Search Results (44)

Ochratoxin A (OTA) accumulation by Penicillium nordicum is enhanced at high salt concentrations. The genes involved in OTA biosynthesis include a polyketide synthase (PKS), although other PKSs outside the cluster could influence OTA production. This study aimed to evaluate a potential new PKS involved in OTA biosynthesis and the metabolites related to this mycotoxin. Optimised protocols were designed for the gene expression analysis of five genes that encoded the previously reported PKS to be overexpressed in dry-cured meat products (n2, n3, n4, n5 and n6). Their expression was tested in two P. nordicum strains (Pn15 and Pn856) grown in CYA medium with different salt concentrations. Fungal mycelia were used for gene expression analyses and metabolomics. Three genes (n3, n4 and n6) seem to be related to OTA biosynthesis in Pn856. However, n2 might be involved in OTA degradation. The lack of correlations between the genes studied and OTA in Pn15 could be due to the low OTA levels quantified. The metabolites coniferyl alcohol and 6-hydroxy-8-methoxy-3-methylisochroman were positively correlated to OTA, and 3-methylbutanoic acid and cephalosporolide E might be used as indicators to predict OTA. These results show the complex regulation and influence of PKS proteins on OTA levels. Full article

With increased mycotoxin contamination, the search for eco-friendly biocontrol strategies has become increasingly important. This study aimed to evaluate the efficiency of stilbenoid-enriched Merlot (Me) and Tannat (Ta) vine root extracts, and their major active molecule, vitisin B (VIT), against Aspergillus carbonarius growth and its ochratoxin A (OTA) production using in vitro liquid and solid, and ex vivo grape-berry assays. In liquid assay, Me and Ta (125 mg/L) and VIT (36 mg/L) significantly inhibited extracellular OTA. Additionally, VIT temporarily reduced both fungal growth and total OTA. Transcriptomics showed that VIT and Me slightly induced OTA biosynthesis genes. In solid and ex vivo assays, doses above 1 g/L decreased OTA production by up to 48% without impacting fungal growth. This lack of correlation suggested a distinct regulatory response to extract-induced stress. Importantly, the fungicide tebuconazole showed method-dependent effects. On in vitro solid medium, it significantly inhibited the fungal growth without affecting OTA yield, whereas in ex vivo berry assays, it significantly inhibited both. Our findings emphasize the potential of stilbenoid-enriched extracts as biocontrol agents targeting OTA production, highlighting the value of multi-assay evaluations. Future studies should elucidate their modes of action and optimize their efficacy. Full article

Aspergillus westerdijkiae, a filamentous fungus commonly isolated from pickled vegetables and high-salt condiments, can cause spoilage and produce nephrotoxic ochratoxin A (OTA) under saline conditions. However, its adaptive mechanisms to salt stress remain unclear. To address this, the pickle-derived strain NDX1 was subjected to 0, 1.0, 1.5, and 2.0 mol/L NaCl treatments. Colony growth was assessed after 7 days of incubation on PDA plates supplemented with the respective NaCl concentrations. For physiological indices, mycelia were pre-cultured in salt-free PDB for 5 days, followed by the addition of NaCl to final concentrations (0, 1.0, 1.5, and 2.0 mol/L) and further incubation for 2 days, after which relative electrical conductivity (REC) and malondialdehyde (MDA) content were measured. Colony diameters were recorded to evaluate vegetative growth; REC was determined by conductometry to assess cell membrane permeability; and MDA content was measured via the thiobarbituric acid (TBA) colorimetric method to indicate lipid peroxidation levels. Transcriptome sequencing combined with qRT-PCR validation was employed to identify differentially expressed genes (DEGs) involved in osmotic adaptation. Results showed that low salinity (1.0 mol/L NaCl) promoted growth, while higher concentrations (≥1.5 mol/L NaCl) inhibited it, accompanied by increased REC and decreased MDA, forming a distinctive high-permeability, low-lipid-peroxidation phenotype. A total of 3155 DEGs were detected, mainly associated with the HOG-MAPK cascade, glycerol biosynthesis, and ion transport pathways. Eight key HOG-MAPK genes and 21 glycerol metabolic genes were upregulated in a concentration-dependent manner, with the terminal kinase Hog1 coordinating transcription of downstream effectors governing glycerol synthesis and ion homeostasis. These findings demonstrate that A. westerdijkiae integrates de novo glycerol production and intracellular lipid remodeling via the HOG-MAPK pathway to achieve osmotic adaptation under hypersaline stress. This work identifies potential molecular targets for controlling toxigenic spoilage caused by this species in high-salt fermented foods. Full article

Mycotoxins are one of the biggest threats to global food safety, public health, and economic stability. More than 400 mycotoxins have been found to be secondary metabolites of toxigenic fungi, mostly from the genera Aspergillus, Fusarium, Penicillium, and Alternaria. Aflatoxins (AFs), ochratoxin A (OTA), deoxynivalenol (DON), zearalenone (ZEA), fumonisins (FBs), patulin (PAT), and T-2/HT-2 toxins are the most dangerous to the health of people and animals. Conventional physical and chemical decontamination methods are only partially effective and can reduce food quality, leave toxic residues, or be too expensive for smallholder food systems. Recent studies have shown that the application of lactic acid bacteria (LAB) as a biological detoxification method is a safe, cost-effective, and environmentally friendly option, and has a long history of safe use in fermented foods. Selected strains or taxonomic units have been granted GRAS status by the FDA or QPS (Qualified Presumption of Safety) status by EFSA. However, their use for mycotoxin detoxification still requires strain-level safety assessment and efficacy validation in the intended food matrix. There are several mechanisms by which LAB employ to reduce the bioavailability of mycotoxins in food systems: (i) physical adsorption via cell wall components such as peptidoglycan, teichoic acids, and exopolysaccharides; (ii) enzymatic biotransformation that may produce non-toxic or less-toxic metabolites, though the safety of degradation products requires case-by-case toxicological assessment; (iii) antifungal metabolite production that inhibits fungal growth and mycotoxin biosynthesis; and (iv) competitive exclusion of toxigenic fungi during fermentation. This comprehensive review examines the existing evidence on the detoxification of major food mycotoxins by LAB, with an emphasis on mechanisms, strain-specific efficacy, food-matrix applications, and factors that affect detoxification efficacy. Discussion has also been made of translating in vitro findings to in vivo settings and food-scale applications, alongside regulatory frameworks, current challenges, and future research directions. The review also suggests ways to combine LAB with new technologies, such as encapsulation, genetic engineering, and fermentation optimization, to make food systems safer by synergistically controlling mycotoxins. Full article

This study provides a combined profile of fungal isolates from fresh and dried chili peppers in markets in Guangzhou. Multilocus sequence analysis revealed a wide variety of species, seven of which were reported for the first time from chili pepper (F. annulatum, F. compactum, F. pernambucanum, F. ramsdenii, and F. tardichlamydosporum, P. citrinum and P. steckii). In this research work, quantitative determination using targeted LC–MS/MS of dried chili peppers showed a significantly higher frequency of contamination and higher toxin concentrations than fresh samples. The predominant mycotoxins in dried peppers were DON and FB₁, which were present in all the samples at mean levels of 0.56 µg/g and 0.067 µg/g, respectively. AFB₁ and OTA were present in all dried samples but were detected only occasionally in fresh peppers. ZEN and CIT were detected at lower concentrations, but more prevalent among dried products (63.6% and 81.8% of all samples, respectively). The aflatoxin B₁ (AFB₁) level of 180 µg/kg in dried chili samples was 36 times above the EU maximum limit (5 µg/kg), and the OTA level reached 54 µg/kg, exceeding the EU limit by a factor of 2.7 (20 µg/kg). Statistical analysis also showed that all six mycotoxins were statistically higher in dried pepper than in fresh pepper. In vitro evaluation demonstrated that certain Fusarium isolates synthesized FB₁. At the same time, Penicillium species, including P. citrinum and P. steckii, consistently produced citrinin, confirming the strong influence of growth substrate on toxin biosynthesis. The frequent occurrence and elevated levels of regulated mycotoxins highlight significant public health concerns and underscore the need for improved postharvest handling and drying practices. These findings provide critical baseline data linking fungal diversity with toxin production dynamics, developing essential guidance for targeted mitigation strategies. Full article

The aim of this study was to investigate differences in the dynamics of ochratoxin A (OTA) production by various Aspergillus isolates under different cultivation conditions. Nine strains representing A. westerdijkiae, A. ochraceus, A. sulphureus, A. carbonarius, and A. albertensis were tested on malt extract agar (MEA), Czapek yeast extract agar (CYA), potato dextrose agar (PDA), and yeast extract sucrose agar (YES). Cultivations were performed at 18 °C, 22 °C, 25 °C, and 30 °C, and OTA production was monitored on the 6th, 10th, 14th, 21st, and 30th days using HPLC analysis. OTA yields strongly depended on the producing strain, with significant variability even among isolates of the same species. The most productive strain was A. ochraceus from cereals with a maximum concentration of 848 µg g⁻¹ OTA, followed by two isolates of A. westerdijkiae from grapes of Slovak origin (591 and 479 µg g⁻¹), and A. sulphureus from soil (546 µg g⁻¹). In contrast, A. carbonarius strains showed the weakest OTA production. Across media, YES supported the highest toxin levels, whereas the most favourable cultivation temperatures were 18 °C and 25 °C. Each strain reached its production maximum at different time points, highlighting the strain-specific nature of OTA biosynthesis. Full article

Ochratoxin A (OTA) is a major mycotoxin contaminant in grapes and their products, and Aspergillus carbonarius is its main producer. Controlling the growth of A. carbonarius is therefore critical for mitigating OTA contamination. Plant-derived perillaldehyde, with good antifungal activity and safety, has garnered growing attention. However, current understanding of how perillaldehyde affects A. carbonarius growth and OTA production remains poorly characterized. In this study, we systematically investigated the antifungal and antimycotoxigenic effects of perillaldehyde against A. carbonarius and explored the underlying mechanisms. The results showed that perillaldehyde could alter the mycelial morphology and damage the cell integrity of A. carbonarius. Additionally, perillaldehyde could diminish the total antioxidant capacity and impair the energy metabolism of A. carbonarius. Transcriptome analysis showed that the expressions of all the known conserved OTA biosynthetic genes and two OTA transport-related genes were significantly down-regulated, indicating that perillaldehyde could directly inhibit their expression. In conclusion, perillaldehyde can significantly inhibit OTA production by directly disrupting OTA biosynthesis and transport and inhibiting the growth of A. carbonarius. Thus, perillaldehyde has the potential to be used as a natural fungicide or alternative food preservative in grapes and their products, owing to its strong antifungal and antimycotoxigenic effects on A. carbonarius. Full article

Throughout the process of dry-cured ham, moulds such as P. nordicum, a producer of ochratoxin A (OTA), grow on its surface. The use of combined biocontrol agents (BCAs) is a promising strategy for controlling this hazard. The goal of this study is to assess the effect of D. hansenii, S. xylosus, and P. chrysogenum as BCAs on the metabolome of two strains of P. nordicum and to understand the differences between both strains. Each ochratoxigenic strain was inoculated both individually and in combination with the BCAs onto ham for 30 days under the environmental conditions experienced during traditional ripening. Untargeted metabolomics was performed through mass spectrometry using a Q-Exactive Plus Orbitrap. The BCAs caused alterations in the metabolomes of both ochratoxigenic moulds, mainly in phenylalanine catabolism and the valine, leucine, and isoleucine biosynthesis pathways, although with some differences. In the absence of the BCAs, the metabolomes of both types of P. nordicum were globally changed, despite these being moulds of the same species. In conclusion, these data help us to understand the differences between OTA-producing strains in dry-cured ham and confirm the need to demonstrate the efficacy of BCAs against a wide range of toxigenic moulds before they can be used to minimise OTA contamination in the meat industry. Full article

Histone post-translational modifications (HPTMs) can affect gene expression by rearranging chromatin structure. Between these, histone methylation is one of the most studied in filamentous fungi, and different conserved domains coding for methyltransferase were found in Aspergillus spp. genomes. In this work, the role of the histone methyltransferases AcDot1 and AcRmtA in the mycotoxigenic fungus Aspergillus carbonarius was investigated, obtaining knockout or overexpression mutants through Agrobacterium tumefaciens-mediated transformation (ATMT). A. carbonarius is responsible for grape-bunch rot, representing the major source of ochratoxin A (OTA) contamination on grapes. In vivo conditions, the deletion of Acdot1 or AcrmtA resulted in upregulation of growth when the isolates were cultivated on a minimal medium. The influence of Acdot1 on the OTA biosynthesis was differently affected by culture conditions. On rich media, an increase in OTA accumulation was observed, while on minimal medium, lower OTA concentrations were reported. The deletion of AcrmtA always resulted in lower OTA accumulation. However, the expression of OTA biosynthesis genes was regulated by both histone methyltransferases. Of the six analyzed OTA genes, three of them showed altered expression in the knockout mutants, and otaB and otaR1 were common between both mutants. Furthermore, both AcDot1 and AcRmtA play a role in oxidative stress response, induced by 1 mM hydrogen peroxide, by modulating growth, conidiation and OTA biosynthesis. Neither the deletion nor the overexpression of the Acdot1 or AcrmtA affected virulence, while both the sporulation and OTA production were negatively affected in vivo by the deletion of AcrmtA. Full article

Aflatoxin B1 (AFB1) and Ochratoxin A (OTA) are considered the most important mycotoxins in terms of food safety. The aim of this study was to evaluate the hepatotoxicity of AFB1 and OTA exposure in Wistar rats and to assess the beneficial effect of fermented whey (FW) and pumpkin (P) as functional ingredients through a proteomic approach. For the experimental procedures, rats were fed AFB1 and OTA individually or in combination, with the addition of FW or a FW-P mixture during 28 days. For proteomics analysis, peptides were separated using a LC-MS/MS-QTOF system and differentially expressed proteins (DEPs) were statistically filtered (p < 0.05) distinguishing males from females. Gene ontology visualization allowed the identification of proteins involved in important biological processes such as the response to xenobiotic stimuli and liver development. Likewise, KEGG pathway analysis reported the metabolic routes as the most affected, followed by carbon metabolism and biosynthesis of amino acids. Overall, the results highlighted a strong downregulation of DEPs in the presence of AFB1 and OTA individually but not with the mixture of both, suggesting a synergistic effect. However, FW and P have helped in the mitigation of processes triggered by mycotoxins. Full article

Ochratoxin A (OTA) is a mycotoxin, a common contaminant of grapes and their derivatives, such as wine, and classified as possible human carcinogen (group 2B) by the International Agency for Research on Cancer (IARC). Aspergillus carbonarius is the main producer of OTA in grapes. The stability of the molecule and the poor availability of detoxification systems makes the control of A. carbonarius in vineyards the main strategy used to reduce OTA contamination risk. Several molecular methods are available for A. carbonarius detection, but the correlation between the abundance of fungal population and OTA contamination needs to be improved. This study aimed at the development of innovative quantitative PCR (qPCR) and digital droplet PCR (ddPCR) tools to quantify the mycotoxigenic fractions of A. carbonarius strains on grapes, based on the key gene AcOTApks in the pathway of OTA biosynthesis. Different primers/probe sets were assessed, based on their specificity and sensitivity. This method allowed to quantify up to 100 fg∙µL⁻¹ [cycle of quantification (Cq) = 37] and 10 fg∙µL⁻¹ (0.38 copies∙µL⁻¹) of genomic DNA (gDNA) from A. carbonarius mycelium in qPCR and ddPCR, respectively. The sensitivity as to artificially contaminated must samples was up to 100 conidia (Cq = 38) and 1 conidium (0.13 copies∙µL⁻¹) with qPCR and ddPCR, respectively. Finally, the methods were validated on naturally infected must samples, and the quantification of the fungus was in both cases highly correlated (r = +0.8) with OTA concentrations in the samples. The results showed that both analytical methods can be suitable for improving the sustainable management of OTA contamination in grapes and their derivatives. Full article

Aspergillus carbonarius is considered one of the main fungi responsible for black and sour rot in grapes, as well as the production of the carcinogenic mycotoxin ochratoxin A. The global regulatory methyltransferase protein LaeA controls the production of various secondary metabolites in Aspergillus species, as well as influences sexual and asexual reproduction and morphology. The goal of this study was to investigate the role of the regulatory gene AclaeA in physiology, virulence, and ochratoxin A (OTA) production by deleting this gene from the genome of a wild-type A. carbonarius strain. The evaluation data on the morphological characteristics, virulence experiments in three different grape varieties, and OTA analysis of ΔAclaeA mutants showed that the growth and the OTA production by ΔAclaeA strains were significantly reduced. The mutant strains were also less virulent, producing 40–50% less conidia in three different cultivars of grape berries. Additionally, the gene AclaeA was considerably repressed after the application of three commercial biopesticides (Trianum-P^®, Vacciplant^®, and Serenade^® Max) and the essential oils (EOs) cinnamon, geranium, and thyme, which were also shown to inhibit OTA biosynthesis in A. carbonarius. The study of the regulatory gene AclaeA can contribute to a broader understanding of the role of secondary metabolites during A. carbonarius—grape interactions, as well as the discovery of the mode of action of biological plant protection products and EOs against this mycotoxigenic fungus. Full article

Ochratoxin A (OTA) is a naturally occurring mycotoxin mainly produced by certain species of Aspergillus and Penicillium and is a serious threat to human health and food safety. Previous studies showed that Brevundimonas naejangsanensis ML17 can completely degrade 1 μg/mL of OTA. The aim of this study was to investigate the degradation effect of ML17 at different concentrations of OTA, and specifically, to investigate the mechanism of OTA degradation by ML17. The growth of ML17 was not affected by exposure to 6 μg/mL OTA within 24 h. ML17 could almost completely degrade 12 μg/mL of OTA within 36 h, converting it into the non-toxic OTα and L-phenylalanine. Transcriptomic analysis showed that 275 genes were upregulated, whereas three genes were downregulated in ML17 under the stress of 1 μg/mL OTA. Functional enrichment analysis showed that exposure to OTA enhanced translation, amide and peptide biosynthesis and metabolism, promoted oxidative phosphorylation, and increased ATP production. Further analysis revealed that, when exposed to OTA, ML17 exerted a stress-protective effect by synthesizing large amounts of heat shock proteins, which contributed to the correct folding of proteins. Notably, genes related to antioxidant activity, such as peroxiredoxin, superoxide dismutase, and glutaredoxin 3, were significantly upregulated, indicating that ML17 can resist the toxic effects of OTA through adjusting its metabolic processes, and the enzyme-coding gene0095, having OTA degradation activity, was found to be upregulated. This suggests that ML17 can achieve OTA degradation by regulating its metabolism, upregulating its antioxidant system, and upregulating enzyme-encoding genes with OTA degradation activity. Our work provides a theoretical reference for clarifying the mechanism of OTA degradation by ML17. Full article

The European Rapid Alert System for Food and Feed (RASFF) has shown 1133 notifications for spices and herbs in the last 10 years (2013–2023). The analysis of these notifications indicated that 58.7% (665 alerts) of the alerts corresponded to chemical hazards. Mycotoxins corresponding to aflatoxin B1 (24 alerts) and ochratoxin A (39 alerts) were found in 19.4% of the samples. Due to the presence of these biological hazards in foodstuffs, comprehensive knowledge of their molecular mechanisms of action is required as part of the risk assessment strategy. Aflatoxin B1 (AFB1) is a known potent carcinogen that has been linked to liver cancer in humans and animals. Its toxic effects consist of forming DNA adducts, causing mutations, and interfering with cellular processes. On the other hand, ochratoxin A (OTA) is known to be nephrotoxic, hepatotoxic, carcinogenic, and immunosuppressive in both humans and animals. OTA targets the kidneys and liver, exerting its toxic effects similarly to AFB1, i.e., through DNA damage, oxidative stress, and interference with cellular processes. This communication reviews the molecular mechanism of action underlying the toxicity of AFB1 and OTA found in herbs and spices in Europe, focusing on their biosynthesis, toxicodynamics, interaction with cellular components, and the resulting biochemical pathways leading to adverse health effects. Moreover, it discusses potential strategies for mitigating their presence in spices, emphasizing the importance of hazard characterization for effective risk management and regulation. Full article

Aspergillus carbonarius causes severe decays on berries in vineyards and is among the main fungal species responsible for grape contamination by ochratoxin A (OTA), which is the foremost mycotoxin produced by this fungus. The main goal of this study was to investigate at the transcriptome level the comparative profiles between two table grape varieties (Victoria and Fraoula, the white and red variety, respectively) after their inoculation with a virulent OTA-producing A. carbonarius strain. The two varieties revealed quite different transcriptomic signatures and the expression profiles of the differential expressed genes (DEGs) highlighted distinct and variety-specific responses during the infection period. The significant enrichment of pathways related to the modulation of transcriptional dynamics towards the activation of defence responses, the triggering of the metabolic shunt for the biosynthesis of secondary metabolites, mainly phenylpropanoids, and the upregulation of DEGs encoding phytoalexins, transcription factors, and genes involved in plant–pathogen interaction and immune signaling transduction was revealed in an early time point in Fraoula, whereas, in Victoria, any transcriptional reprogramming was observed after a delay. However, both varieties, to some extent, also showed common expression dynamics for specific DEG families, such as those encoding for laccases and stilbene synthases. Jasmonate (JA) may play a critical modulator role in the defence machinery as various JA-biosynthetic DEGs were upregulated. Along with the broader modulation of the transcriptome that was observed in white grape, expression profiles of specific A. carbonarius genes related to pathogenesis, fungal sporulation, and conidiation highlight the higher susceptibility of Victoria. Furthermore, the A. carbonarius transcriptional patterns directly associated with the regulation of the pathogen OTA-biosynthesis gene cluster were more highly induced in Victoria than in Fraoula. The latter was less contaminated by OTA and showed substantially lower sporulation. These findings contribute to uncovering the interplay beyond this plant–microbe interaction. Full article