Search Results (4,293)

This study aimed to model the effects of a_w, pH, and OA, a compound commonly used as a plant elicitor, on the growth and mycotoxin production of Aspergillus welwitschiae and Aspergillus flavus on a fig-based model substrate. Using RSM with a BBD, the combined impact of a_w (0.92–0.99), pH (5.6–6.3), and OA (1–2 mM) on growth and mycotoxin production was evaluated under fixed temperature cycle simulating field conditions. HPLC-FLD quantified OTA and AFs. The results revealed that a_w was the most influential factor governing fungal behaviour. The driest a_w (0.92) significantly delayed growth and completely inhibited the production of OTA and AFB₁. Conversely, high a_w (0.99) was a prerequisite for significant mycotoxin accumulation. While OA at the tested elicitor concentrations did not prove to be a potent independent inhibitor of mycotoxins, its interactions with aw and pH did significantly delay fungal growth. The high R² values (>96%) for growth models indicated a strong goodness-of-fit for comparing the relative impact of the factors. The models for mycotoxins had more moderate R² values, a common finding reflecting the complexity of secondary metabolism. Consequently, these models should be regarded as semi-quantitative tools for identifying high-risk trends rather than for precise prediction. Following internal validation, all developed models proved to be valuable semi-quantitative tools for identifying high-risk conditions, including those with more modest R² values like the OTA model (R² = 56.5%, validation R > 0.945). Full article

The cell wall integrity pathway is activated in response to cell wall stress (CWS). The defense system in aspergilli employs three transcription factors—RlmA, MsnA, and CrzA—which also facilitate adaptation to various abiotic stressors and involve alterations in cytosolic osmolyte composition and membrane lipid profiles. However, their role in adaptation to CWS remains unclear. In Aspergillus niger, CWS induced by Congo red and calcofluor white caused a pronounced cessation of apical growth, accompanied by hyphal globular swelling and an increase in chitin and glucan content in the cell wall. Regarding the osmolyte composition, which predominantly consists of low levels of glycerol and mannitol, glycerol levels were reduced under CWS. Neither the composition nor the amounts of membrane and storage lipids changed following CWS; however, the degree of unsaturation of phospholipids increased due to a higher proportion of linolenic acid, potentially enhancing membrane fluidity. These minor rearrangements of membrane lipids and osmolytes do not confirm their involvement in the adaptation to CWS induced by Congo red and calcofluor white, contrary to previous assumptions based on studies of cell wall integrity pathways. Full article

Aspergillus flavus is both an agricultural and clinical pathogen, notable for its ability to contaminate crops with aflatoxins and cause invasive aspergillosis. The increasing emergence of azole resistance in A. flavus poses a serious challenge to food safety and human health. Although mutations in ergosterol biosynthesis genes have been reported in resistant isolates, their functional contributions remain largely unvalidated. In this study, we investigated the role of the CYP51A Y119F mutation in azole resistance. Site-directed mutants were generated using PCR-based gene editing, and their susceptibility to antifungal agents was assessed through Clinical and Laboratory Standards Institute broth microdilution and agar diffusion assays. The Y119F mutation reduced susceptibility specifically to voriconazole and isavuconazole, while susceptibility to itraconazole and posaconazole remained unchanged. To explore the structural basis of this phenotype, molecular dynamics simulations were performed. The mutant protein exhibited greater fluctuations and reduced conformational stability compared to the wild-type enzyme. Tunnel analysis further indicated that the Y119F substitution caused narrowing and shortening of the main access tunnels to the heme-binding pocket, likely impairing azole access and binding. The combined biochemical and structural analyses suggest that Y119F represents a primary resistance-conferring mutation that modifies the structural dynamics of CYP51A. Full article

Itaconic acid (IA), one of the top twelve renewable platform chemicals, is a key precursor for polymer synthesis. Here, we engineered Myceliophthora thermophila for efficient consolidated biocatalytic IA production from lignocellulose by introducing the heterologous IA pathway (cis-aconitic acid decarboxylase (CAD), mitochondrial tricarboxylic transporter (MTT), major facilitator superfamily transporter (MFS) from Aspergillus terreus), and boosting CAD expression and precursor supply. A critical issue was temperature mismatch: optimal fungal growth vs. CAD activity. Transcriptomics analysis identified reduced expression of glycolytic rate-limiting enzymes (fructose-bisphosphate aldolase, FBA; phosphofructokinase, PFK) at 40 °C. Overexpressing these enzymes in strain IA32 generated strain IA41 (with 3.1-fold and 2.8-fold higher expression of pfk and fba, respectively), which accelerated glucose consumption by 53.2% and increased IA yield by 55.1% A two-stage temperature-shift strategy (45 °C for growth/saccharification, 40 °C for CAD activity) was developed. The engineered strain achieved 3.93 g/L IA in shake flasks and 10.51 g/L in corncob fed-batch fermentation—the highest reported titer for consolidated lignocellulose-to-IA processes. This establishes M. thermophila as a robust platform for cost-effective IA production from lignocellulose. Full article

Background: Ozonation is a non-thermal process that can remodel the chemistry and bioactivity of plant extracts. We evaluated whether ozonating green tea extract enhances its phenolic composition and in vitro bioactivity in relation to nutrition and food applications, with potential clinical applications. Methods: Ethanolic green tea extract (GTE) was exposed to ozone (0–7 L/min, 5 h) to yield an ozonated extract (GTOE). Phenolics were quantified by the HPLC. Bioactivities included antimicrobial testing (agar diffusion; MIC/MBC/MFC), antibiofilm formation, time-kill kinetics (0–180 min), bacteria-induced hemolysis in human RBCs, DPPH radical scavenging, pancreatic lipase inhibition, and scratch-wound closure in human fibroblasts. Data from n = 3 independent experiments were analyzed by one-way ANOVA with Tukey’s post hoc test (α = 0.05). Results: Ozonation increased gallic acid (3150.92 to 3229.69 µg/g) and ellagic acid (2470.66 to 2789.40 µg/g), while catechin decreased slightly (2634.09 to 2535.09 µg/g). Compared with GTE, GTOE produced larger inhibition zones and lower MIC/MBC/MFC against Candida albicans, Bacillus subtilis, Staphylococcus aureus, Klebsiella pneumoniae, and Salmonella typhi; Aspergillus niger remained unsusceptible. For example, inhibition zones for S. aureus and K. pneumoniae increased by 2–4 mm and MIC/MBC values were 2-8-fold lower. Candida albicans showed marked sensitivity (MFC 500 to 125 µg/mL). GTOE exhibited superior, dose-dependent antibiofilm activity across all tested strains, reaching up to 97.82% inhibition, (highest for S. aureus and S. typhi, at 75% MBC). GTOE reduced bacterial counts more rapidly than GTE across all tested strains, achieving full eradication within 150 min. Bacteria-induced hemolysis was inhibited by 97% at 75% MIC with GTOE, versus 93–96% with GTE. Antioxidant capacity improved (DPPH IC₅₀ 3.31 vs. 5.54 μg/mL), as did lipase inhibition IC₅₀ 6.06 vs. 17.69 μg/mL). Wound closure at 48 h increased (GTOE 61.1%; GTE 56.8%; control 50.8%). Conclusions: Controlled ozonation of green tea extract remodeled phenolics and consistently enhanced antimicrobial, antibiofilm, antioxidant, potential anti-obesity, and wound-healing activities in vitro. These results support food-grade optimization and safety/by-product profiling, followed by in vivo validation at diet-relevant doses, to enable nutrition, food, and potential clinical applications. Full article

Two new chromone derivatives, cnidimols I and J (1 and 2), together with ten known aromatic derivatives (3–12), were isolated from the Beibu Gulf algicolous fungus Aspergillus versicolor GXIMD 02518. Their structures were determined by comprehensive physicochemical and spectroscopic data interpretation. The absolute configurations of 1 and 2 were accomplished by ECD calculations and X-ray diffraction analysis. Compound 1 was obtained as a pair of enantiomers, which were separated by chiral-phase HPLC analysis. Notably, 3,7-dihydroxy-1,9-dimethyldibenzofuran (6) displayed significant inhibition in LPS-induced NF-κB luciferase activity in RAW 264.7 macrophages, which further inhibited RANKL-induced osteoclast differentiation without cytotoxicity in bone marrow macrophage cells. Full article

Chitin is an essential polysaccharide of the fungal cell wall, critical for structural integrity, cell division and, in pathogenic fungi, virulence. As chitin is absent in both plant and mammalian systems, chitin synthases are considered attractive targets for the specific control of fungal pathogens. Yet despite decades of research, structural information on chitin synthases was lacking and inhibitors have failed to gain approval in the clinic. Current inhibitors are also ineffective against major agricultural pathogens such as Aspergillus and Fusarium species, largely due to the presence of multiple chitin synthase isoforms in filamentous fungi and the cell wall compensatory response induced under stress. However, recent cryo-electron microscopy structures of Class I chitin synthases from yeasts Saccharomyces cerevisiae and Candida albicans and an oomycete chitin synthase have provided unprecedented insights into the structural and mechanistic properties of these large, transmembrane proteins. These studies revealed conserved, domain-swapped homodimer architectures, distinct substrate binding and catalytic pockets, and sophisticated intrinsic regulatory mechanisms. With these breakthroughs, this review summarises our current understanding of fungal chitin biosynthesis, the challenges that remain to fully biochemically characterise these enzymes, and considers how the new structural insights may guide the development of broad-spectrum antifungals. Full article

Food matrices such as phytic acid, starch, and proteins can chelate heavy metals, acting as stabilizers that significantly hinder accurately detecting heavy metal contamination. This study proposes a biological digestion strategy to overcome such interference. The gene sequences for phytase (appA) from Escherichia coli (E. coli), α-amylase (amyA) from Escherichia coli (E. coli), and protease (AO090120000474) from Aspergillus oryzae were identified via bioinformatics screening. Whole-cell biosensors were then developed to simultaneously detect mercury ions (Hg²⁺) and digest phytate, starch, and proteins. In the presence of 100 μM Hg²⁺, biosensor responses improved by 1.43-, 1.38-, and 1.11-fold, respectively. A “heavy metal pollutant bio-digestion pathway” was constructed by integrating genes for synthesizing phytic acid, starch, and protein with those for Hg²⁺ detection. In the presence of 100 μM Hg²⁺, the detection effect was improved by 1.36-fold. The detection limit of the BαAP whole-cell biosensor was 0.082 μM, while the limit of quantitation was 0.272 μM. The study effectively addresses the limitations of biosensor performance in real sample detection. Full article

Betalains are nitrogen-containing pigments found only in Caryophyllales plants and a few Basidiomycetes; no Ascomycota species have been found to contain them. Here, global untargeted metabolomics analysis revealed that the violet pigment generated by the ascomycete Aspergillus sydowii H-1 under standard conditions of cultivation contains six distinct betalains compounds. Genetic analysis revealed tyrosinase (AsTYRs) and DOPA 4,5-dioxygenase (AsDODA1) as key enzymes essential for the synthesis of both the violet pigment and betalains. In addition, AsTYRs and AsDODA1 were found to regulate hyphal development and branching, mycelial pellet compactness, redox homeostasis, and stress responses, all of which had a significant impact on A. sydowii H-1 secondary metabolism. Crucially, two MYB transcription factors, AsMYB1 and AsMYB3, were identified to be negative regulators of violet pigment synthesis. Deletion of AsMYB1 or AsMYB3 boosted pigment yield by 6.7 and 7.3 times, respectively, and increased betalain accumulation, whereas overexpressing them completely eliminated pigment production. Yeast one-hybrid assays and luciferase reporter assays revealed AsMYB1 and AsMYB3 directly bind to the promoters of AsTYR1 and AsTYR2 to suppress the synthesis of betalains and the violet pigment. Our study reported the first betalain-producing ascomycete species and elucidated the molecular basis of its pigment regulation, providing valuable insights for the microbial synthesis of natural colorants. Full article

Soil-borne plant pathogens pose a serious threat to global food security by causing extensive yield losses and compromising crop quality. Conventional chemical-based control methods often prove inadequate, environmentally harmful, and disruptive to beneficial soil microbiota, highlighting the urgent need for sustainable alternatives. Plant growth-promoting fungi (PGPF) have emerged as effective biocontrol agents capable of suppressing diverse soil-borne pathogens while simultaneously enhancing plant growth and resilience. This review synthesizes current knowledge on the tripartite interactions among plants, pathogens, and PGPF within the rhizosphere, with emphasis on their roles in disease suppression, rhizosphere competence, and plant health promotion. The findings highlight that PGPF such as Trichoderma, Penicillium, Aspergillus, non-pathogenic Fusarium, hypovirulent binucleate Rhizoctonia and sterile fungi can significantly reduce diseases caused by fungi, oomycetes, bacteria, nematodes, and protists through mechanisms including antibiosis, hyperparasitism, competition, and induction of systemic resistance. Evidence also indicates that consortium approaches and bioformulations enhance field efficacy compared to single-strain applications. Despite this progress, challenges such as variability in field performance, limited shelf life of inoculants, and gaps in understanding ecological interactions constrain large-scale use. Overall, the review underscores that PGPF-based strategies represent a promising and sustainable alternative to chemical pesticides, with strong potential for integration into holistic crop disease management under changing climatic conditions. Full article

This study examined the effects of dielectric barrier discharge (DBD) plasma and copper oxide nanoparticles (CuO NPs) on rice seed quality, seedling growth, and fungal inhibition. Sanpatong 1 rice seeds were treated with DBD plasma at three exposure durations (0.4, 0.6, and 0.8 s/cm) and coated with CuO NP solutions at five concentrations (0, 0.02, 0.04, 0.06, and 0.08 M). The experiment followed a split-split-plot design within a randomized complete block design (RCBD), with storage time (0, 2, 4, and 6 months) as the main plot factor. Plasma etching improved seed surface wettability, while CuO NPs increased copper uptake and promoted growth at 0.04–0.06 M but caused toxicity at 0.08 M. Combined treatments suppressed Rhizopus sp. and Rhizoctonia solani, though Aspergillus spp. were less affected. Seed quality declined after six months of storage, likely due to oxidative stress. The best results were obtained with 0.6 s/cm plasma and 0.06 M CuO NPs, maximizing germination, vigor, and seedling growth without toxicity, demonstrating their potential as practical tools for improving rice seed quality and pathogen management. Full article

Almonds are an essential crop for the economy of California. However, mold and mycotoxin contamination of this commodity has a serious impact on food safety and international trade. The contamination levels of molds and the aflatoxigenic potential of Aspergillus section Flavi isolates were studied on almonds collected at a processing plant in California. The mean total fungal count for 80 samples was 1.0 × 10⁴ CFU/g, while 62 samples (77.5%) had a total mold count less than 1.0 × 10⁴ CFU/g. The most common fungal contaminants were Aspergillus section Nigri (100% of samples), followed by Penicillium (57.5%) and Cladosporium (52.5%) species. Rhizopus, Fusarium and Alternaria spp. were less frequent. A total of 26 A. section Flavi strains were identified, with most strains (23) belonging to the L morphotype of A. flavus. In addition, two S morphotypes of A. flavus, and one A. tamarii strain were observed. Other Aspergillus species, including A. terreus and A. ochraceus were rare. High Performance Liquid Chromatography (HPLC) analysis revealed that 9 out of 13 isolated A. flavus strains produced aflatoxin B₁ (AFB₁) on yeast extract sucrose media. The highest levels of AFB₁ were produced by two A. flavus isolates belonging to the S morphotype (78 and 260 µg/kg). Increasing temperatures and drought conditions may change the population dynamics of toxigenic mold strains on almonds, emphasizing the need to continue monitoring these fungal populations. Full article

Aspergillus species are major opportunistic pathogens responsible for invasive aspergillosis, with antifungal resistance posing increasing challenges to their treatment worldwide. We investigated the antifungal susceptibility and genomic features of Aspergillus isolates from sterile clinical specimens collected at a tertiary hospital in Thailand between January and December 2023. In total, 24 isolates were identified via culture and tested for amphotericin B and voriconazole susceptibility using CLSI M38 broth microdilution, and whole-genome sequencing was performed on selected isolates to characterize resistance mechanisms. Aspergillus fumigatus was the most frequent species (54%), followed by A. flavus (29%) and other less common species. Voriconazole exhibited potent activity against most isolates, although two A. fumigatus strains showed elevated MICs (2–4 µg/mL), meeting resistance thresholds. One isolate (CUAFU23) was confirmed to harbor the cyp51A TR34/L98H mutation, marking the first identification of this canonical azole resistance mechanism in a clinical specimen from Thailand and supporting earlier environmental findings of azole-resistant A. fumigatus carrying the same allele. Genomic profiling of CUAFU23 further revealed subtle but distinct shifts in domain composition compared with susceptible strains, suggesting broader adaptive changes. The above findings underscore the emergence of azole-resistant A. fumigatus in Thailand and highlight the importance of ongoing surveillance using combined phenotypic and molecular approaches. Full article

Essential oils (EOs) from oregano (Origanum vulgare), rosemary (Salvia rosmarinus), clove (Syzygium aromaticum), thyme (Thymus vulgaris), cinnamon (Cinnamomum verum), and basil (Ocimum basilicum) possess antifungal properties. This study aimed to evaluate their ability to inhibit the growth of fungi isolated from the rot of banana peel (Musa paradisiaca) to control or reduce fungal growth in bananas. The methodology involved preparing dilutions of EOs and inoculating them onto Potato Dextrose Agar (PDA) medium amended with chloramphenicol to prevent bacterial contamination. Fungal species, including Trichoderma spp., Aspergillus spp., Penicillium spp., and Fusarium spp., were isolated, purified, and characterized macroscopically and microscopically. Their growth was assessed ex vivo and the inhibition percentage was measured in vitro. The ex vivo analysis revealed that the severity of fungal infection, ranked from highest to lowest, was as follows: Penicillium spp., Trichoderma spp., Fusarium spp., and Aspergillus spp. The results showed that rosemary and basil oils did not inhibit fungal growth, whereas clove oil, cinnamon, and oregano were effective against the four tested fungi at 800, 400, and 200 ppm, respectively. These findings suggest that certain EOs, including clove, cinnamon, and oregano, have strong antifungal potential and could serve as eco-friendly alternatives to synthetic fungicides in banana postharvest disease management. Full article

This study assessed mycotoxin contamination in roasted peanut snacks and kluiklui (fried pressed peanut cake), and consumer exposure in southern Benin. Roasted peanut snacks and kluiklui were sampled from markets across six municipalities, and their production follow-up was conducted on two sites using different processing methods. Mycotoxins were quantified using UPLC-MS/MS, while fungal species were identified via culture-based methods. Exposure to aflatoxin B1, total aflatoxins and ochratoxin A was estimated. Aflatoxin B1 predominated, reaching 169 µg/kg in roasted peanut snacks and 2144.64 µg/kg in marketed kluiklui. In contrast, just-produced kluiklui contained much lower levels (11.73–37.78 µg/kg). Aspergillus flavus and Aspergillus niger predominated in kluiklui from the first processing site, while Aspergillus chevalieri dominated in kluiklui from the second processing site. The grinding step (using public grinder) was identified as the main contamination point. The significative higher mycotoxin levels in kluiklui sampled on markets compared to just-produced kluiklui are probably due to poor storage conditions. Dietary exposure estimates revealed that margins of exposure for aflatoxins were far below the safety threshold of 10,000, and liver cancer risk estimates were particularly high for kluiklui consumers. Kluiklui consumption poses a significant health risk in Benin. Improved hygiene in public grinders and better storage practices are urgently needed to reduce contamination and protect consumers’ health. Full article