using agar medium supplemented with chloramphenicol. The results demonstrated that 5–10% sucrose concentrations and 0.1–0.15% DOC concentrations were appropriate for the selective detection of aflatoxigenic fungi in soil. We also identified the optimal constituents of the medium on which the normal rapid growth of Rhizopus sp. was completely inhibited. By using the new medium along with the DV-AM method, we succeeded in the isolation of aflatoxigenic fungi from non-agricultural fields in Fukui city, Japan. The fungi were identified as Aspergillus nomius based on their calmodulin gene sequences. These results indicate that the new medium will be useful in practice for the detection of aflatoxigenic fungi in soil samples including those from non-agricultural environments.

Analysis of the Fungal Community in Ziziphi Spinosae Semen through High-Throughput Sequencing

Ziziphi Spinosae Semen (ZSS) has been widely used in traditional Chinese medicine system for decades. Under proper humidity and temperature, ZSS is easily contaminated by fungi and mycotoxins during harvest, storage, and transport, thereby posing a considerable threat to consumer health. In this study, we first used the Illumina MiSeq PE250 platform and targeted the internal transcribed spacer 2 sequences to investigate the presence of fungi in moldy and normal ZSS samples collected from five producing areas in China. Results showed that all 14 samples tested were contaminated by fungi. Ascomycota was the dominant fungus at the phylum level, accounting for 64.36⁻99.74% of the fungal reads. At the genus level, Aspergillus, Candida, and Wallemia were the most predominant genera, with the relative abundances of 13.52⁻87.87%, 0.42⁻64.56%, and 0.06⁻34.31%, respectively. Meanwhile, 70 fungal taxa were identified at the species level. Among these taxa, three potential mycotoxin-producing fungi, namely, Aspergillusflavus, A. fumigatus, and Penicillium citrinum that account for 0.30⁻36.29%, 0.04⁻7.37%, and 0.01⁻0.80% of the fungal reads, respectively, were detected in all ZSS samples. Moreover, significant differences in fungal communities were observed in the moldy and normal ZSS samples. In conclusion, our results indicated that amplicon sequencing is feasible for the detection and analysis of the fungal community in the ZSS samples. This study used a new approach to survey the fungal contamination in herbal materials. This new approach can provide early warning for mycotoxin contamination in herbal materials, thereby ensuring drug efficacy and safety.

Achievements and Prospects in Electrochemical-Based Biosensing Platforms for Aflatoxin M₁ Detection in Milk and Dairy Products

Aflatoxins, which are mainly produced by Aspergillus flavus and parasiticus growing on plants and products stored under inappropriate conditions, represent the most studied group of mycotoxins. Contamination of human and animal milk with aflatoxin M₁, the hydroxylated metabolite of aflatoxin B₁, is an important health risk factor due to its carcinogenicity and mutagenicity. Due to the low concentration of this aflatoxin in milk and milk products, the analytical methods used for its quantification have to be highly sensitive, specific and simple. This paper presents an overview of the analytical methods, especially of the electrochemical immunosensors and aptasensors, used for determination of aflatoxin M₁.

Characterization of semen quality, testicular marker enzyme activities and gene expression changes in the blood testis barrier of Kunming mice following acute exposure to zearalenone

A total of 95 8-week-old male Kunming mice were randomly assigned into five groups and exposed to zearalenone (ZEA) at doses of 25, 50, and 75 mg/kg delivered by intra-peritoneal (i.p.) injection for 5 days. The testis and epididymis indices involving sperm quality and morphology, testis enzyme activities, serum concentrations of testosterone and estrogen, and the expression levels of the three gene and protein of N-cadherin, vimentin, and claudin 11 related to the blood testis barrier (BTB) were analyzed. Results showed that ZEA significantly decreased body weight and semen quality compared to the control group along with increased activity of alkaline phosphatase (ALP), acid phosphatase (ACP), lactate dehydrogenase (LDH), and reduced serum concentrations of testosterone and estrogen. At the mRNA and protein levels, expression of N-cadherin, vimentin, and claudin 11 significantly increased; however, the mRNA and protein of N-cad expression decreased. These data suggest acute exposure to ZEA reduces sperm quality and significantly decreases the concentration of serum testosterone and estradiol. In addition, the activities of the testis marker enzymes and associated mRNA and protein expressions of the BTB were also significantly affected. Our results demonstrated that ZEA has a significant impact on the reproductive parameters of male mice which showed compensatory response to strengthen the barrier function of the BTB following ZEA exposure.

The septins FaCdc3 and FaCdc12 are required for cytokinesis and affect asexual and sexual development, lipid metabolism and virulence in Fusarium asiaticum

Septins are a highly conserved family of GTP-binding proteins that contribute to many cellular and metabolic functions, including cell polarity, cytokinesis, cell morphogenesis and pathogenesis. In this study, we characterized the septins FaCdc3 and FaCdc12 in the filamentous fungus Fusarium asiaticum. The functions of FaCdc3 and FaCdc12 were evaluated by constructing deletion mutants of FaCdc3 and FaCdc12, designated ΔFaCdc3-5 and ΔFaCdc12-71, respectively. The deletion mutants exhibited a reduced rate of mycelial growth, increased aerial hyphae formation, irregularly shaped hyphae, reduced conidiation and a lack of sexual reproduction in wheat kernels. Histochemical analysis revealed that the conidia and hyphae of ΔFaCdc3-5 and ΔFaCdc12-71 formed large lipid droplets (LDs). ΔFaCdc3-5 and ΔFaCdc12-71 also exhibited increased resistance to agents that induce osmotic stress and damage the cell membrane and cell wall. In addition, the hyphae and conidia of the two mutants formed fewer septa than those of the wild-type and exhibited aberrant nuclear distribution. Pathogenicity assays showed that ΔFaCdc3-5 and ΔFaCdc12-71 exhibited reduced virulence on wheat spikelets, which was indirectly correlated with a reduced level of deoxynivalenol accumulation. All of these defects were restored by genetic complementation of the two mutants with the parental FaCdc3 and FaCdc12. These results indicate that FaCdc3 and FaCdc12 play a critical role in various cellular processes in F. asiaticum.

Targeting Other Mycotoxin Biosynthetic Genes

Real-time PCR (qPCR) methods are adequate tools for sensitive and rapid detection and quantification of toxigenic molds contaminating food commodities. Methods of qPCR for quantifying zearalenone (ZEA)-, sterigmatocystin (ST)-, cyclopiazonic acid (CPA)-, and patulin (PAT)-producing molds have been designed on the basis of specific target genes involved in the biosynthesis of these mycotoxins. In this chapter reliable qPCR protocols to detect and quantify such toxigenic molds are described. All of these methods are suitable when working with mold pure cultures and mold contaminated foods. For ZEA-producing molds, two qPCR using the SYBR Green fluorochrome and based on two polyketide synthase (PKS) genes are detailed. qPCR protocols relied on the fluG and the idh genes able to quantify ST- and PAT-producing molds, respectively, which can be performed by both SYBR Green and TaqMan methodologies are described. Regarding CPA-producing molds a TaqManq PCR method including a competitive internal amplification control is detailed. Since DNA extraction is a critical step in the detection and quantification of toxigenic molds by qPCR, a protocol for extracting DNA from mold pure cultures and food is also described.

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.

Aflatoxins and ochratoxin A and their Aspergillus causal species in Tunisian cereals

Occurrence of aflatoxins (AFs) AFB1, AFB2, AFG1, AFG2 and ochra toxin A (OTA) was studied in 65 samples of stored and freshly harvested wheat, barley and maize collected in Tunisia. The mycotoxins were simultaneously extracted and quantified by high performance liquid chromatography. Determination of AF-producing (section Flavi) and OTA-producing Aspergillus species (sections Nigri and Circumdati) was conducted in these samples by species-specific polymerase chain reaction (PCR). Results showed that most of maize samples were contaminated with AFs, data after storage showing lower values than those collected at harvest. All contaminated maize samples contained AFG1 and AFG2, among which 27.78% also had AFB1 and AFB2. This AFs pattern was consistent with the A. parasiticus toxin profile. A. flavus however showed the highest frequency in maize but was also found in barley and wheat where no AFs were detected. In contrast, OTA was neither found in maize nor in barley and only one wheat sample contained OTA. A. niger was the only OTA-producing species detected.

Myosins FaMyo2B and Famyo2 Affect Asexual and Sexual Development, Reduces Pathogenicity, and FaMyo2B Acts Jointly with the Myosin Passenger Protein FaSmy1 to Affect Resistance to Phenamacril in Fusarium asiaticum

We previously reported that mutations occurred in the gene myosin5 were responsible for resistance to the fungicide phenamacril in Fusarium graminearum. Here, we determined whether there is a functional link between phenamacril resistance and the myosin proteins FaMyo2B and Famyo2 in Fusarium asiaticum, which is the major causal agent of Fusarium head blight in China. We found that FaMyo2B acts jointly with FaSmy1 to affect resistance to phenamacril in F. asiaticum. We also found that FaMyo2B disruption mutant and Famyo2 deletion mutant were defective in hyphal branching, conidiation, and sexual reproduction. ΔFamyo2 also had an enhanced sensitivity to cell wall damaging agents and an abnormal distribution of septa and nuclei. In addition, the FaMyo2B and Famyo2 mutants had reduced pathogenicity on wheat coleoptiles and flowering wheat heads. Taken together, these results reveal that FaMyo2B and Famyo2 are required for several F. asiaticum developmental processes and activities, which help us better understand the resistance mechanism and find the most effective approach to control FHB.

Identification and Quantification of a Toxigenic and Non-Toxigenic Aspergillus flavus Strain in Contaminated Maize Using Quantitative Real-Time PCR

Aflatoxins, which are produced by Aspergillus flavus, are toxic to humans, livestock, and pets. The value of maize (Zea mays) grain is markedly reduced when contaminated with aflatoxin. Plant resistance and biological control using non-toxin producing strains are considered effective strategies for reducing aflatoxin accumulation in maize grain. Distinguishing between the toxin and non-toxin producing strains is important in determining the effectiveness of bio-control strategies and understanding inter-strain interactions. Using polymorphisms found in the fungal rRNA intergenic spacer region (IGS) between a toxigenic strain of A. flavus (NRRL 3357) and the non-toxigenic strain used in the biological control agent Afla-Guard(®) (NRRL 21882), we developed a set of primers that allows for the identification and quantification of the two strains using quantitative PCR. This primer set has been used to screen maize grain that was inoculated with the two strains individually and co-inoculated with both strains, and it has been shown to be effective in both the identification and quantification of both strains. Screening of co-inoculated ears from multiple resistant and susceptible genotypic crosses revealed no significant differences in fungal biomass accumulation of either strain in the field tests from 2010 and 2011 when compared across the means of all genotypes. Only one genotype/year combination showed significant differences in strain accumulation. Aflatoxin accumulation analysis showed that, as expected, genotypes inoculated with the toxigenic strain accumulated more aflatoxin than when co-inoculated with both strains or inoculated with only the non-toxigenic strain. Furthermore, accumulation of toxigenic fungal mass was significantly correlated with aflatoxin accumulation while non-toxigenic fungal accumulation was not. This primer set will allow researchers to better determine how the two fungal strains compete on the maize ear and investigate the interaction between different maize lines and these A. flavus strains.

Molecular strategies for detection and quantification of mycotoxin-producing Fusarium species: a review

Fusarium contamination is considered a major agricultural problem, which could not only significantly reduce yield and quality of agricultural products, but produce mycotoxins that are virulence factors responsible for many diseases of humans and farm animals. One strategy to identify toxigenic Fusarium species is the use of modern molecular methods, which include the analysis of DNA target regions for differentiation of the Fusarium species, particularly the mycotoxin-producing Fusarium species such as F. verticillioides and F. graminearum. Additionally, polymerase chain reaction assays are used to determine the genes involved in the biosynthesis of the toxins in order to facilitate a qualitative and quantitative detection of Fusarium-producing mycotoxins. Also, it is worth mentioning that some factors that modulate the biosynthesis of mycotoxins are not only determined by their biosynthetic gene clusters, but also by environmental conditions. Therefore, all of the aforementioned factors which may affect the molecular diagnosis of mycotoxins will be reviewed and discussed in this paper.

Expression Analysis of PKS13, FG08079.1 and PKS10 Genes in Fusarium graminearum and Fusarium culmorum

BACKGROUND

Identification and quantification of mycotoxins produced by Fusarium species are important in controlling fungal diseases.

OBJECTIVES

Potential of zearalenone, butenolide and fusarin C production was investigated in five Fusarium graminearum and five F. culmorum isolates at molecular level.

MATERIALS AND METHODS

Presence of PKS13, FG08079.1 and PKS10 genes, associated with production of zearalenone, butenolide and fusarin C, respectively, were confirmed by PCR. In addition, expression levels of them together with housekeeping gene (β-tubulin) were detected by real time PCR.

RESULTS

PKS13 and FG08079.1 transcripts were determined in all isolates, while PKS10 specific primers failed to amplify any product, indicative of no expression. ΔΔCTCT of PKS13 was ranged between 1.79E-03-3.97E-03 and for FG08079.1 was between 0.25E-03 and 6.02E-03. The highest PKS13 expressions were 3.86E-03 in F. graminearum F9 and 3.97E-03 in F. culmorum F16. Maximum FG08079.1 expressions were calculated as 6.02E-03 and 3.81E-03 in F. graminearum 2F and F. culmorum F2, respectively.

CONCLUSIONS

We revealed that ten Fusarium isolates produced zearalenone and butenolide under culture conditions. However, fusarin C was not generated by them in these conditions.

Disparate independent genetic events disrupt the secondary metabolism gene perA in certain symbiotic Epichloë species

Peramine is an insect-feeding deterrent produced by Epichloë species in symbiotic association with C3 grasses. The perA gene responsible for peramine synthesis encodes a two-module nonribosomal peptide synthetase. Alleles of perA are found in most Epichloë species; however, peramine is not produced by many perA-containing Epichloë isolates. The genetic basis of these peramine-negative chemotypes is often unknown. Using PCR and DNA sequencing, we analyzed the perA genes from 72 Epichloë isolates and identified causative mutations of perA null alleles. We found nonfunctional perA-ΔR* alleles, which contain a transposon-associated deletion of the perA region encoding the C-terminal reductase domain, are widespread within the Epichloë genus and represent a prevalent mutation found in nonhybrid species. Disparate phylogenies of adjacent A2 and T2 domains indicated that the deletion of the reductase domain (R*) likely occurred once and early in the evolution of the genus, and subsequently there have been several recombinations between those domains. A number of novel point, deletion, and insertion mutations responsible for abolishing peramine production in full-length perA alleles were also identified. The regions encoding the first and second adenylation domains (A1 and A2, respectively) were common sites for such mutations. Using this information, a method was developed to predict peramine chemotypes by combining PCR product size polymorphism analysis with sequencing of the perA adenylation domains.

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.

Mycotoxigenic moulds and mycotoxins in flours consumed in Turkey

BACKGROUND

Aflatoxins (AFs) and ochratoxin A (OTA) are metabolites produced by several fungi of the genera Aspergillus and Penicillium and have been found to contaminate human foods and animal feeds. The aim of this study was to investigate the abundance and diversity of total microfungi and mycotoxigenic fungi in 25 samples of different grain-based flours from four regions of Turkey (Thrace and Central, Northwest and West Anatolia) and to evaluate the level of AF and OTA contamination. Microscopic and polymerase chain reaction analyses were used to identify fungi, while high-performance liquid chromatography was used for the detection of AFs and OTA.

RESULTS

A total of 551 fungal strains were obtained from the samples and identified morphologically and by multi-locus gene sequencing. All samples were contaminated with fungi ((2-4.8) × 10(4) colony-forming units g(-1) ) and three of them exceeded the European Commission (EC) limits. The data also revealed that 70.5 and 14.7% of the fungal isolates were positive for AF and OTA production respectively. In addition, 21 samples were contaminated by AFs (14.98 and 22.4 µg kg(-1) for AFB1 ) and OTA (3.02 and 4.76 µg kg(-1) ) and three of them exceeded the EC limits.

CONCLUSION

This study is the first report on problems with the occurrence of microfungi, mycotoxin contamination, AFs and OTA in different grain-based flour samples from Turkey and highlights developable points of current limits for food and public health safety.

Specific detection of Bjerkandera adusta by polymerase chain reaction and its incidence in fungus-associated chronic cough

Chronic cough is a common symptom at outpatient care. An uncontrollable cough with difficulty in treatment is called chronic idiopathic cough. Recent reports have demonstrated that the presence of basidiomycetous fungi in sputum is an important clinical finding that assists in clarifying the cause of chronic cough in some cases. Research has suggested that Bjerkandera adusta is related to fungus-associated chronic cough (FACC). FACC is defined as a chronic cough associated with basidiomycetous fungi found in induced sputum and can be treated with antifungal medication. B. adusta is one of the basidiomycetous fungi that exist in cosmopolitan environments. The aim of this study was to develop a B. adusta detection method using polymerase chain reaction (PCR) with a specific primer set and to research the incidence of B. adusta in FACC. The new method successfully detected B. adusta from FACC patients. The incidence of B. adusta in FACC was 42.86 %. Antifungal drugs were effective in most cases. Significant differences in treatment duration between B. adusta patients and non-B. adusta patients were observed. It is therefore suggested that the presence of B. adusta may be one of the allergic intractable factors of chronic cough. This finding may provide identifiable differences in clinical manifestations between B. adusta and non-B. adusta in FACC and lead to possible differing remedies to treat the two forms. PCR can specifically detect B. adusta from patients suffering from chronic cough and provides a new diagnosis for FACC associated with B. adusta.

Antifungal efficacy of some natural phenolic compounds against significant pathogenic and toxinogenic filamentous fungi

In terms of food safety, species of the Fusarium, Aspergillus and Penicillium genera are considered the most significant because they produce the great majority of known mycotoxins. Developing resistance against commonly used fungicides have become a critical problem in area such as agriculture, the storage and production of food and even in human medicines. The need for research and development of new alternative antifungal treatment based on natural antifungal substances is obvious. Here, the antifungal efficacy of 21 phenolic components of essential oils and plant substances were tested against these filamentous fungi with respect to their different molecular structures. Minimum inhibitory concentration values MIC₅₀ and MIC₁₀₀ were successfully estimated for 15 substances by means of probit analysis. Thymol and carvacrol were evaluated as the most effective. The MIC₅₀ values for thymol ranged from 30 to 52 μg mL(-1). The MIC₁₀₀ values for thymol ranged from 76 to 255 μg mL(-1), respectively. For carvacrol, the MIC₅₀ values ranged from 37 to 76 μg mL(-1), and the MIC100 ranged from 131 to 262 μg mL(-1). The results also revealed differences in the efficacy of phenols depending on molecular structures and different inter-species sensitivity.

[Phosphate permease gene as a marker for the specific identification of toxigenic fungus Fusarium cerealis]

We have developed phosphate permease gene sequence-based PCR detection system of Fusarium cerealis phytopathogenic fungus. Sequencing and analysis revealed that the gene displayed unique polymorphism and could serve to establish phylogenetic relations as well as a marker to design specific primers. The specificity assay has confirmed the absence of cross reactions with DNAs of closely related Fusarium species. The qPCR assay demonstrated the 10 pg detection limit of specific DNA per reaction.

Propidium monoazide combined with real-time quantitative PCR to quantify viable Alternaria spp. contamination in tomato products

Alternaria is a common contaminating genus of fungi in fruits, grains, and vegetables that causes severe economic losses to farmers and the food industry. Furthermore, it is claimed that Alternaria spp. are able to produce phytotoxic metabolites, and mycotoxins that are unsafe for human and animal health. DNA amplification techniques are being increasingly applied to detect, identify, and quantify mycotoxigenic fungi in foodstuffs, but the inability of these methods to distinguish between viable and nonviable cells might lead to an overestimation of mycotoxin-producing living cells. A promising technique to overcome this problem is the pre-treatment of samples with nucleic acid intercalating dyes, such as propidium monoazide (PMA), prior to quantitative PCR (qPCR). PMA selectively penetrates cells with a damaged membrane inhibiting DNA amplification during qPCRs. In our study, a primer pair (Alt4-Alt5) to specifically amplify and quantify Alternaria spp. by qPCR was designed. Quantification data of qPCR achieved a detection limit of 10(2)conidia/g of tomato. Here, we have optimized for the first time a DNA amplification-based PMA sample pre-treatment protocol for detecting viable Alternaria spp. cells. Artificially inoculated tomato samples treated with 65μM of PMA, showed a reduction in the signal by almost 7cycles in qPCR between live and heat-killed Alternaria spp. conidia. The tomato matrix had a protective effect on the cells against PMA toxicity, reducing the efficiency to distinguish between viable and nonviable cells. The results reported here indicate that the PMA-qPCR method is a suitable tool for quantifying viable Alternaria cells, which could be useful for estimating potential risks of mycotoxin contamination.

Evaluation of a multiplex PCR assay for concurrent detection of four major mycotoxigenic fungi from foods

AIM

To develop and evaluate a multiplex polymerase chain reaction assay (mPCR) for the concurrent detection of four major mycotoxin metabolic pathway genes, viz. nor1 (aflatoxin), Tri6 (trichothecene), FUM13 (fumonisin) and otanps (ochratoxin A).

METHODS AND RESULTS

A mPCR assay with competitive internal amplification control, employing specific primers for each of the aforementioned four genes, was optimized and validated using 10 reference strains and 60 pure culture isolates. The standardized mPCR assay detected all four mycotoxin metabolic genes in artificially contaminated maize samples with a sensitivity of 2 × 10(3) CFU g(-1) for nor1-positive Aspergillus strains, Tri6 and FUM13-positive Fusarium strains and 2 × 10(4) CFU g(-1) for otanps-positive Penicillium strains. When the developed mPCR assay was applied to 40 natural foods, 35% (14 of 40) of the samples were contaminated with either one or more mycotoxins. The mPCR results were further evaluated with high-performance liquid chromatography (HPLC), and in general, both the methods provided unequivocal results.

CONCLUSION

The current mPCR assay is a rapid and reliable tool for simultaneous specific and sensitive detection of aflatoxigenic Aspergillus strains, trichothecene- and fumonisin-producing Fusarium strains, and ochratoxigenic Penicillium species from naturally contaminated foods.

SIGNIFICANCE AND IMPACT OF THE STUDY

This mPCR assay could be a supplementary strategy to current conventional mycotoxin analytical techniques such as thin-layer chromatography (TLC), high performance thin layer chromatography, HPLC, etc., and a reliable tool for high-throughput monitoring of major mycotoxin-producing fungi during the processing steps of food and feed commodities.

Integrated Use of Pyraclostrobin and Epoxiconazole for the Control of Fusarium Head Blight of Wheat in Anhui Province of China

Fusarium asiaticum and F. graminearum are the primary causal agents of Fusarium head blight (FHB) of wheat in China. Carbendazim (a benzimadazole fungicide, MBC), has been extensively used for the control of FHB, resulting in severe MBC resistance in China. This article presents the baseline sensitivity of F. asiaticum and F. graminearum isolates from Anhui Province of China to fungicides pyraclostrobin (a quinone outside inhibitor) and epoxiconazole (a sterol demethylation inhibitor). In the presence of salicylhydroxamic acid, the 50% effective concentration (EC₅₀) values for pyraclostrobin in inhibiting mycelial growth of the 126 F. asiaticum isolates and 63 F. graminearum isolates were 0.012 to 0.135 μg/ml and 0.010 to 0.105 μg/ml, and the EC₅₀ values for pyraclostrobin in inhibiting conidium germination of the F. asiaticum and F. graminearum populations were 0.047 to 0.291 and 0.042 to 0.255 μg/ml, respectively. The EC₅₀ values for epoxiconazole in inhibiting mycelial growth of the F. asiaticum and F. graminearum populations were 0.12 to 0.95 and 0.16 to 0.93 μg/ml, respectively. All of the baseline sensitivity curves were unimodal. This study also suggested that there was no cross-resistance between MBC and pyraclostrobin or epoxiconazole. In the protective and curative tests, pyraclostrobin and epoxiconazole applied at 200 and 300 μg/ml exhibited over 75% protective and curative control efficacy in all treatments. In field trials, both pyraclostrobin and epoxiconazole at 225 g a.i./ha provided over 80% efficacy in 2010 and 2011 at both sites where MBC resistance occurred, suggesting excellent activity against FHB. Interestingly, integrated use of pyraclostrobin + epoxiconazole applied at 150 + 150 g a.i./ha provided over 85% efficacy at both sites in 2010 and 2011. Pyraclostrobin and epoxiconazole should be good alternatives to MBC for the control of FHB, and integrated use of these two fungicides might achieve greater efficacy.

Hyd5 gene-based detection of the major gushing-inducing Fusarium spp. in a loop-mediated isothermal amplification (LAMP) assay

Fusarium graminearum and the closely related F. culmorum were found to be associated with over foaming of bottled beer (gushing) when contaminated brewing malt is used. The presence of highly surface active hydrophobins produced by these fungi upon growth on wheat or barley in the field or during malting may affect bubble formation and stability in gushing beers and other carbonated beverages. Aiming for a method for the rapid and user friendly analysis of unmalted and malted cereals during quality control in the brewing industry, a loop-mediated isothermal amplification (LAMP) assay for the detection of Fusarium spp. capable of producing the gushing inducing hydrophobin Hyd5p was set up. A set of primers was designed towards a 221 bp region within the hyd5 gene of F. culmorum. The LAMP product was verified by sequencing a 150 bp portion. Testing specificity with purified DNA from 99 different fungal species as well as barley and wheat showed that DNA synthesis only occurred during LAMP when DNA of the closely related species F. graminearum, F. culmorum, F. cerealis and F. lunulosporum were used as template. In-tube indirect detection of DNA amplification was applied using manganese-quenched calcein as fluorescence indicator for pyrophosphate produced during DNA synthesis. The assay had a detection limit of 0.74 pg of purified target DNA which corresponds 20 copy numbers per reaction within 30 minutes using a simple heating block. Analysis of Fusarium infected cereals revealed that the assay was able to detect F. graminearum at a level of 0.5% of infected grains in uninfected barley by analysis of surface washings without further sample preparation. Results show that the hyd5 based LAMP assay can be a rapid, useful and sensitive tool for quality control in the brewing and malting industry.

Use of the polymerase chain reaction for detection of Fusarium graminearum in bulgur wheat

The detection of mycotoxigenic fungi in foodstuff is important because their presence may indicate the possible associated mycotoxin contamination. Fusarium graminearum is a wheat pathogen and a producer of micotoxins. The polymerase chain reaction (PCR) has been employed for the specific identification of F. graminearum. However, this methodology has not been commonly used for detection of F. graminearum in food. Thus, the objective of the present study was to develop a molecular methodology to detect F. graminearum in commercial samples of bulgur wheat. Two methods were tested. In the first method, a sample of this cereal was contaminated with F. graminearum mycelia. The genomic DNA was extracted from this mixture and used in a F. graminearum specific PCR reaction. The F. graminearum species was detected only in samples that were heavily contaminated. In the second method, samples of bulgur wheat were inoculated on a solid medium, and isolates having F. graminearum culture characteristics were obtained. The DNA extracted from these isolates was tested in F. graminearum specific PCR reactions. An isolate obtained had its trichothecene genotype identified by PCR. The established methodology could be used in surveys of food contamination with F. graminearum.