Fullerol C60(OH)24 Nanoparticles Affect Secondary Metabolite Profile of Important Foodborne Mycotoxigenic Fungi In Vitro

The impact of fullerenol nanoparticles on the growth of toxigenic Aspergillus flavus and aflatoxins production in vitro and in corn flour

Antifungal and antimycotoxigenic activity of fullerenol nanoparticles (FNPs) were investigated on Aspergillus flavus growth isolated from a real food sample and aflatoxins (AFs) (AFB1 and AFB2 ) production. The final FNPs concentrations in in vitro and in commercial corn flour after the stationary incubation period of 7 and 14 days were in the range 0.16-80 µg/mL and 0.16-80 µg/g, respectively. Nanocharacterization of FNPs revealed an average size of 5-20 nm and a zeta potential of -35 mV. The highest degree of A. flavus mycelium growth inhibition (28%) after 7 days was observed for applied FNP concentration of 8.0 µg/mL, while after 14 days FNP concentration of 0.32 µg/mL led to the maximal inhibition of A. flavus mycelium growth (36%). Spearman's correlations analysis revealed a strong positive correlation between AFB1 and AFB2 concentrations in YES broth after 7 (R = 0.994, p < 0.05) and 14 days (R = 0.976), as well as between AFs concentrations and A. flavus mycelium mass after 7 (R = 0.786 for AFB1 and R = 0.766 for AFB2 ) and 14 days (R = 0.810 for AFB1 and R = 0.833 for AFB2 ). Paired samples t-test showed the existence of a statistically significant difference (p < 0.05) between the produced AFs concentrations after the incubation of 7 and 14 days. Regarding the artificially inoculated corn flour the lower applied FNP concentrations (0.16-0.8 µg/g) achieved a reduction of AFB1 up to 42% and 60% after 7 and 14 days, respectively.

Regulated Mycotoxin Occurrence and Co-Occurrence in Croatian Cereals

A total of 209 samples of various cereal crops (maize, wheat, barley, rye and oats) grown in Croatian fields during 2016 and 2017 were collected to analyze and determine the occurrence and co-occurrence of EU regulated mycotoxins in cereals (AFB1, AFB2, AFG1, AFG2, DON, FB1, FB2, ZEA, T-2, HT-2 and OTA). The analysis, performed by a validated confirmatory LC-MS/MS method based on a dilute and shoot principle, highlighted Fusarium mycotoxins as the main contaminants, often co-occurring in samples from both years (50.0% in 2016 and 33.7% in 2017). DON was found to be the most frequent mycotoxin, present in 72.5% of the 2016 samples and 32.6% of the 2017 samples, while maize proved to be the most contaminated cereal type of both years with FUM as the most abundant mycotoxins, with an average concentration of 1180 µg/kg. Moderate temperatures with periods of high humidity favored the accumulation of DON in wheat samples instead of other Fusarium mycotoxins, while similar conditions favored maize contamination with FUM. A total of 8.3% of all the 2016 harvest samples and 7.9% of the 2017 harvest samples were assessed as non-compliant, containing mycotoxins in concentrations higher than the levels set by the EU legislation for food.

Penicillium expansum Impact and Patulin Accumulation on Conventional and Traditional Apple Cultivars

Penicillium expansum is a necrotrophic plant pathogen among the most ubiquitous fungi disseminated worldwide. It causes blue mould rot in apples during storage, transport and sale, threatening human health by secreting patulin, a toxic secondary metabolite that contaminates apples and apple-derived products. Nevertheless, there is still a lack of sufficient data regarding the resistance of different apple cultivars to P. expansum, especially ancient ones, which showed to possess certain resistance to plant diseases. In this work, we investigated the polyphenol profile of 12 traditional and 8 conventional apple cultivar and their resistance to P. expansum CBS 325.48. Eight polyphenolic compounds were detected; the most prominent were catechin, epicatechin and gallic acid. The highest content of catechin was detected in ‘Apistar’—91.26 mg/100 g of fresh weight (FW), epicatechin in ‘Bobovac’—67.00 mg/100 g of FW, and gallic acid in ‘Bobovac’ and ‘Kraljevčica’—8.35 and 7.40 mg/100 g of FW, respectively. The highest content of patulin was detected in ‘Kraljevčica’ followed by ‘Apistar’—1687 and 1435 µg/kg, respectively. In apple cultivars ‘Brčko’, ‘Adamčica’ and ‘Idared’, patulin was not detected. Furthermore, the patulin content was positively correlated with gallic acid (r = 0.4226; p = 0.002), catechin (r = 0.3717; p = 0.008) and epicatechin (r = 0.3305; p = 0.019). This fact indicates that higher contents of gallic acid, catechin and epicatechin negatively affected and boost patulin concentration in examined apple cultivars. This can be related to the prooxidant activity of polyphenolic compounds and sensitivity of P. expansum to the disturbance of oxidative status.

Toxicity and action mechanisms of silver nanoparticles against the mycotoxin-producing fungus Fusarium graminearum

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AgNPs possess high activity towards fungicide-resistant strains.

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AgNPs exert great activity against mycotoxin-producing fungus F. graminearum.

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AgNPs induce the expression of two azole resistance-related ABC genes.

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AgNPs lead to accumulation of toxisome and notorious mycotoxin DON by provoking ROS.

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AgNPs combined with DON-reducing fungicides are recommended for FHB control.

Introduction

Fusarium graminearum is a most destructive fungal pathogen that causes Fusarium head blight (FHB) disease in cereal crops, resulting in severe yield loss and mycotoxin contamination in food and feed. Silver nanoparticles (AgNPs) are extensively applied in multiple fields due to their strong antimicrobial activity and are considered alternatives to fungicides. However, the antifungal mechanisms and the effects of AgNPs on mycotoxin production have not been well characterized.

Objectives

This study aimed to investigate the antifungal activity and mechanisms of AgNPs against both fungicide-resistant and fungicide-sensitive F. graminearum strains, determine their effects on mycotoxin deoxynivalenol (DON) production, and evaluate the potential of AgNPs for FHB management in the field.

Methods

Scanning electron microscopy (SEM), transmission electron microscopy (TEM), and fluorescence microscopy were used to examine the fungal morphological changes caused by AgNPs. In addition, RNA-Seq, qRT-PCR, and western blotting were conducted to detect gene transcription and DON levels.

Results

AgNPs with a diameter of 2 nm exhibited effective antifungal activity against both fungicide-sensitive and fungicide-resistant strains of F. graminearum. Further studies showed that AgNP application could impair the development, cell structure, cellular energy utilization, and metabolism pathways of this fungus. RNA-Seq analysis and sensitivity determination revealed that AgNP treatment significantly induced the expression of azole-related ATP-binding cassette (ABC) transporters without compromising the control efficacy of azoles in F. graminearum. AgNP treatment stimulated the generation of reactive oxygen species (ROS), subsequently induced transcription of DON biosynthesis genes, toxisome formation, and mycotoxin production.

Conclusion

This study revealed the underlying mechanisms of AgNPs against F. graminearum, determined their effects on DON production, and evaluated the potential of AgNPs for controlling fungicide-resistant F. graminearum strains. Together, our findings suggest that combinations of AgNPs with DON-reducing fungicides could be used for the management of FHB in the future.

Predicted Aflatoxin B1 Increase in Europe Due to Climate Change: Actions and Reactions at Global Level

Climate change (CC) is predicted to increase the risk of aflatoxin (AF) contamination in maize, as highlighted by a project supported by EFSA in 2009. We performed a comprehensive literature search using the Scopus search engine to extract peer-reviewed studies citing this study. A total of 224 papers were identified after step I filtering (187 + 37), while step II filtering identified 25 of these papers for quantitative analysis. The unselected papers (199) were categorized as “actions” because they provided a sounding board for the expected impact of CC on AFB₁ contamination, without adding new data on the topic. The remaining papers were considered as “reactions” of the scientific community because they went a step further in their data and ideas. Interesting statements taken from the “reactions” could be summarized with the following keywords: Chain and multi-actor approach, intersectoral and multidisciplinary, resilience, human and animal health, and global vision. In addition, fields meriting increased research efforts were summarized as the improvement of predictive modeling; extension to different crops and geographic areas; and the impact of CC on fungi and mycotoxin co-occurrence, both in crops and their value chains, up to consumers.

Fullerol C60(OH)24 Nanoparticles and Drought Impact on Wheat (Triticum aestivum L.) during Growth and Infection with Aspergillus flavus

Fullerol C₆₀(OH)₂₄ nanoparticles (FNP)-wheat-A. flavus interaction outcome is more complicated in the presence of drought. This study sheds light on how the presence of FNP affects food and feed safety from the perspective of mycotoxin contamination. The study aims to determine the influence of FNP at environmentally plausible concentrations on wheat growth under drought stress and on the aggressiveness of A. flavus during wheat germination, as well as the influence of FNP on the secondary metabolite profile during the inappropriate wheat storage. The co-occurrence of drought and FNP inhibited germination and shoot growth, while an application of FNP alone had no negative effect on plant growth. Wheat pre-treated with FNP showed a concentration dependent resistance pattern to A. flavus aggressiveness. Nevertheless, using a LC-MS/MS based multi-mycotoxin method, six secondary fungal metabolites: 3-nitropropionic acid (<LOD −775.7336 ± 10.7752 ng mL⁻¹), aflatoxin B1 (<LOD −6.78 ± 0.43 ng mL⁻¹) and B2 (<LOD −0.07 ± 0.00 ng mL⁻¹), aflatoxicol (<LOD −0.37 ± 0.16 ng mL⁻¹), kojic acid (<LOD −1337.87 ± 189.04 ng mL⁻¹), and O-methylsterigmatocystin (<LOD −0.17 ± 0.00 ng mL⁻¹), were detected. FNP affected secondary metabolism of A. flavus during inappropriate wheat storage and increased the concentration of secondary metabolites in a concentration-dependent pattern (3-nitropropionic acid and kojic acid). In addition, aflatoxicol production was provoked in FNP treated samples.

Mycotoxins, Pesticide Residues, and Heavy Metals Analysis of Croatian Cereals

Cereals are still one of the most important food and feed sources, thus determining cereal’s safety, i.e., compliance with legislation, is extremely important. As systematic investigations of nowadays unavoidable secondary fungal metabolites and other common legally regulated contaminants occurrence in Croatian cereals are still lacking, this research aims to monitor the contamination levels of nation-wide crops by mycotoxins, pesticide residues, and heavy metals by employing UHPLC-MS/MS, GC-MS/MS, and atomic absorption spectrometer (AAS) validated analytical methods. The most common secondary fungal metabolites were found to be Fusarium mycotoxins, with DON being the most occurring present in 73.7% of the samples. At least one pesticide residue was found in 331.8% of the samples, and Hg and Cd were the most occurring heavy metals. A total of 8.5% of the samples was non-compliant to the European Union (EU) legislation for food regarding the found mycotoxins concentrations, 4.5% regarding pesticide residues and none regarding heavy metals. The unusual presence of certain pesticide residue and heavy metal indicates the importance of systematic control of the contaminant presence, in order to gather enough occurrence data for proper risk assessment that these contaminants represent for the consumer’s health.