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Toxins Sep 2023Maize is frequently contaminated with multiple mycotoxins, especially those produced by and . As mycotoxin contamination is a critical factor that destabilizes global... (Review)
Review
Maize is frequently contaminated with multiple mycotoxins, especially those produced by and . As mycotoxin contamination is a critical factor that destabilizes global food safety, the current review provides an updated overview of the (co-)occurrence of and and (co-)contamination of aflatoxin B1 (AFB1) and fumonisin B1 (FB1) in maize. Furthermore, it summarizes their interactions in maize. The gathered data predict the (co-)occurrence and virulence of and would increase worldwide, especially in European cold climate countries. Studies on the interaction of both fungi regarding their growth mainly showed antagonistic interactions in vitro or in planta conditions. However, the (co-)contamination of AFB1 and FB1 has risen worldwide in the last decade. Primarily, this co-contamination increased by 32% in Europe (2010-2020 vs. 1992-2009). This implies that fungi and mycotoxins would severely threaten European-grown maize.
PubMed: 37756003
DOI: 10.3390/toxins15090577 -
Frontiers in Microbiology 2023RNA interference (RNAi) is one of the important defense responses against viral infection, but its mechanism and impact remain unclear in mycovirus infections. In our...
RNA interference (RNAi) is one of the important defense responses against viral infection, but its mechanism and impact remain unclear in mycovirus infections. In our study, reverse genetics and virus-derived small RNA sequencing were used to show the antiviral responses of RNAi components in infected with Aspergillus flavus partitivirus 1 (AfPV1). qRT-PCR revealed that AfPV1 infection induced the expression of the RNAi components in compared with noninfected . Knock mutants of each RNAi component were generated, but the mutants did not exhibit any obvious phenotypic changes compared with the parental strain. However, after AfPV1 inoculation, production of AfPV1 was significantly less than in the parental strain. Furthermore, sporulation was greater in each AfPV1-infected mutant compared with the AfPV1-infected parental . We also investigated the sensitivity of virus-free and AfPV1-infected RNAi mutants and the parental strain to cell wall stress, osmotic stress, genotoxic stress, and oxidative stress. The mutants of DCLs and AGOs infected by AfPV1 displayed more changes than RDRP mutants in response to the first three stresses. Small RNA sequencing analysis suggested that AfPV1 infection reduced the number of unique reads of sRNA in , although there were many vsiRNA derived from the AfPV1 genome. GO term and KEGG pathway analyses revealed that the functions of sRNA affected by AfPV1 infection were closely related to vacuole production. These results provide a better understanding of the functional role of RNAi in the impact of AfPV1 on the hypovirulence of .
PubMed: 38033556
DOI: 10.3389/fmicb.2023.1252294 -
ACS Omega Jan 2024The goal behind this work is to prepare, characterize, and study the antimicrobial behavior of zirconia (ZrO) nanoparticles (NPs). Various techniques, such as X-ray...
The goal behind this work is to prepare, characterize, and study the antimicrobial behavior of zirconia (ZrO) nanoparticles (NPs). Various techniques, such as X-ray diffraction (XRD), were used for studying the mineralogical structure and crystal size. The microstructure and chemical composition of the prepared particles were analyzed using a scanning electron microscope attached with an energy-dispersive X-ray analysis (EDAX) unit. The antagonistic ability against several Gram-negative and Gram-positive bacteria, including , and , was assessed using the well diffusion method. The results of XRD and scanning electron microscopy (SEM) analyses revealed that the prepared material exhibited the phase of zirconium nanoparticles with particle sizes ranging between 40 and 75 nm. The antimicrobial test results demonstrated that the inhibitory effect increased with the increase of concentration. The inhibitory effect was more pronounced against Gram-positive bacteria, as indicated by the larger size of the inhibitory zone. At a 9% dimethyl sulfoxide (DMSO) concentration, the inhibitory zone had a diameter of 3.50 mm for compared to a diameter of 3.40 mm for . The use of zirconium oxide nanoparticles reduced the diameter of the inhibitory zone when tested against at a 3% DMSO concentration (0.50 mm diameter) and against (0.40 mm diameter). Zirconia nanoparticles were also evaluated for their antifungal activity against several species, including , , and sp. The size of the inhibitory zone indicated the susceptibility of microorganisms to nanozirconium oxide, resulting in a stronger inhibition of sp. at a 100% DMSO concentration (4.50 mm diameter) compared to and (3.00 mm diameter). The results for sp. at a 3% DMSO concentration showed a diameter of the inhibitory zone of 0.90 mm, while for and , the diameter was 0.80 mm. Thus, our findings demonstrate that the zirconium oxide nanoparticles possess the capability to reduce the inhibition zone effectively for both bacterial and fungal activities.
PubMed: 38250396
DOI: 10.1021/acsomega.3c08580 -
Pathogens (Basel, Switzerland) Oct 2023Infections due to the species constitute an important challenge for human health. Invasive aspergillosis represents a life-threatening disease, mostly in patients with... (Review)
Review
Infections due to the species constitute an important challenge for human health. Invasive aspergillosis represents a life-threatening disease, mostly in patients with immune defects. Drugs used for fungal infections comprise amphotericin B, triazoles, and echinocandins. However, in the last decade, an increased emergence of azole-resistant strains has been reported, principally belonging to species. Therefore, both the early diagnosis of aspergillosis and its epidemiological surveillance are very important to establish the correct antifungal therapy and to ensure a successful patient outcome. In this paper, a literature review is performed to analyze the prevalence of antifungal resistance in European countries. Amphotericin B resistance is observed in 2.6% and 10.8% of isolates in Denmark and Greece, respectively. A prevalence of 84% of amphotericin B-resistant isolates is reported in France, followed by 49.4%, 35.1%, 21.7%, and 20% in Spain, Portugal, Greece, and amphotericin B resistance of isolates is observed in Greece and Belgium with a prevalence of 75% and 12.8%, respectively. The prevalence of triazole resistance of isolates, the most studied mold obtained from the included studies, is 0.3% in Austria, 1% in Greece, 1.2% in Switzerland, 2.1% in France, 3.9% in Portugal, 4.9% in Italy, 5.3% in Germany, 6.1% in Denmark, 7.4% in Spain, 8.3% in Belgium, 11% in the Netherlands, and 13.2% in the United Kingdom. The mechanism of resistance is mainly driven by the TR/L98H mutation. In Europe, no in vivo resistance is reported for echinocandins. Future studies are needed to implement the knowledge on the spread of drug-resistant spp. with the aim of defining optimal treatment strategies.
PubMed: 38003770
DOI: 10.3390/pathogens12111305 -
Journal of Fungi (Basel, Switzerland) Jun 2024is notorious for contaminating food with its secondary metabolite-highly carcinogenic aflatoxins. In this study, we found that exogenous nitric oxide (NO) donor could...
is notorious for contaminating food with its secondary metabolite-highly carcinogenic aflatoxins. In this study, we found that exogenous nitric oxide (NO) donor could influence aflatoxin production in . Flavohemoglobins (FHbs) are vital functional units in maintaining nitric oxide (NO) homeostasis and are crucial for normal cell function. To investigate whether endogenous NO changes affect aflatoxin biosynthesis, two FHbs, FHbA and FHbB, were identified in this study. FHbA was confirmed as the main protein to maintain NO homeostasis, as its absence led to a significant increase in intracellular NO levels and heightened sensitivity to SNP stress. Dramatically, FHbA deletion retarded aflatoxin production. In addition, FHbA played important roles in mycelial growth, conidial germination, and sclerotial development, and response to oxidative stress and high-temperature stress. Although FHbB did not significantly impact the cellular NO level, it was also involved in sclerotial development, aflatoxin synthesis, and stress response. Our findings provide a new perspective for studying the regulatory mechanism of the development and secondary mechanism in .
PubMed: 38921422
DOI: 10.3390/jof10060437 -
Journal of Fungi (Basel, Switzerland) Dec 2023is an important fungus that produces aflatoxins, among which aflatoxin B (AFB) is the most toxic and contaminates food and poses a high risk to human health. AFB...
is an important fungus that produces aflatoxins, among which aflatoxin B (AFB) is the most toxic and contaminates food and poses a high risk to human health. AFB interacts with another mycotoxin sterigmatocystin (STC), which is also a precursor of AFB. Herein, we determined the effect of STC on AFB by evaluating transcriptomic and proteomic profiles in the presence or absence of STC by RNA-seq and isobaric tagging, respectively. Overall, 3377 differentially expressed genes were identified by RNA-seq. These genes were mainly associated with the cellular component organisation and biosynthesis, the synthesis of valine, leucine, and isoleucine, and the synthesis of aflatoxin. Clustered genes responsible for AFB biosynthesis exhibited varying degrees of downregulation, and expression was completely suppressed in the experimental group. During proteomic analysis, 331 genes were differentially expressed in response to STC. These differentially expressed proteins were associated with cell parts and catalytic and antioxidant activities. Differentially expressed proteins predominantly participated in metabolic pathways associated with aflatoxin biosynthesis, glycolysis/gluconeogenesis, glutathione metabolism, and carbon metabolism. Notably, the upregulated and downregulated enzymes in carbohydrate and glutathione metabolisms may serve as potential gateways for inhibiting aflatoxin biosynthesis. Moreover, twelve proteins including seven downregulated ones involved in aflatoxin biosynthesis were identified; among them, AflG was the most downregulated, suggesting that it may be the key enzyme responsible for inhibiting aflatoxin synthesis. These findings provide novel insights into control and the mechanisms regulating mycotoxin production.
PubMed: 38132793
DOI: 10.3390/jof9121193 -
Microbiology Spectrum Aug 2023A variety of essential oils and edible compounds have been widely recognized for their antifungal activity in recent years. In this study, we explored the antifungal...
A variety of essential oils and edible compounds have been widely recognized for their antifungal activity in recent years. In this study, we explored the antifungal activity of estragole from Pimenta racemosa against Aspergillus flavus and investigated the underlying mechanism of action. The results showed that estragole had significant antifungal activity against A. flavus, with a minimum inhibitory concentration of 0.5 μL/mL against spore germination. Additionally, estragole inhibited the biosynthesis of aflatoxin in a dose-dependent manner, and aflatoxin biosynthesis was significantly inhibited at 0.125 μL/mL. Pathogenicity assays showed that estragole had potential antifungal activity against A. flavus in peanut and corn grains by inhibiting conidia and aflatoxin production. Transcriptomic analysis showed that the differentially expressed genes (DEGs) were mainly related to oxidative stress, energy metabolism, and secondary metabolite synthesis following estragole treatment. Importantly, we experimentally verified reactive oxidative species accumulation following downregulation of antioxidant enzymes, including catalase, superoxide dismutase, and peroxidase. These results suggest that estragole inhibits the growth and aflatoxin biosynthesis of A. flavus by modulating intracellular redox homeostasis. These findings expand our knowledge on the antifungal activity and molecular mechanisms of estragole, and provide a basis for estragole as a potential agent against A. flavus contamination. Aspergillus flavus contaminates crops and produces aflatoxins, carcinogenic secondary metabolites which pose a serious threat to agricultural production and animal and human health. Currently, control of A. flavus growth and mycotoxin contamination mainly relies on antimicrobial chemicals, agents with side effects such as toxic residues and the emergence of resistance. With their safety, environmental friendliness, and high efficiency, essential oils and edible compounds have become promising antifungal agents to control growth and mycotoxin biosynthesis in hazardous filamentous fungi. In this study, we explored the antifungal activity of estragole from against A. flavus and investigated its underlying mechanism. The results demonstrated that estragole inhibits the growth and aflatoxin biosynthesis of A. flavus by modulating intracellular redox homeostasis.
Topics: Humans; Aspergillus flavus; Reactive Oxygen Species; Antifungal Agents; Aflatoxins; Oils, Volatile; Homeostasis
PubMed: 37289093
DOI: 10.1128/spectrum.01348-23