Synergistic antifungal mechanism of cinnamaldehyde and nonanal against Aspergillus flavus and its application in food preservation

Aspergillus flavus colonization on agricultural products during preharvest and postharvest results in tremendous economic losses. Inspired by the synergistic antifungal effects of essential oils, the aims of this study were to explore the mechanism of combined cinnamaldehyde and nonanal (SCAN) against A. flavus and to evaluate the antifungal activity of SCAN loading into diatomite (DM). Shriveled mycelia were observed by scanning electron microscopy, especially in the SCAN treatment group. Calcofluor white staining, transmission electron microscopy, dichloro-dihydro-fluorescein diacetate staining and the inhibition of key enzymes in tricarboxylic acid cycle indicated that the antifungal mechanism of SCAN against A. flavus was related to the cell wall damage, reactive oxygen species accumulation and energy metabolism interruption. RNA sequencing revealed that some genes involved in antioxidation were upregulated, whereas genes responsible for cell wall biosynthesis, oxidative stress, cell cycle and spore development were significantly downregulated, supporting the occurrence of cellular apoptosis. In addition, compared with the control group, conidia production in 1.5 mg/mL DM/cinnamaldehyde, DM/nonanal and DM/SCAN groups were decreased by 27.16%, 48.22% and 76.66%, respectively, and the aflatoxin B1 (AFB1) contents decreased by 2.00%, 73.02% and 84.15%, respectively. These finding suggest that DM/SCAN complex has potential uses in food preservation.

The potential for reducing aflatoxin B1 contamination of stored peanuts by soil disinfection

Aflatoxins from the fungus Aspergillus flavus (A. flavus) that contaminate stored peanuts is a major hazard to human health worldwide. Reducing A. flavus in soil can decrease the risk of aflatoxins in stored peanuts. In this experiment, we determined whether peanuts grown on soil fumigated with dazomet (DZ), metham sodium (MS), allyl isothiocyanate (AITC), chloropicrin (PIC) or dimethyl disulfide (DMDS) would reduce of the quantity of A. flavus and its toxin's presence. The results of bioassays and field tests showed that PIC was the most effective fumigant for preventing and controlling A. flavus, followed by MS. PIC and MS applied to the soil for 14 d resulted in LD50 values against A. flavus of 3.558 and 4.893 mg kg-1, respectively, leading to almost 100% and 98.82% effectiveness of A. flavus, respectively. Peanuts harvested from fumigated soil and then stored for 60 d resulted in undetectable levels of aflatoxin B1 (AFB1) compared to unfumigated soil that contained 0.64 ug kg-1 of AFB1, which suggested that soil fumigation can reduce the probability of aflatoxin contamination during peanut storage and showed the potential to increase the safety of peanuts consumed by humans. Further research is planned to determine the practical value of our research in commercial practice.

Evaluation of the efficacy of cinnamon oil on Aspergillus flavus and Fusarium proliferatum growth and mycotoxin production on paddy and polished rice: Towards a mitigation strategy

In the present investigation, the effect of cinnamon oil (CO) (10, 30, 50 and 70 %) on the growth rate (mm/day) and aflatoxin B1 (AFB1) and fumonisin B1 (FB1) production of Aspergillus flavus (AF01) and Fusarium proliferatum (FP01) isolates, respectively was determined at optimum water activities (0.95 and 0.99 aw) and temperatures (25, 30 and 35 °C) on paddy and polished rice grains. The results showed that the growth rate, AFB1 and FB1 production of all the fungal isolates decreased with an increase in CO concentrations on both matrices. AF01 and FP01 failed to grow under all conditions on paddy at 50 % of CO concentration whereas both fungi were completely inhibited (No Growth-NG) at 70 % of CO on polished rice. Regarding mycotoxin production, 30 % of CO concentrations could inhibit AFB1 and FB1 production in both matrices (No Detection-ND). In this study, the production of mycotoxins was significantly influenced by cinnamon oil compared to the growth of both fungi. These results indicated the promising potential of CO in improving the quality of rice preservation in post-harvest; however, further investigations should be evaluated on the effects on the qualitative characteristics of grains. Especially, the prospective application of CO in rice storage in industry scales to mitigate mycotoxin contamination need also to be further researched. Moreover, collaboration between researchers, agricultural experts, and food industry should be set up to achieve effective and sustainable strategies for preserving rice.

Melanin depletion affects Aspergillus flavus conidial surface proteins, architecture, and virulence

Melanin is an Aspergillus flavus cell wall component that provides chemical and physical protection to the organism. However, the molecular and biological mechanisms modulating melanin-mediated host-pathogen interaction in A. flavus keratitis are not well understood. This work aimed to compare the morphology, surface proteome profile, and virulence of melanized conidia (MC) and non-melanized conidia (NMC) of A. flavus. Kojic acid treatment inhibited melanin synthesis in A. flavus, and the conidial surface protein profile was significantly different in kojic acid-treated non-melanized conidia. Several cell wall-associated proteins and proteins responsible for oxidative stress, carbohydrate, and chitin metabolic pathways were found only in the formic acid extracts of NMC. Scanning electron microscopy (SEM) analysis showed the conidial surface morphology difference between the NMC and MC, indicating the role of melanin in the structural integrity of the conidial cell wall. The levels of calcofluor white staining efficiency were different, but there was no microscopic morphology difference in lactophenol cotton blue staining between MC and NMC. Evaluation of the virulence of MC and NMC in the Galleria mellonella model showed NMC was less virulent compared to MC. Our findings showed that the integrity of the conidial surface is controlled by the melanin layer. The alteration in the surface protein profile indicated that many surface proteins are masked by the melanin layer, and hence, melanin can modulate the host response by preventing the exposure of fungal proteins to the host immune defense system. The G. mellonella virulence assay also confirmed that the NMC were susceptible to host defense as in other Aspergillus pathogens. KEY POINTS: • l-DOPA melanin production was inhibited in A. flavus isolates by kojic acid, and for the first time, scanning electron microscopy (SEM) analysis revealed morphological differences between MC and NMC of A. flavus strains • Proteome profile of non-melanized conidia showed more conidial surface proteins and these proteins were mainly involved in the virulence, oxidative stress, and metabolism pathways • Non-melanized conidia of A. flavus strains were shown to be less virulent than melanised conidia in an in vivo virulence experiment with the G. melonella model.

Inclusion Complexes of Litsea cubeba (Lour.) Pers Essential Oil into β-Cyclodextrin: Preparation, Physicochemical Characterization, Cytotoxicity and Antifungal Activity

The uses of natural compounds, such as essential oils (EOs), are limited due to their instability to light, oxygen and temperature, factors that affect their application. Therefore, improving stability becomes necessary. The objective of this study was to prepare inclusion complexes of Litsea cubeba essential oil (LCEO) with β-cyclodextrin (β-CD) using physical mixing (PM), kneading (KN) and co-precipitation (CP) methods and to evaluate the efficiency of the complexes and their physicochemical properties using ATR-FTIR, FT-Raman, DSC and TG. The study also assessed cytotoxicity against human colorectal and cervical cancer cells and antifungal activity against Aspergillus flavus and Fusarium verticillioides. The complexation efficiency results presented significant evidence of LCEO:β-CD inclusion complex formation, with KN (83%) and CP (73%) being the best methods used in this study. All tested LCEO:β-CD inclusion complexes exhibited toxicity to HT-29 cells. Although the cytotoxic effect was less pronounced in HeLa tumor cells, LCEO-KN was more active against Hela than non-tumor cells. LCEO-KN and LCEO-CP inclusion complexes were efficient against both toxigenic fungi, A. flavus and F. verticillioides. Therefore, the molecular inclusion of LCEO into β-CD was successful, as well as the preliminary biological results, evidencing that the β-CD inclusion process may be a viable alternative to facilitate and increase future applications of this EO as therapeutic medication, food additive and natural antifungal agent.

Role of mitochondrial farnesyltransferase gene in the prevention of the food spoilage fungi Aspergillus flavus by the antimicrobial natural preservative perillaldehyde

Aspergillus flavus, one of the most widely distributed and abundant genus of Aspergillus worldwide, poses an evident threat as a source of food contamination in grains and cereals. Perillaldehyde (PAE), a volatile essential oil extracted from the stem and leaves of Perilla frutescens L., exhibits potent antifungal activity. In our study, we investigated the role of Cox10, a key enzyme in the heme A synthesis pathway crucial for maintaining mitochondrial function. We found that cox10 is a sensitive gene of A. flavus in response to PAE by gene expression assay and GFP fluorescent localization tagging, and then we found that the deletion of this gene affects the growth and development of A. flavus, but the drug resistance is elevated. Through transcriptome sequencing and its experimental validation, the molecular mechanisms of stress triggered by the deletion of cox10 were further clarified, such as the decrease in intracellular drug content due to the increase in the expression of drug efflux proteins, and the increase in the thickness of cell wall due to the increase in the content of cell wall chitin. Clearly, cox10 plays a critical role in regulating various cellular processes of A. flavus, including growth, reproduction, development, as well as pathogenicity and drug resistance. These significant findings establish a solid theoretical foundation for the development of environmentally friendly, safe, and effective antifungal agents to combat A. flavus contamination.

Structure of Aspergillus flavus populations associated with maize in Greece, Spain, and Serbia: Implications for aflatoxin biocontrol on a regional scale

Aspergillus flavus is the most frequently identified producer of aflatoxins. Non-aflatoxigenic members of the A. flavus L strains are used in various continents as active ingredients of bioprotectants directed at preventing aflatoxin contamination by competitive displacement of aflatoxin producers. The current research examined the genetic diversity of A. flavus L strain across southern Europe to gain insights into the population structure and evolution of this species and to evaluate the prevalence of genotypes closely related to MUCL54911, the active ingredient of AF-X1. A total of 2173L strain isolates recovered from maize collected across Greece, Spain, and Serbia in 2020 and 2021 were subjected to simple sequence repeat (SSR) genotyping. The analysis revealed high diversity within and among countries and dozens of haplotypes shared. Linkage disequilibrium analysis indicated asexual reproduction and clonal evolution of A. flavus L strain resident in Europe. Moreover, haplotypes closely related to MUCL54911 were found to belong to the same vegetative compatibility group (VCG) IT006 and were relatively common in all three countries. The results indicate that IT006 is endemic to southern Europe and may be utilized as an aflatoxin mitigation tool for maize across the region without concern for potential adverse impacts associated with the introduction of an exotic microorganism.

Fatal pulmonary hemorrhage, pneumothorax and skin necrosis caused by IRIS to an Aspergillus flavus infection in a young patient with metamizole associated agranulocytosis

We report the case of a young female with steroid-dependent ulcerative colitis (UC) who developed a complex systemic infection with Aspergillus flavus. This occurred following a UC relapse while vacationing in the Middle East, leading to extended use of metamizole and subsequent agranulocytosis. On her return to Germany, she was hospitalized for neutropenic sepsis and later transferred to our hospital due to persistent cytopenia and suspected Hemophagocytic Lymphohistiocytosis (HLH). Despite initial stabilization with targeted treatment for pulmonary Aspergillus flavus infection, her condition rapidly deteriorated following the onset of an Immune Reconstitution Inflammatory Syndrome (IRIS), which manifested as skin necrosis and pneumothorax after the replenishment of neutrophil granulocytes. The patient eventually died from an unmanageable pulmonary hemorrhage. Microscopy of skin necroses showed a massive presence of Aspergillus flavus, but tissue culture remained negative, suggesting effective antifungal treatment yet delayed phagocytosis due to agranulocytosis. This case underscores the need to consider IRIS in immunosuppressed patients who worsen despite aggressive and appropriately targeted treatment, highlighting its potential beyond the commonly recognized context in HIV-positive patients.

Bacteria-mediated green synthesis of silver nanoparticles and their antifungal potentials against Aspergillus flavus

The best biocontroller Bacillus subtilis produced silver nanoparticles (AgNPs) with a spherical form and a 62 nm size through green synthesis. Using UV-vis spectroscopy, PSA, and zeta potential analysis, scanning electron microscopy, and Fourier transform infrared spectroscopy, the properties of synthesized silver nanoparticles were determined. Silver nanoparticles were tested for their antifungicidal efficacy against the most virulent isolate of the Aspergillus flavus fungus, JAM-JKB-BHA-GG20, and among the 10 different treatments, the treatment T6 [PDA + 1 ml of NP (19: 1)] + Pathogen was shown to be extremely significant (82.53%). TG-51 and GG-22 were found to be the most sensitive groundnut varieties after 5 and 10 days of LC-MS QTOF infection when 25 different groundnut varieties were screened using the most toxic Aspergillus flavus isolate JAM- JKB-BHA-GG20, respectively. In this research, the most susceptible groundnut cultivar, designated GG-22, was tested. Because less aflatoxin (1651.15 g.kg-1) was observed, treatment T8 (Seed + Pathogen + 2 ml silver nanoparticles) was determined to be much more effective. The treated samples were examined by Inductively Coupled Plasma Mass Spectrometry for the detection of metal ions and the fungicide carbendazim. Ag particles (0.8 g/g-1) and the fungicide carbendazim (0.025 g/g-1) were found during Inductively Coupled Plasma Mass Spectrometry analysis below detectable levels. To protect plants against the invasion of fungal pathogens, environmentally friendly green silver nanoparticle antagonists with antifungal properties were able to prevent the synthesis of mycotoxin by up to 82.53%.

Synthesis and toxicological study of chitosan-pirul (Schinus molle L.) essential oil nanoparticles on Aspergillus flavus

In recent years, the study of essential oils as antifungal alternatives and their encapsulation to increase their properties for greater effects has been tested. In this work, nanoparticles of chitosan-Schinus molle L. essential oil (CS-PEO-Np) with a size of 260 ± 31.1 nm were obtained by ionic gelation and evaluated in some growth phases of Aspergillus flavus, a toxigenic fungus. At a concentration of 250 μg/mL of CS-PEO-Np, the A. flavus mycelial growth was inhibited at 97.1% with respect to control, at 96 h of incubation; the germination and viability of spores were inhibited at 74.8 and 40%, respectively, after exposure to 500 μg/mL of these nanomaterials, at 12 h of incubation. The fluorescence images of stained spores with DAPI showed the affectations caused by nanoparticles in the cell membrane, vacuoles and vacuolar content, cell wall, and nucleic acids. For both nanoparticles, CS-Np and CS-PEO-Np, no mutagenic effect was observed in Salmonella Typhimurium; also, the phytotoxic assay showed low-to-moderate toxicity toward seeds, which was dependent on the nanoparticle's concentration. The acute toxicity of CS-PEO-Np to A. salina nauplii was considered low in comparison to CS-Np (control), which indicates that the incorporation of Schinus molle essential oil into nanoparticles of chitosan is a strategy to reduce the toxicity commonly associated with nanostructured materials. The nanoparticulated systems of CS-PEO-Np represent an effective and non-toxic alternative for the control of toxigenic fungi such as A. flavus by delaying the initial growth stage.

SscA is required for fungal development, aflatoxin production, and pathogenicity in Aspergillus flavus

Fungal spores are specialized dormant cells that act as primary reproductive biological particles and exhibit strong viability under extremely harsh conditions. They contaminate a variety of crops and foods, causing severe health hazards to humans and animals. Previous studies demonstrated that a spore-specific transcription factor SscA plays pivotal roles in the conidiogenesis of the model organism Aspergillus nidulans. In this study, we investigated the biological and genetic functions of SscA in the aflatoxin-producing fungus A. flavus. Deletion of sscA showed reduced conidia formation, lost long-term viability, and exhibited more sensitivity to thermal, oxidative, and radiative stresses. The sscA-deficient strain showed increased aflatoxin B1 production in conidia as well as mycelia. Importantly, the absence of sscA affected fungal pathogenicity on crops. Further transcriptomic and phenotypic studies suggested that SscA coordinates conidial wall structures. Overall, SscA is important for conidial formation, maturation and dormancy, mycotoxin production, and pathogenicity in A. flavus.

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.

Biocontrol of Rice Seed-Associated Fungal Pathogens Using Green Synthesis Approaches

Rice (Oryza sativa) is a major cereal crop that balances the food demand of the worldwide population. The crop quality drops daily due to their exposure to biotic and abiotic stresses, especially pathogens. It needs to be improved to maintain the consumption level to cope with increasing population demands for food. The current study was designed to analyze the comparison of the effects of green synthesis approaches on pathogens associated with rice seeds. In this study, essential oils were extracted from Cymbopogon citratus, Thymus vulgaris, and Origanum vulgaris medicinal plants and used as fungicides on fungal strains of Aspergillus spp. T. vulgaris effectively controlled the growth of Aspergillus niger, Aspergillus flavus, and Aspergillus terreus as compared with O. vulgaris and Cymbopogon. Further, silica nanoparticles (SiNPs) were synthesized from rice husk to evaluate their antifungal activities. SiNPs were characterized by ultraviolet-visible spectroscopy with a broad peak at 281.62 nm. Fourier-transform infrared spectroscopy spectrum confirms the presence of Si-H, Si-OH, and Si-O-Si bonds functional groups, and SiO4 tetrahedral coordination unit. X-ray diffraction pattern describes the crystalline structure with a sharp peak at 2θ = 22°. Scanning electron microscopy and energy-dispersive spectroscopy confirmed the spherical shape, size 70-115 nm, and elemental composition with pure silica contents. SiNPs showed no significant antifungal activity against Aspergillus strains. Moreover, Trichoderma was isolated from the rhizosphere of rice fields and showed a surprising antifungal effect against A. terreus, A. niger, and A. flavus. The current study successfully revealed environment-friendly and cost-effective green synthesizing approaches for analyzing biocontrol potential against rice seed-related Aspergillus spp. They will also help to improve pathogen control strategies in other cereals.

Biodegradation capabilities of filamentous fungi in high-concentration heavy crude oil environments

In this comprehensive study, we delved into the capabilities of five fungal strains: Aspergillus flavus, Aspergillus niger, Penicillium chrysogenum, Penicillium glabrum, and Penicillium rubens (the latter isolated from heavy crude oil [HCO]) in metabolizing HCO as a carbon source. Employing a meticulously designed experimental approach, conducted at room temperature (25 °C), we systematically explored various culture media and incubation periods. The results unveiled the exceptional resilience of all these fungi to HCO, with A. flavus standing out as the top performer. Notably, A. flavus exhibited robust growth, achieving a remarkable 59.1% expansion across the medium's surface, accompanied by distinctive macroscopic traits, including a cottony appearance and vibrant coloration. In an effort to further scrutinize its biotransformation prowess, we conducted experiments in a liquid medium, quantifying CO2 production through gas chromatography, which reached its zenith at day 30, signifying substantial bioconversion with a 38% increase in CO2 production. Additionally, we monitored changes in surface tension using the Du Noüy ring method, revealing a reduction in aqueous phase tension from 72.3 to 47 mN/m. This compelling evidence confirms that A. flavus adeptly metabolizes HCO to fuel its growth, while concurrently generating valuable biosurfactants. These findings underscore the immense biotechnological potential of A. flavus in addressing challenges related to HCO, thereby offering promising prospects for bioremediation and crude oil bioupgrading endeavors.

Mechanism of inactivation of Aspergillus flavus spores by dielectric barrier discharge plasma

Dielectric barrier discharge plasma (DBDP) displays strong against fungal spores, while its precise mechanism of spore inactivation remains inadequately understood. In this study, we applied morphological, in vivo and in vitro experiments, transcriptomics, and physicochemical detection to unveil the potential molecular pathways underlying the inactivation of Aspergillus flavus spores by DBDP. Our findings suggested that mycelium growth was inhibited as observed by SEM after 30 s treatment at 70 kV, meanwhile spore germination ceased and clustering occurred. It led to the release of cellular contents and subsequent spore demise by disrupting the integrity of spore membrane. Additionally, based on the transcriptomic data, we hypothesized that the induction of spore inactivation by DBDP might be associated with downregulation of genes related to cell membranes, organelles (mitochondria), oxidative phosphorylation, and the tricarboxylic acid cycle. Subsequently, we validated our transcriptomic findings by measuring the levels of relevant enzymes in metabolic pathways, such as superoxide dismutase, acetyl-CoA, total dehydrogenase, and ATP. These physicochemical indicators revealed that DBDP treatment resulted in mitochondrial dysfunction, redox imbalance, and inhibited energy metabolism pathways. These findings were consistent with the transcriptomic results. Hence, we concluded that DBDP accelerated spore rupture and death via ROS-mediated mitochondrial dysfunction, which does not depend on cell membranes.

Fungal Otitis Externa (Otomycosis) Associated with Aspergillus Flavus: A Case Image

A 48-year-old man presented with a chief complaint of intermittent right ear otorrhea of several-month duration, occasional otalgia and progressive unilateral hearing impairment. He also reported frequent episodes of headache and pressure in the sinuses and maxilla. Previous systemic treatment with antibiotics failed to alleviate the symptoms. A head/neck CT showed completely normal mastoid, middle ear and external auditory canal regions without any evidence of opacification or bone erosion. Otoscopic examination of the right ear disclosed aggregates of dried, brown, fibrillar material and debris occluding the external auditory canal and obstructing the otherwise intact tympanic membrane. Dilation of the external auditory canal or thickening of the tympanic membrane were not appreciated. The canal was debrided and the fibrillar material was placed in formalin. Histopathologic examination revealed numerous branching, septated fungal hyphae organized in densely-packed clusters. In other areas, the fungal hyphae abutted or were attached to lamellated collections of orthokeratin. As highlighted by GMS staining, the fungi were morphologically compatible with Aspergillus species. The clinicopathologic findings supported a diagnosis of fungal otitis externa, while the numerous anucleate squamous cells were compatible with colonization of an underlying, probably developing, cholesteatoma. Culture of material isolated from the external auditory canal confirmed the presence of Aspergillus flavus. In this illustrative case, we present the main clinical and microscopic characteristics of Aspergillus-related otomycosis developing in the setting of a tautochronous cholesteatoma.

Effects of zinc oxide nanocomposites on microorganism growth and protection of physicochemical quality during maize storage

Maize moldy and spoilage due to microbial growth is a significant challenge in grain storage. This study aimed to evaluate the effectiveness of a zinc oxide nanocomposite, ZnO@mSiO2, prepared in our previous research, in inhibiting mold growth and preserving maize cell quality. The results demonstrated that ZnO@mSiO2 could effectively inhibit the growth of dominant microorganism, Aspergillus flavus, Talaromyces variabilis, Penicillium citrinum and Fusarium graminearum, in maize storage. Aspergillus flavus was selected as the model fungus, ZnO@mSiO2 effectively disrupted fungal hyphae structure, leading to reduced hyphal mass and inhibited spore germination. The inhibitory effect of ZnO@mSiO2 on mold growth was concentration-dependent. However, the ZnO@mSiO2 at an appropriate concentration (not exceeding 3.0 g/kg) preserved the integrity of maize cell membranes and enhancing the antioxidant activity within maize cells. The findings highlight the potential of ZnO@mSiO2 as an effective protectant to inhibit mold growth and preserve maize quality during storage.

Characterization of Aspergillus section Flavi associated with stored grains

Increased frequencies of Aspergillus section Flavi and aflatoxins in cereal grains have been seen in recent years due to changes in climate circumstances, such as high temperatures and drought. To assess the microbiological risks of contamination, it is critical to have a reliable and accurate means of identifying the fungi. The main goal of this study was to characterize Aspergillus species from section Flavi obtained from twenty-three samples of barley and maize grains, gathered from different markets in Qena, Egypt, using morphological and molecular techniques. Twenty-three isolates were chosen, one isolate from each sample; they were identified as A. aflatoxiformans (4 isolates), A. flavus (18), and A. parasiticus (1). The existence of four aflatoxin biosynthesis genes was also investigated in relation to the strains' ability to produce total aflatoxins and aflatoxin B1, focusing on the regulatory gene aflR and the structural genes aflD and aflM. All strains producing aflatoxins were linked to the presence of aflR1 and/or aflR2, except two isolates that exhibited aflatoxins but from which aflR1 or aflR2 were not detected, which may be due to one or more missing or unstudied additional genes involved in aflatoxin production. AflD and aflM genes were amplified by 10 and 9 isolates, respectively. Five samples of barley and maize were contaminated by aflatoxins. Fifteen isolates were positive for producing total aflatoxins in the range of 0.1-240 ppm. Antagonistic activity of Trichoderma viride against A. flavus (F5) was assessed at 31.3%. Trichoderma reduced total aflatoxins in all treated seeds, particularly those subjected to Trichoderma formulation.

Potential molecular mechanism of reuterin on the inhibition of Aspergillus flavus conidial germination: An in silico study

Reuterin is a natural antifungal agent derived from certain strains of Limosilactobacillus reuteri. Our previous study revealed that 6 mM reuterin inhibited completely the conidial germination of aflatoxigenic Aspergillus flavus. This study investigated the potential molecular mechanism of reuterin in inhibiting A. flavus conidial germination, which was pre-assumed that it correlated to the inhibition of some essential enzyme activity involved in conidial germination, specifically 1,3-β-glucan synthase, chitin synthase, and catalases (catalase, bifunctional catalase-peroxidase, and spore-specific catalase). The complex of 1,3-β-glucan synthase and chitin synthase with reuterin had a lower binding affinity than that with the substrate. Conversely, the complex of catalases with reuterin had a higher binding affinity than that with the substrate. It was suggested that 1,3-β-glucan synthase and chitin synthase tended to bind the substrate rather than bind reuterin. In contrast, catalases tended to bind reuterin rather than bind the substrate. Therefore, reuterin could be a potential inhibitor of catalases but may not be an inhibitor of 1,3-β-glucan synthase and chitin synthase. In this in silico study, we predicted that the potential molecular mechanism of reuterin in inhibiting A. flavus conidial germination was due to the inhibition of catalases activities by competitively binding to the enzymes active sites, thus resulting in the accumulation of reactive oxygen species in cells, leading to cells damage. PRACTICAL APPLICATION: This in silico study revealed that reuterin is a potential inhibitor of catalases in A. flavus, thereby interfering with the antioxidant system during conidial germination. This finding shows that reuterin can be used as an antifungal agent in food or agricultural products, inhibiting conidial germination completely.

essential oil, against Aspergillus flavus in postharvest wheat

Plant volatile organic compounds (VOCs) with antimicrobial activity could potentially be extremely useful fumigants to prevent and control the fungal decay of agricultural products postharvest. In this study, antifungal effects of volatile compounds in essential oils extracted from Origanum vulgare L. against Aspergillus flavus growth were investigated using transcriptomic and biochemical analyses. Carvacrol was identified as the major volatile constituent of the Origanum vulgare L. essential oil, accounting for 66.01 % of the total content. The minimum inhibitory concentrations of carvacrol were 0.071 and 0.18 μL/mL in gas-phase fumigation and liquid contact, respectively. Fumigation with 0.60 μL/mL of carvacrol could completely inhibit A. flavus proliferation in wheat grains with 20 % moisture, showing its potential as a biofumigant. Scanning electron microscopy revealed that carvacrol treatment caused morphological deformation of A. flavus mycelia, and the resulting increased electrolyte leakage indicates damage to the plasma membrane. Confocal laser scanning microscopy confirmed that the carvacrol treatment caused a decrease in mitochondrial membrane potential, reactive oxygen species accumulation, and DNA damage. Transcriptome analysis revealed that differentially expressed genes were mainly associated with fatty acid degradation, autophagy, peroxisomes, the tricarboxylic acid cycle, oxidative phosphorylation, and DNA replication in A. flavus mycelia exposed to carvacrol. Biochemical analyses of hydrogen peroxide and superoxide anion content, and catalase, superoxide dismutase, and glutathione S-transferase activities showed that carvacrol induced oxidative stress in A. flavus, which agreed with the transcriptome results. In summary, this study provides an experimental basis for the use of carvacrol as a promising biofumigant for the prevention of A. flavus contamination during postharvest grain storage.

Spherical Fe2O3 nanoparticles inhibit the production of aflatoxins (B1 and B2) and regulate total soluble solids and titratable acidity of peach fruit

Aflatoxin is a group I carcinogen and causes significant public health and food safety risks, throughout the world. This study was carried out to assess the levels of aflatoxin contamination in diseased peach (Prunus persica L.) fruit and their control using myco-synthesized iron oxide nanoparticles (Fe2O3 NPs). Diseased peach fruit were diagnosed to be infected with Aspergillus flavus. The isolated pathogen was cultured under UV light (365 nm) and exposed to ammonium hydroxide (31 %) vapors, which confirmed its ability to produce aflatoxin. For the control of this disease, Fe2O3 NPs were synthesized in the filtrate of a biocontrol fungus (Trichoderma harzianum) and characterized before analyzing their potential in disease control. FTIR spectrum described the presence of capping and reducing agents (secondary amines, alcohol, alkyne and aromatic compounds) on the surface of Fe2O3 NPs. X-ray Diffraction (XRD) described the crystalline size (7.78), while the spherical shape of Fe2O3 NPs was described by the SEM analysis. The EDX spectrum indicated the successful formation of Fe2O3 NPs by showing strong signals of iron (74.38 %). All concentrations displayed mycelial growth inhibition, in vitro and the greatest growth reduction (65.4 %) was observed at 1 mg/ml concentration of NPs. At the same concentration of Fe2O3 NPs, significant control of fruit rot of peach was also observed, in vivo. Treatment of Fe2O3 NPs maintained higher soluble solids, sucrose, total sugar, ascorbic acid, titratable acidity and firmness of peach fruit. Diseased fruit were further investigated for the presence and detection of aflatoxins. All three methods viz. thin layer chromatography (TLC), enzyme-linked immunosorbent assay (ELISA) and high-performance liquid chromatography (HPLC) confirmed a higher production of aflatoxins in control plants, while this production was significantly reduced in Fe2O3 NPs-treated peach fruit.

Mechanisms of methyl 2-methylbutyrate suppression on Aspergillus flavus growth and aflatoxin B1 biosynthesis

Aspergillus flavus and subsequently produced carcinogenic aflatoxins frequently contaminate postharvest food crops, resulting in a threat to global food safety. Chemical preservatives are currently the main antifungal agents. However, fungal resistance effect, biological toxicity, and environmental contamination limit their practical applications. The application of natural volatile organic compounds has great potential for controlling fungal and mycotoxin contamination of postharvest food crops. This study therefore investigated the antifungal and anti-aflatoxigenic activities of the volatile compound, methyl 2-methylbutyrate (M2M), against Aspergillus flavus and its potential mechanisms. M2M effectively inhibited A. flavus mycelia growth, with a minimum inhibitory concentration of 2.0 μL/mL. Moreover, M2M also suppressed aflatoxin production, sclerotia production, and the pathogenicity on peanut and corn flour. RNA-Seq results showed that 2899 differentially expressed genes (DEGs), and DEGs involved in ergosterol synthesis, cell wall structure, glycolysis, citric acid cycle, mitogen activated protein kinase signaling pathway, DNA replication, and aflatoxin biosynthesis, were down-regulated in A. flavus. Further studies showed that M2M strongly damaged the cell membrane and cell wall integrity, reduced ATP levels, and induced reactive oxygen species (ROS) accumulation and DNA damage. Notably, a GATA type zinc finger transcription factor, AfSreA (AFLA_132440), which is essential for A. flavus growth and aflatoxin production, was identified. The growth and aflatoxin yield in the ΔAfSreA strain decreased by 94.94 % and 71.82 %, respectively. Additionally, deletion of AfSreA destroyed cell wall integrity and decreased expressions of genes involved in aflatoxin biosynthesis. Taken together, our results identified the antifungal and anti-aflatoxigenic mechanisms of M2M against A. flavus, and confirmed the potential of M2M in protecting peanut and corn from fungal contamination.

A multivariate algorithm for identifying contaminated peanut using visible and near-infrared hyperspectral imaging

In this study, a novel uniform manifold approximation and projection combined-improved simultaneous optimization genetic algorithm-convolutional neural network (UMAP-ISOGA-CNN) algorithm was proposed. The improved simultaneous optimization genetic algorithm (ISOGA) combined with convolutional neural network (CNN) to optimize the architecture, hyperparameters, and optimizer of the CNN model simultaneously. Additionally, a uniform manifold approximation and projection (UMAP) method was used to visualize the feature space of all feature layers of the ISOGA-CNN model. The UMAP-ISOGA-CNN algorithm combined with visible and near-infrared hyperspectral imaging was used to identify peanut kernels contaminated with Aspergillus flavus and to distinguish their storage time, which is essential for the food industry to monitor the freshness of products. Overall, the UMAP-ISOGA-CNN algorithm provides useful insights into the feature space of the ISOGA-CNN model, contributing to a better understanding of the model's internal mechanisms. This study has practical implications for the food industry and future research on deep learning optimization.

Evaluation of the Susceptibility of Lotus Seeds (Nelumbo nucifera Gaertn.) to Aspergillus flavus Infection and Aflatoxin Contamination

The seeds of lotus (Nelumbo nucifera Gaertn.) have been used as significant medicinal and nutritional ingredients worldwide. The abundant proteins and polysaccharides in lotus seeds make them susceptible to contamination by aflatoxin (AF), a fungal toxic metabolite. This study was conducted to investigate the susceptibility of lotus seeds at different stages of ripening to AF contamination, as well as the mechanism of the contamination. Seven groups of lotus receptacles with seeds at different ripening stages (A-G, from immature to mature) were used for the experiment. Spores of Aspergillus flavus, an AF producer, were inoculated on the water-gap area of the seeds in each receptacle. Then, each receptacle was covered with a sterilized bag, and its stalk part was soaked in water containing a life-prolonging agent, after which it was kept at room temperature for 14 days. The AF content of each whole inoculated seed from the A-G groups and that of each seed part (pericarp, cotyledon, and embryo) from the D and E groups were determined using high-performance liquid chromatography. Microtome sections were prepared from the samples and observed under a light microscope and scanning electron microscope. The seeds from the A and D groups had higher AF contents than the seeds from the B, C, E, F, and G groups, indicating that the condition of the water-gap area and the development of the embryo and cotyledon parts of the seeds are associated with AF contamination.

Synthesis, characterization, synergistic inhibition, and biological evaluation of novel Schiff base on 304 stainless steel in acid solution

A novel Schiff base [4-(morpholin-4-yl) benzylidenyl]thiosemicarbazide (MBT) was created by reaction condensation. The molecules of the products were verified by IR, 1HNMR, MS, and elemental techniques. The synergistic effect of KI with novel MBT on 304 stainless steel (SS) in acidic has been investigated experimentally and theoretically using DFT. The findings demonstrate that restriction efficacy on 304 SS improved with rising inhibitor concentrations, and this benefit was attributed to synergy when KI was injected. From EIS results, IE % increased with a higher concentration of MBT only and MBT + KI (from 100 to 600 ppm). MBT maximum IE % was 84.98%, at 600 ppm. MBT + KI, due to the I- ions synergistic effect, showed an IE% of about 95.48%, at 600 ppm. The adsorptions of MBT and MBT + KI on the surfaces of 304 SS are strongly fitted Langmuir adsorption isotherms. Thermodynamic parameters (Kads, ΔG0ads) were utilized. According to polarization findings, MBT behaves as a mixed-category antagonist. The Schiff base MBT was screened for its in vitro antimicrobial activities against some strains of bacteria and fungi. The result revealed that MBT proved to be an excellent candidate as a fungal agent being able to inhibit Aspergillus flavus.

Evaluation of antifungal activity of natural compounds on growth and aflatoxin B1 production of Aspergillus parasiticus and Aspergillus flavus

BACKGROUND

Aspergillus species cause broad spectrum infections especially invasive lethal infections in immunocompromised patients. This study aimed to assess the antifungal activity of plants and compounds including Aloe vera, Thyme, carvacrol, and nano-encapsulation of carvacrol on the growth and production of aflatoxin B1 production by Aspergillus parasiticus and Aspergillus flavus.

METHODS AND RESULTS

Minimum inhibitory concentrations of extracts Aloe vera, Thyme, carvacrol, and nanocarvacrol, and fluconazole as a control were determined according to Clinical and Laboratory Standards Institute by serial microdilution protocol. Then, the effect of inhibitory concentrations of these compounds on the aflatoxin B1 production level was evaluated by real-time PCR and high-performance liquid chromatography. Our results indicate that the Aspergillus parasiticus and Aspergillus flavusare sensitive to selected plants and compounds.

CONCLUSION

Our findings showed that the compounds are appropriate alternative candidates against growth and production of aflatoxin of Aspergillus spp.

Nursery pigs fed with feed contaminated by aflatoxin B1 (Aspergillus flavus) and anti-mycotoxin blend: Pathogenesis and negative impact on animal health and weight gain

The present study aimed to evaluate whether a moderate dose of aflatoxin B1 in pigs' diet interferes with pigs' growth and health in the nursery phase and whether an anti-mycotoxin mixture minimizes the adverse effects of the toxin. One blend with Saccharomyces cerevisiae lysate, zeolite, silicon dioxide, propylene glycol, Carduus marianus extract, soy lecithin, and carbonate was used as an anti-mycotoxin. Four treatments, with six repetitions per treatment and three pigs/pen: Afla0-AntiMyc0 - negative control (without aflatoxin); Afla500-AntiMyc0 - positive control (500 ppb of aflatoxin); Afla0-AntiMyc1000 - 1000 mg/kg of anti-mycotoxin blend; Afla500-AntiMyc1000 - 500 ppb aflatoxin +1000 mg/kg of anti-mycotoxin blend. It was observed that pigs in the positive control (Afla500-AntiMyc0) had lower body weight and weight gain when compared to the other treatments during the experimental period. Also, pigs from Afla500-AntiMyc0 had lower feed intake between days 1-20 and 1 to 30 than Afla0-AntiMyc0. The pigs from Afla500-AntiMyc0 had higher levels of liver enzymes aspartate aminotransferase and alanine aminotransferase compared to other treatments. The pigs from Afla500-AntiMyc0 had higher villus height than the other treatments, while the folded size was smaller in this treatment. Crypts were deeper in the intestines of pigs in both treatments that consumed aflatoxin. In general, it is concluded that the intake of aflatoxin B1 by nursery pigs has negative impacts on the health and, consequently, the animals' growth performance; however, the addition of the contaminated feed with an anti-mycotoxin blend was able to protect the pigs, minimizing the adverse effects caused by the mycotoxin.

Encapsulation of carvone in chitosan nanoemulsion as edible film for preservation of slice breads against Aspergillus flavus contamination and aflatoxin B1 production

Aspergillus flavus is a common fungus causing bread spoilage by aflatoxin B1 (AFB1) production. Essential oil components are considered as effective antifungal agent; however, volatility and oxidative-instability limited their practical applications. The aim of this study was to fabricate novel chitosan nanoemulsion film incorporating carvone (carvone-Ne) for protection of bread slices against A. flavus and AFB1 contamination in storage conditions. The nanoemulsion was characterized by SEM, DLS, XRD, and FTIR analyses accompanying with sustained delivery of carvone. The carvone-Ne displayed better inhibition of A. flavus (0.5 µL/mL) and AFB1 production (0.4 µL/mL) over unencapsulated carvone along with promising antioxidant activity (p < 0.05). Destruction of ergosterol, mitochondrial-membrane-potential, ions leakage, deformities in methylglyoxal biosynthesis, and in-silico interaction of carvone with Afl-R protein emphasized the antifungal and antiaflatoxigenic mechanisms of action. Further, in-situ preservation potentiality of Carvone-Ne in bread slices with improved gas compositions, and acceptable sensory qualities strengthen its application as innovative packaging material for food preservation.

Discrimination of toxigenic and non-toxigenic Aspergillus flavus in wheat based on nanocomposite colorimetric sensor array

A novel method was developed for the early detection of wheat infected with Aspergillus flavus (A. flavus) using a nanocomposite colorimetric sensors array (CSA). LC-MS analysis revealed the presence of Aflatoxin B1 (AFB1) and Aflatoxin B2 (AFB2) on day seven, demonstrating mycotoxin variabilities in infected wheat. HS-SPME-GC-MS analysis detected 2-methylbutyral, a gas exclusively associated with toxigenic A. flavus. The CSA was modified using three nanoparticles of MOF and successfully used to detect the wheat infected with A. flavus. Discrimination of different types of infected wheat samples was achieved using the RGB difference map and Principal Component Analysis (PCA) model. Additionally, the Linear Discriminant Analysis (LDA) model accurately predicted the presence of toxigenic A. flavus at various stages of infection. These findings highlight the promising capabilities of nanocomposite CSA for early-stage detection of A. flavus infection in wheat.

Utility of a loop-mediated isothermal amplification detection kit to diagnose chronic pulmonary aspergillosis

BACKGROUND

Diagnosing chronic pulmonary aspergillosis (CPA) is still challenging, and infection with Aspergillus spp. must be detected early. The aim of this study was to evaluate, for the first time, the usefulness of a new loop-mediated isothermal amplification (LAMP) test kit in diagnosing CPA.

METHODS

This cross-sectional study was performed at the National Hospital Organization Kinki-Chuo Chest Medical Center. We prospectively enrolled patients with and without CPA. The primary outcomes of this study were the sensitivity and specificity of LAMP for the diagnosis of CPA.

RESULTS

In total, 34 patients with CPA and 21 without CPA (the control group) were enrolled between October 2019 and December 2021. Among the 34 patients with CPA, cultures were positive for CPA in 16 and negative for 18. The majority of fungi isolated in sputum were A. fumigatus in 15 specimens; Aspergillus flavus was isolated in 1) LAMP demonstrated 55.9% sensitivity (95% confidence interval [CI] 37.9-72.8) and 100.0% specificity (95% CI 77.2-100.0).

CONCLUSION

LAMP is an acceptable tool for diagnosing CPA, and its application in clinical practice necessitates more studies.

The biodiversity of Aspergillus flavus in stored rice grain leads to a decrease in the overall aflatoxin B1 production in these species

Aspergillus flavus is a significant fungus that poses a threat to food safety by producing mycotoxins in various crops. In this study, A. flavus isolates were obtained from storage rice collected from seven provinces in southern China, and their AFB1 production, biosynthesis genes presence, and diversity were detected. Results showed that 56 out of the 81 A. flavus isolates produced detectable levels of AFB1, and 71 isolates (87.6 %) possessed aflR gene in their AF synthesis gene cluster, while only 41 isolates (50.6 %) had the ver-1 gene present. Genetic diversity analysis using inter-simple sequence repeats (ISSR) markers revealed seven main clusters among the isolates and the genetic similarity coefficients of 81 A. flavus isolates ranged from 0.53 to 1.00. Additionally, coculture assays were conducted using two toxigenic and two atoxigenic isolates from the same grain depot to investigate the effect of intraspecific inhibition on AFB1 production and to assess the AFB1 contamination risk of storage rice. The in situ results demonstrated that the atoxigenic isolates effectively inhibited the AFB1 contamination of toxigenic isolates. These findings provide insight into the genetic diversity of A. flavus isolates populations and highlight the potential food safety hazards of them in stored rice grain in China.

The KdmB-EcoA-RpdA-SntB (KERS) chromatin regulatory complex controls development, secondary metabolism and pathogenicity in Aspergillus flavus

The filamentous fungus Aspergillus flavus is a plant and human pathogen predominantly found in the soil as spores or sclerotia and is capable of producing various secondary metabolites (SM) such as the carcinogenic mycotoxin aflatoxin. Recently, we have discovered a novel nuclear chromatin binding complex (KERS) that contains the JARID1-type histone demethylase KdmB, a putative cohesion acetyl transferase EcoA, a class I type histone deacetylase RpdA and the PHD ring finger reader protein SntB in the model filamentous fungus Aspergillus nidulans. Here, we show the presence of the KERS complex in A. flavus by immunoprecipitation-coupled mass spectrometry and constructed kdmBΔ and rpdAΔ strains to study their roles in fungal development, SM production and histone post-translational modifications (HPTMs). We found that KdmB and RpdA couple the regulation of SM gene clusters with fungal light-responses and HPTMs. KdmB and RpdA have opposing roles in light-induced asexual conidiation, while both factors are positive regulators of sclerotia development through the nsdC and nsdD pathway. KdmB and RpdA are essential for the productions of aflatoxin (similar to findings for SntB) as well as cyclopiazonic acid, ditryptophenaline and leporin B through controlling the respective SM biosynthetic gene clusters. We further show that both KdmB and RpdA regulate H3K4me3 and H3K9me3 levels, while RpdA also acts on H3K14ac levels in nuclear extracts. Therefore, the chromatin modifiers KdmB and RpdA of the KERS complex are key regulators for fungal development and SM metabolism in A. flavus.

Transcriptomic and biochemical analyses revealed antifungal mechanism of trans-anethole on Aspergillus flavus growth

Plant volatile compounds have great potential for preventing and controlling fungal spoilage in post-harvest grains. Recently, we have reported the antifungal effects of trans-anethole, the main volatile constituent of the Illicium verum fruit, on Aspergillus flavus. In this study, the inhibitory mechanisms of trans-anethole against the growth of A. flavus mycelia were investigated using transcriptomic and biochemical analyses. Biochemical and transcriptomic changes in A. flavus mycelia were evaluated after exposure to 0.2 μL/mL trans-anethole. Scanning electron microscopy showed that trans-anethole treatment resulted in the surface wrinkling of A. flavus mycelia, and calcofluor white staining confirmed that trans-anethole treatment disrupted the mycelial cell wall structure. Annexin V-fluorescein isothiocyanate/propidium iodide double staining suggested that trans-anethole induced apoptosis in A. flavus mycelia. Reduced mitochondrial membrane potential and DNA damage were observed in trans-anethole-treated A. flavus mycelia using 5,5',6,6'-tetrachloro-1,1',3,3'-tetraethyl-imidacarbocyanine and 4',6-diamidino-2-phenylindole staining, respectively. 2',7'- Dichloro-dihydro-fluorescein diacetate staining and biochemical assays demonstrated that trans-anethole treatment cause the accumulation of reactive oxygen species in the A. flavus mycelia. Transcriptome results showed that 1673 genes were differentially expressed in A. flavus mycelia exposed to trans-anethole, which were mainly associated with multidrug transport, oxidative phosphorylation, citric acid cycle, ribosomes, and cyclic adenosine monophosphate signaling. We propose that trans-anethole can inhibit the growth of A. flavus mycelia by disrupting the cell wall structure, blocking the multidrug transport process, disturbing the citric acid cycle, and inducing apoptosis. This study provides new insights into the inhibitory mechanism of trans-anethole on A. flavus mycelia and will be helpful for the development of natural fungicides. KEY POINTS: • Biochemical analyses of A. flavus mycelia exposed to trans-anethole were performed • Transcriptomic changes in trans-anethole-treated A. flavus mycelia were analyzed • An inhibitory mechanism of trans-anethole on the growth of A. flavus mycelia was proposed.

Insights into the antimicrobial efficacy of Coleus aromaticus essential oil against food-borne microbes: Biochemical and molecular simulation approaches

The study reported the antimicrobial efficacy of chemically characterized Coleus aromaticus essential oil (CEO) against food-borne bacteria, molds (Aspergillus flavus), aflatoxin B1 (AFB1) and explored its mechanism of action using biochemical and molecular simulation approaches. The chemical profile of CEO was explored by Gas chromatography-mass spectrometry (GC-MS) analysis, which revealed thymol (46.0%) as the major compound. The minimum inhibitory concentration values of CEO for bacterial species Escherichia coli, Salmonella enterica, Bacillus cereus, and Shigella flexneri was found to be 0.9 μl/ml, 0.7 μl/ml, 0.16 μl/ml, and 0.12 μl/ml respectively. The MIC value for A. flavus and AFB1 contamination was 0.6 μl/ml. The DPPH radical scavenging activity of CEO was recorded with IC50 0.32 μl/ml. Biochemical and computational approaches (docking and dynamics simulation) have been performed to explore the multi-faceted antimicrobial inhibitory effects of CEO at the molecular level, which shows the impairment in membrane functioning, leakage of cellular contents, release of 260-nm absorbing materials, antioxidative defense, carbon catabolism and vital genes (7AP3, Nor1, Omt1, and Vbs). The findings indicated that CEO could be used as natural antimicrobial agents against food-spoilage bacteria, A. flavus and AFB1 contamination to extend the shelf-life of food product and prevention of food-borne diseases.

Pathogenic fungi shape the fungal community, network complexity, and pathogenesis in kiwifruit

Kiwifruit decay caused by endophytic fungi is affected by exogenous pathogens that trigger changes in fungal community composition and interact with the endophytic fungal community. Four fungal pathogens of kiwifruit were identified. These were Aspergillus japonicus, Aspergillus flavus, Botryosphaeria dothidea, and Penicillium oxalicum. Except for P. oxalicum, the remaining three species represent newly described pathogens of kiwifruit. All four fungal species caused disease and decay in mature kiwifruit. Results of the fungal community analysis indicated that three pathogens that A. japonicus, A. flavus and P. oxalicum were the most dominant, however, other fungal species that did not cause disease symptoms were also present. Positive interactions between fungal species were found in asymptomatic, symptomatic, and infected kiwifruit. The ability of all four pathogens to infect kiwifruit was confirmed in an inoculation experiment. The presence of any one of the four identified pathogens accelerated decay development and limited the postharvest longevity of harvested kiwifruit. Results of the study identified and confirmed the ability of four fungal species to infect and cause decay in harvested kiwifruit. Changes in the structure and composition of the kiwifruit microbiome during the decay process were also characterized. This provides a foundation for the further study of the microbiome of kiwifruit and their involvement in postharvest diseases.

Tracking new insights into antifungal and anti-mycotoxigenic properties of a biofilm forming Pediococcus pentosaceus strain isolated from grain silage

The present study offers detailed insights into the antifungal and anti-mycotoxigenic potential of a biofilm forming lactic acid bacterium (Pediococcus pentosaceus) against one atoxigenic (Aspergillus flavus) and two toxigenic (Aspergillus nomius and Fusarium verticillioides) fungal strains. The antifungal effect of P. pentosaceus LBM18 strain was initially investigated through comparative analysis of fungi physiology by macroscopic visual evaluations and scanning electron microscopy examinations. The effects over fungal growth rate and asexual sporulation were additionally accessed. Furthermore, analytical evaluations of mycotoxin production were carried out by HPLC-MS/MS to provide insights on the bacterial anti-mycotoxigenic activity over fungal production of the aflatoxins B1, B2, G1 and G2 as well as fumonisins B1 and B2. Finally, reverse transcription quantitative real-time PCR (RT-qPCR) analysis was employed at the most effective bacterial inoculant concentration to evaluate, at the molecular level, the down-regulation of genes aflR, aflQ and aflD, related to the biosynthesis of aflatoxins by the strain of Aspergillus nomius. The effects over mycotoxin contamination were thought to be result of a combination of several biotic and abiotic factors, such as interaction between living beings and physical-chemical aspects of the environment, respectively. Several possible mechanisms of action were addressed along with potentially deleterious effects ascribing from P. pentosaceus misuse as biopesticide, emphasizing the importance of evaluating lactic acid bacteria safety in new applications, concentrations, and exposure scenarios.

Assessment of early harvest in the prevention of aflatoxins in peanuts during drought stress conditions

The present study aimed to evaluate the effectiveness of early harvest in preventing aflatoxins in peanuts under drought-stress conditions. A field experiment was conducted on the 2018-2019 and 2019-2020 growing seasons in a greenhouse with an irrigation system to induce three drought stress conditions: no stress, mild, and severe stress. In addition, three harvest dates were proposed: two weeks earlier, one week earlier, and ideal harvest time. The mean peanut yield was 2634 kg/ha, considering the two growing seasons, and the drought stress conditions and harvest dates did not influence significantly. The shelling percentage was significantly higher in samples harvested at ideal harvest (77.7 %) than two weeks earlier (76.2 %) and was not influenced by drought stress conditions. Although a low mean percentage of grains with insect damage was identified, this percentage was statistically higher under severe stress (0.4 %) compared to no-stress conditions (0.2 %). The soil contamination ranged from 2.52 × 103 to 1.64 × 104 CFU/g of Aspergillus section Flavi, and the drought stress resulted in significantly higher concentrations in mild and severe stressed samples. A. section Flavi was found to infect all the peanut kernel samples. The drought stress resulted in higher percentages of A. section Flavi infections in samples from mild and severe stress conditions. The harvest date did not influence the soil and peanut kernel occurrence of A. section Flavi. A total of 435 and 796 strains of A. section Flavi were isolated from soil and peanut kernels, respectively. The potential of aflatoxin production by soil isolates was 31, 44, and 25 % for aflatoxin non-producers, aflatoxin B producers, and aflatoxin B and G producers, respectively, while in peanut kernel isolates were 44, 44, and 12 %. Three different A. section Flavi species were identified from peanut kernels: A. flavus, A. parasiticus, and A. pseudocaelatus. The mean aflatoxin concentration in peanut kernels was 42, 316, and 695.5 μg/kg in samples under no stress, mild stress, and severe stress conditions, respectively. Considering the harvest time, the mean aflatoxin concentration was 9.9, 334.3, and 614.2 μg/kg in samples harvested two weeks earlier, one week earlier, and in ideal harvest, respectively. In conclusion, the early harvest proved to be a viable, cost-free alternative for controlling aflatoxin in the peanut pre-harvest, resulting in a safer product and a better quality for sale and economic gain.

Synthesis, characterization, and reusability of novel nanobiocomposite of endophytic fungus Aspergillus flavus and magnetic nanoparticles (Fe3O4) with dye bioremediation potential

The incorrect disposal of textile dyes, such as Reactive Black 5 (RB5), causes several problems for living beings and the quality of the environment. Nanobiocomposites (NBC) produced from endophytic fungi (potentially remediation dyes-agents) and magnetic nanoparticles have high biotechnological potential due to their superparamagnetic behavior, which would allow their recovery through the magnetic field after the bioremediation process. This work aimed to obtain a new nanobiocomposite from the interaction of magnetite nanoparticles (Fe3O4) with the endophyte Aspergillus flavus (Af-CL-7) to evaluate its bioremediation capacity and to reduce the toxicity of RB5 and its reuse. Before obtaining the NBC, Af-CL-7 showed discoloration of RB5 and it was tolerant to all tested concentrations of this dye. The discovery of the nanobiocomposite textile dye bioremediator product presents a significant environmental advantage by addressing the issue of water pollution caused by textile dyes. The NBC called Af-Fe3O4 was successfully obtained with the magnetized endophyte, and their magnetic properties were verified by VSM analysis and by action of magnetic fields generated by Nd-Fe-B magnets SEM analyzes showed that the nanoparticles did not cause any damage to the hypha morphology, and TEM analyzes confirmed the presence of nanoparticles in the fungus wall and also inside the cell. The NBC Af-Fe3O4 and Af-CL-7 showed, respectively, 96.1% and 92.2% of RB5 discoloration in the first use, 91.1% e 86.2% of discoloration in the validation test, and 89.0% in NBC reuse. In the toxicological bioassay with Lactuca sativa seeds, NBC showed a positive reduction in the toxicity of RB5 after treatment, allowing the hypocotyl growth to be statistically similar to the control with water. Thus, we highlight the promising obtaining process of NBC that could be applied in bioremediation of contaminated waters, wherein the industrial economic cost will depend on the fermentation efficiency, biomass production and nanoparticle synthesis.

Antifungal and elicitor activities of p-hydroxybenzoic acid for the control of aflatoxigenic Aspergillus flavus in kiwifruit

Aspergillus flavus not only reduces kiwifruit production but also synthesizes carcinogenic aflatoxins, resulting in a relevant threat to human health. p-Hydroxybenzoic acid (pHBA) is one of the most abundant phenolics in kiwifruit. In this study, pHBA was found to reduce A. flavus mycelial growth by blocking the fungal mitotic exit network (MEN) and cytokinesis and to inhibit the biosynthesis of aflatoxins B1 and B2. The application of pHBA promoted the accumulation of endogenous pHBA and induced oxidative stress in A. flavus-infected kiwifruit, resulting in an increase in H2O2 content and catalase (CAT) and superoxide dismutase (SOD) activities. Preventive and curative treatments with 5 mM pHBA reduced A. flavus advancement by 46.1% and 68.0%, respectively. Collectively, the antifungal and elicitor properties of pHBA were examined for the first time, revealing new insights into the role of pHBA in the defense response of kiwifruit against A. flavus infection.

Implications of CD45RA and CD45RO T cell subsets in patients of chronic rhinosinusitis with nasal polyposis infected with Aspergillus flavus

T cell subsets (CD4 and CD8) play a prominent role in the development of chronic rhinosinusitis with nasal polyposis (CRSwNP). Colonization with Aspergillus flavus is recognized as a trigger for the growth of nasal polyps. The fungal proteins initiate the recruitment of T cells into the nasal mucosa, which contributes to the progression of nasal polyps. The study included 50 cases of CRSwNP and 50 healthy controls. Biopsies were subjected to KOH and culture for mycological investigation. We examined the changes in T helper (CD4+) and T cytotoxic (CD8+) in total T cells (CD3+) and expression of naive (CD45RA) and memory (CD45RO) cell markers in T cell subsets in peripheral blood mononuclear cells (PBMCs) challenged by A. flavus antigens in cases before and after treatment and in healthy controls by flow cytometry. Predominantly, A. flavus (86%) identified in nasal polyp biopsies of patients. An increased percentage of CD3+CD4+ T cells observed after A. flavus stimulation in patients when compared with healthy controls. The expression of CD4+CD45RA+ cells was significantly (P < .05) reduced in patients and increased CD4+CD45RO+ was observed upon stimulation with A. flavus in patients when compared with healthy control. Continuous exposure to inhaled fungal spores may induce aberrant immune responses to A. flavus spores, causing an allergic immunological reaction with high CD4+T cell responses, resulting in an unfavourable outcome. Elevated CD4+CD45RO+ T cells may transform the pathogenic response and highlight the chances of A. flavus reactive T cells involvement in prompting inflammation in CRSwNP.

Synergistic Effects of Essential Oils and Organic Acids against Aspergillus flavus Contamination in Poultry Feed

Organic acids and essential oils are commonly used in the poultry industry as antimicrobials and for their beneficial effects on gut health, growth performance, and meat quality. A common postharvest storage fungal colonist, Aspergillus flavus, contaminates corn, the primary component of poultry feed, with the highly detrimental mycotoxin, aflatoxin. Aflatoxin adversely affects poultry feed intake, feed conversion efficiency, weight gain, egg production, fertility, hatchability, and poultry meat yield. Both organic acids and essential oils have been reported to inhibit the growth of A. flavus. Thus, we evaluated if the inhibitory synergy between combined essential oils (cinnamon, lemongrass, and oregano) and organic acids (acetic, butyric, and propionic) prevents A. flavus growth. The study confirmed that these compounds inhibit the growth of A. flavus and that synergistic interactions do occur between some of them. Overall, cinnamon oil was shown to have the highest synergy with all the organic acids tested, requiring 1000 µL/L air of cinnamon oil and 888 mg/kg of butyric acid to fully suppress A. flavus growth on corn kernels. With the strong synergism demonstrated, combining certain essential oils and organic acids offers a potentially effective natural method for controlling postharvest aflatoxin contamination in poultry feed.

L-Cysteine hydrochloride inhibits Aspergillus flavus growth and AFB1 synthesis by disrupting cell structure and antioxidant system balance

Aflatoxin B1 (AFB1) is the most potent known naturally occurring carcinogen and pose an immense threat to food safety and human health. L-Cysteine hydrochloride (L-CH) is a food additive often used as a fruit and vegetable preservative and also to approved bread consistency. In this study, we investigated the effects and mechanisms of L-CH as an antimicrobial on the growth of Aspergillus flavus (A. flavus) and AFB1 biosynthesis. L-CH significantly inhibited A. flavus mycelial growth, affected mycelial morphology and AFB1 synthesis. Furthermore, L-CH induced glutathione (GSH) synthesis which scavenged intracellular reactive oxygen species (ROS). RNA-Seq indicated that L-CH inhibited hyphal branching, and spore and sclerotia formation by controlling cell wall and spore development-related genes. Activation of the GSH metabolic pathway eliminated intracellular ROS, leading to hyphal dwarfing. L-CH treatment downregulated most of the Aflatoxin (AF) cluster genes and aflS, aflR, AFLA_091090 transcription factors. This study provides new insights into the molecular mechanism of L-CH control of A. flavus and AFB1 foundation. We believe that L-CH could be used as a food additive to control AFB1 in foods and also in the environment.

Aspergillus spp. renal arteritis after kidney transplantation: A reappraisal

BACKGROUND

Aspergillus spp. is an uncommon and life-threatening cause of transplantrenal artery pseudoaneurysm after kidney transplantation.

CASE

We report the case of a 62-year-old woman who underwent kidney transplantation 10 months before and presented a 7-cm asymptomatic transplant renal artery pseudoaneurysm. Transplanted kidney and pseudoaneurysm were surgically removed in emergency. Renal graft, urine, and pseudoaneurysm cultures grew Aspergillus flavus. She recovered after 12 months of antifungal therapy.

LITERATURE REVIEW

To date 14 cases of Aspergillus spp. renal arteritis after kidney transplantation have been published, including 50% Aspergillus flavus arteritis. Vast majority were diagnosed within 90 days after transplantation (73%). Despite allograft nephrectomy and antifungal therapy, mortality rate was high (33%).

Peppermint essential oil and its nano-emulsion: Potential against aflatoxigenic fungus Aspergillus flavus in food and feed

A facultative parasite called Aspergillus flavus contaminates several important food crops before and after harvest. In addition, the pathogen that causes aspergillosis infections in humans and animals is opportunistic. Aflatoxin, a secondary metabolite produced by Aspergillus flavus, is also carcinogenic and mutagenic, endangering human and animal health and affecting global food security. Peppermint essential oils and plant-derived natural products have recently shown promise in combating A. flavus infestations and aflatoxin contamination. This review discusses the antifungal and anti-aflatoxigenic properties of peppermint essential oils. It then discusses how peppermint essential oils affect the growth of A. flavus and the biosynthesis of aflatoxins. Several cause physical, chemical, or biochemical changes to the cell wall, cell membrane, mitochondria, and associated metabolic enzymes and genes. Finally, the prospects for using peppermint essential oils and natural plant-derived chemicals to develop novel antifungal agents and protect foods are highlighted. In addition to reducing the risk of aspergillosis infection, this review highlights the significant potential of plant-derived natural products and peppermint essential oils to protect food and feed from aflatoxin contamination and A. flavus infestation.

Antifungal activity of Lysinibacillus macroides against toxigenic Aspergillus flavus and Fusarium proliferatum and analysis of its mycotoxin minimization potential

BACKGROUND

Toxigenic fungi (Aspergillus and Fusarium) and their metabolites represent the major cause of corn and corn-based products contamination and consequently lead to severe economic and health issues.

AIM

Our current study aimed to investigate the efficacy of using L. macroides Bac6 as a biological control agent against the toxigenic fungi; A. flavus f10 and F. proliferatum f30 and their mycotoxins.

RESULTS

The results illustrated that A. flavus f10 produced the aflatoxins AFB1 and AFG2 with concentrations of 21.239 and 13.593 ppb, respectively. While F. proliferatum f30 produced fumonisin B1 (9600 ppb). Furthermore, L. macroides showed a high potential for inhibition of toxigenic fungal growth using a dual culture method. F. proliferatum f30 and A. flavus f10 were found to be inhibited by a percentage of 80 and 62.5%, respectively. The results were confirmed using the scanning electron microscope. The antagonistic bacteria, L. macroides, showed chitinase productivity and activity of 26.45 U/L and 0.12 U/mL/min, respectively, which illustrates its potential application as a biocontrol agent. The GC-MS analysis revealed an abundance of Pyrrolo[1,2-a] pyrazine-1,4-dione, Hexahydro in the bacterial supernatant that exhibited antifungal characteristics. L. macroides had a significant reduction of AFB1 and AFG2 produced by A. flavus f10, recording 99.25% and 99% inhibition, respectively. It also showed strong inhibition of fumonisin B1 (90% inhibition) produced by F. proliferatum f30.

CONCLUSION

Thus, the current study is a prospective study evaluating for the first time the potential impact of L. macroides Bac6 against the toxigenic fungi and their toxins.

Antifungal and Antiaflatoxigenic Activities of Massoia Essential Oil and C10 Massoia Lactone against Aflatoxin-Producing Aspergillus flavus

Fungal infection and mycotoxin contamination are major hazards to the safe storage and distribution of foods and feeds consumed by humans and livestock. This study investigated the antifungal and antiaflatoxigenic activities of massoia essential oil (MEO) and its major constituent, C10 massoia lactone (C10), against aflatoxin B (AFB)-producing Aspergillus flavus ATCC 22546. Their antifungal activities were evaluated using a disc diffusion assay, agar dilution method, and a mycelial growth inhibition assay with the AFB analysis using liquid chromatography triple quadrupole mass spectrometry. MEO and C10 exhibited similar antifungal and antiaflatoxigenic activities against A. flavus. C10 was a primary constituent in MEO and represented up to 45.1% of total peak areas analyzed by gas chromatography-mass spectrometry, indicating that C10 is a major compound contributing to the antifungal and antiaflatoxigenic activities of MEO. Interestingly, these two materials increased AFB production in A. flavus by upregulating the expression of most genes related to AFB biosynthesis by 3- to 60-fold. Overall, MEO and C10 could be suitable candidates as natural preservatives to control fungal infection and mycotoxin contamination in foods and feeds as Generally Recognized As Safe (GRAS) in the Flavor and Extract Manufacturers Association of the United States (FEMA), and MEO is a more suitable substance than C10 because of its wider range of uses and higher allowed concentration than C10.

Ar-turmerone suppresses Aspergillus flavus growth and aflatoxin accumulation: Finding a new antifungal agent based on stored maize

Aspergillus flavus (A. flavus) is a common saprophytic pathogenic fungus that produces toxic and carcinogenic aflatoxins prone to contaminate food. Here, we optimized the synthesis method of Ar-turmerone, the main active ingredient in turmeric essential oil, improved its yield and reduced the operation requirements. Moreover, 50.0 μg/mL Ar-turmerone 100.0 % inhibited the colonies growth, spore germination, mycelium biomass and aflatoxin accumulation in 7 days. 2,018 differentially expressed genes (DEGs) such as catA, ppoC, erg7, erg6 and aflO related to the A. flavus growth and aflatoxin product were significantly downregulated including 45 DEGs were 100.0 % suppressed. Besides, Ar-turmerone greatly reduced A. flavus in maize, the optimal storage conditions for maize to avoid A. flavus contamination were determined as 0.940 aw, 400.0 μg/mL Ar-turmerone, and 16.0 °C. Satisfactory odor, luster, taste, and mildew in maize observed after three weeks of storage under the optimal conditions. Thus, Ar-turmerone can be used as a potential food antifungal agent against A. flavus growth and aflatoxin accumulation during food storage.

Infection due to Aspergillus flavus and Rhizopus oryzae complex in a patient with diabetes mellitus

Fungal sinusitis is a pathology that can occur in patients with diabetes mellitus and be associated with a hyperglycemic crisis. It is an aggressive entity with local complications that include involvement of the orbit or the central nervous system, and vascular involvement. Despite surgical and antifungal treatment, mortality raises up to 75%. We report the case of a female patient with a diagnosis of diabetic ketoacidosis and signs of unilateral ophthalmoplegia, which led to the study with magnetic resonance imaging of the central nervous system, finding signs of sinusitis, meningitis, and cerebritis. Initial microbiological studies were negative, and biomarkers such as serum galactomannan and Cryptococcus antigen were also negative. After surgical management and the identification of Aspergillus flavus and Rhizopus spp. in sinus tissue, the patient received treatment with posaconazole and after two months of follow-up she presented clinical improvement. Dual fungal infection and infection by A. flavus are uncommon and clinically relevant entities, with no cases previously reported in our country, therefore this corresponds to a case of clinical interest.

Virulence capacity of different Aspergillus species from invasive pulmonary aspergillosis

Introduction

The opportunistic filamentous fungus Aspergillus causes invasive pulmonary aspergillosis (IPA) that often turns into a fatal infection in immunocompromised hosts. However, the virulence capacity of different Aspergillus species and host inflammation induced by different species in IPA are not well understood.

Methods

In the present study, host inflammation, antimicrobial susceptibilities and virulence were compared among clinical Aspergillus strains isolated from IPA patients.

Results

A total of 46 strains were isolated from 45 patients with the invasive infection, of which 35 patients were diagnosed as IPA. Aspergillus flavus was the dominant etiological agent appearing in 25 cases (54.3%). We found that the CRP level and leukocyte counts (elevated neutrophilic granulocytes and monocytes, and reduced lymphocytes) were significantly different in IPA patients when compared with healthy individuals (P &lt; 0.05). Antifungal susceptibilities of these Aspergillus isolates from IPA showed that 91%, 31%, 14%, and 14% were resistant to Fluconazole, Micafungin, Amphotericin B and Terbinafine, respectively. The survival rate of larvae infected by A. flavus was lower than larvae infected by A. niger or A. fumigatus (P &lt; 0.05).

Discussion

Aspergillus flavus was the dominant clinical etiological agent. Given the prevalence of A. flavus in our local clinical settings, we may face greater challenges when treating IPA patients.

The Effect of Environmental Factors on Mould Counts and AFB1 Toxin Production by Aspergillus flavus in Maize

The toxins produced by Aspergillus flavus can significantly inhibit the use of maize. As a result of climate change, toxin production is a problem not only in tropical and subtropical areas but in an increasing number of European countries, including Hungary. The effect of meteorological factors and irrigation on mould colonization and aflatoxin B1 (AFB1) mycotoxin production by A. flavus were investigated in natural conditions, as well as the inoculation with a toxigenic isolate in a complex field experiment for three years. As a result of irrigation, the occurrence of fungi increased, and toxin production decreased. The mould count of fungi and toxin accumulation showed differences during the examined growing seasons. The highest AFB1 content was found in 2021. The main environmental factors in predicting mould count were temperature (Tavg, Tmax ≥ 30 °C, Tmax ≥ 32 °C, Tmax ≥ 35 °C) and atmospheric drought (RHmin ≤ 40%). Toxin production was determined by extremely high daily maximum temperatures (Tmax ≥ 35 °C). At natural contamination, the effect of Tmax ≥ 35 °C on AFB1 was maximal (r = 0.560–0.569) in the R4 stage. In the case of artificial inoculation, correlations with environmental factors were stronger (r = 0.665–0.834) during the R2–R6 stages.