RESUMEN
Aflatoxins are the most dangerous mycotoxins for food safety. They are mainly produced by Aspergillus flavus, A. parasiticus, and A. minisclerotigenes. The latter, an understudied species, was the main culprit for outbreaks of fatal aflatoxicosis in Kenya in the past. To determine specific genetic characteristics of these Aspergillus species, their genomes are comparatively analyzed. Differences reflecting the typical habitat are reported, such as an increased number of carbohydrate-active enzymes, including enzymes for lignin degradation, in the genomes of A. minisclerotigenes and A. parasiticus. Further, variations within the aflatoxin gene clusters are described, which are related to different chemotypes of aflatoxin biosynthesis. These include a substitution within the aflL gene of the A. parasiticus isolate, which leads to the translation of a stop codon, thereby switching off the production of the group 1 aflatoxins B1 and G1. In addition, we demonstrate that the inability of the A. minisclerotigenes isolates to produce group G aflatoxins is associated with a 2.2 kb deletion within the aflF and aflU genes. These findings reveal a relatively high genetic homology among the three Aspergillus species investigated. However, they also demonstrate consequential genetic differences that have an important impact on risk-assessment and food safety.
Asunto(s)
Aflatoxinas , Aspergillus , Aflatoxinas/biosíntesis , Aflatoxinas/genética , Aflatoxinas/metabolismo , Aspergillus/genética , Aspergillus/metabolismo , Aspergillus flavus/genética , Aspergillus flavus/metabolismo , Genoma Fúngico , Ecosistema , Familia de Multigenes , Filogenia , Especificidad de la EspecieRESUMEN
Food crops around the world are commonly contaminated with Aspergillus flavus, which can produce the carcinogenic mycotoxin aflatoxin B1 (AFB1). The objective of this study is to test an X-ray irradiation sterilization method for studying AFB1 in contaminated maize samples in the laboratory. Maize that had been naturally contaminated with 300 ppb AFB1 by the growth of aflatoxigenic A. flavus was ground and then irradiated at 0.0, 1.0, 1.5, 2.0, 2.5, and 3.0 kGy. A. flavus was quantified by dilution plating on potato dextrose agar (PDA) and modified Rose Bengal media (MDRB) for viability and qPCR for gene presence. AFB1 was quantified by HPLC and ELISA. A. flavus viability, but not gene copies, significantly decreased with increasing doses of radiation (PDA: p < 0.001; MDRB: p < 0.001; qPCR: p = 0.026). AFB1 concentration did not significantly change with increasing doses of radiation (HPLC: p = 0.153; ELISA: p = 0.567). Our results imply that X-ray irradiation is an effective means of reducing viable A. flavus without affecting AFB1 concentrations. Reducing the hazard of fungal spores and halting AFB1 production at the targeted dose are important steps to safely and reproducibly move forward research on the global mycotoxin challenge.
Asunto(s)
Aflatoxina B1 , Aspergillus flavus , Zea mays , Zea mays/microbiología , Zea mays/efectos de la radiación , Aflatoxina B1/efectos de la radiación , Aspergillus flavus/efectos de la radiación , Aspergillus flavus/crecimiento & desarrollo , Aspergillus flavus/metabolismo , Aspergillus flavus/efectos de los fármacos , Rayos X , Contaminación de Alimentos/prevención & control , Irradiación de Alimentos/métodos , Viabilidad Microbiana/efectos de la radiación , Viabilidad Microbiana/efectos de los fármacosRESUMEN
Aflatoxins are a group of high toxic mycotoxins in food chain. Recent studies showed that aflatoxins might contaminate post-fermented tea, but the result remains controversial. Here, Aspgergillus flavus growth and aflatoxin production were characterized in Puerh tea, peanut and polished rice at different initial water activity (aw) values for long-term storage. As a result, food initial aw value was the critical factor for A. flavus growth and aflatoxin production, and A. flavus almost not grew on foods at aw value lower than 0.8. A. flavus grew best in peanut, followed by rice, but growth on Puerh tea was limited. A. flavus growth was inhibited significantly by adding tea to Potato Dextrose Agar (PDA). Accordingly, aflatoxins produced dramatically in peanut, followed by rice at the first 90 days storage. However, aflatoxin neither produced in Puerh tea nor on tea modified PDA, indicating tea components inhibited A. flavus growth and aflatoxins synthesis.
Asunto(s)
Aflatoxinas , Arachis , Aspergillus flavus , Contaminación de Alimentos , Almacenamiento de Alimentos , Oryza , Aspergillus flavus/metabolismo , Aspergillus flavus/crecimiento & desarrollo , Aflatoxinas/análisis , Aflatoxinas/metabolismo , Oryza/química , Oryza/microbiología , Oryza/metabolismo , Arachis/química , Arachis/microbiología , Arachis/crecimiento & desarrollo , Contaminación de Alimentos/análisis , Contaminación de Alimentos/prevención & control , Té/química , Camellia sinensis/química , Camellia sinensis/microbiología , Camellia sinensis/metabolismo , Camellia sinensis/crecimiento & desarrolloRESUMEN
The toxicity of the contaminated powder contributed to toxic aflatoxins has been well-known in the literature. However, before this study, the specific fungal strain behind aflatoxin production remained unidentified. Our research aimed to isolate and identify fungi from the tainted sandwiches while also assessing the preservation of sandwiches in ambient conditions. The study pinpointed Aspergillus flavus as the fungus responsible for aflatoxin production. Analysis revealed that the sandwich samples contaminated with pure A. flavus exhibited a significant Aflatoxin B1 (AFB1) concentration of 55.2 ± 0.21 ng/g, accompanied by a spore count of 2 × 106 Colony-Forming Unit (CFU)/g after ten days. In contrast, sandwich samples contaminated with the unspecified fungi displayed a lower AFB1 content of 16.21 ± 0.42 ng/g, with a spore count of 2.2 × 102 CFU/g after the same duration. In the prevention study, the efficacy of the ethanol spray method for inhibiting aflatoxin from A. flavus was investigated. Results demonstrated that a 70 % ethanol concentration at a ratio of 2.0 % total weight of the sandwich proved highly effective, significantly impeding fungal growth. This method extended the preservation time by sevenfold compared to the control. Importantly, tests at 2.0 % ethanol of the sandwich weight did not detect aflatoxin presence.
Asunto(s)
Aflatoxina B1 , Aflatoxinas , Aspergillus flavus , Contaminación de Alimentos , Microbiología de Alimentos , Aspergillus flavus/metabolismo , Aspergillus flavus/crecimiento & desarrollo , Aflatoxina B1/metabolismo , Aflatoxina B1/análisis , Contaminación de Alimentos/análisis , Aflatoxinas/análisis , Aflatoxinas/metabolismo , Esporas Fúngicas/crecimiento & desarrollo , Etanol/metabolismo , Recuento de Colonia Microbiana , Hongos/metabolismo , Hongos/aislamiento & purificación , Hongos/efectos de los fármacos , Conservación de Alimentos/métodosRESUMEN
The climate-change-coupled fungal burden in crop management and the need to reduce chemical pesticide usage highlight the importance of finding sustainable ways to control Aspergillus flavus. This study examines the effectiveness of 50 Pseudomonas isolates obtained from corn rhizospheres against A. flavus in both solid and liquid co-cultures. The presence and quantity of aflatoxin B1 (AFB1) and AFB1-related compounds were determined using high-performance liquid chromatography-high resolution mass spectrometry analysis. Various enzymatic- or non-enzymatic mechanisms are proposed to interpret the decrease in AFB1 production, accompanied by the accumulation of biosynthetic intermediates (11-hydroxy-O-methylsterigmatocystin, aspertoxin, 11-hydroxyaspertoxin) or degradation products (the compounds C16H10O6, C16H14O5, C18H16O7, and C19H16O8). Our finding implies the upregulation or enhanced activity of fungal oxidoreductases and laccases in response to bacterial bioactive compound(s). Furthermore, non-enzymatic reactions resulted in the formation of additional degradation products due to acid accumulation in the fermented broth. Three isolates completely inhibited AFB1 or any AFB1-related compounds without significantly affecting fungal growth. These bacterial isolates supposedly block the entire pathway for AFB1 production in the fungus during interaction. Apart from identifying effective Pseudomonas isolates as potential biocontrol agents, this work lays the foundation for exploring new bacterial bioactive compounds.
Asunto(s)
Aflatoxina B1 , Aspergillus flavus , Pseudomonas , Zea mays , Aflatoxina B1/metabolismo , Aflatoxina B1/biosíntesis , Pseudomonas/metabolismo , Aspergillus flavus/metabolismo , Aspergillus flavus/crecimiento & desarrollo , Zea mays/microbiología , RizosferaRESUMEN
Application of actinobacteria has grown exponentially in recent years in sustainable agricultural. Most actinobacterial inoculants are tailored to function as either biocontrol agents or biofertilizers. Hence, there is the need to obtain and include multifunctional actinobacterial strains in inocula formulations. In this research, 90 actinobacterial isolates were isolated from rhizospheric and non-rhizospheric soils of Algerian Saharan arid regions and were screened for their activity against the phytopathogenic fungi Alternaria alternata, Aspergillus flavus, Botrytis cinerea, Fusarium oxysporum, and Fusarium solani. Five isolates that inhibited at least three of these fungi were characterized according to morphological, environmental and biochemical parameters, and were preliminarily identified as Streptomyces enissocaesilis A1, Streptomyces olivoverticillatus A5, Streptomyces erumpens A6, Streptomyces cavourensis A8, and Streptomyces microflavus A20. These strains were then screened for plant growth promoting activities. All strains produced siderophores, hydrocyanic acid, ammonia and the auxin indole-3-acetic acid (IAA) and were capable of solubilizing phosphate. The highest producer of siderophores (69.19 percent siderophore units), ammonia (70.56 µg mL-1) and IAA (148.76 µg mL-1) was strain A8, A20, and A5, respectively. These findings showed that the five actinobacteria are multipurpose strains with simultaneous antifungal and plant growth promoting activities and have the potential to be used for sustainable agricultural practices, particularly in arid regions.
Asunto(s)
Actinobacteria , Antifúngicos , Microbiología del Suelo , Antifúngicos/farmacología , Antifúngicos/metabolismo , Actinobacteria/metabolismo , Actinobacteria/clasificación , Actinobacteria/genética , Actinobacteria/aislamiento & purificación , Actinobacteria/crecimiento & desarrollo , Alternaria/efectos de los fármacos , Alternaria/crecimiento & desarrollo , Ácidos Indolacéticos/metabolismo , Sideróforos/metabolismo , Fusarium/efectos de los fármacos , Fusarium/crecimiento & desarrollo , Reguladores del Crecimiento de las Plantas/metabolismo , Reguladores del Crecimiento de las Plantas/farmacología , Streptomyces/clasificación , Streptomyces/aislamiento & purificación , Streptomyces/genética , Streptomyces/metabolismo , Aspergillus flavus/crecimiento & desarrollo , Aspergillus flavus/efectos de los fármacos , Aspergillus flavus/metabolismo , Botrytis/efectos de los fármacos , Botrytis/crecimiento & desarrollo , Filogenia , Argelia , Desarrollo de la Planta , Antibiosis , África del NorteRESUMEN
Aspergillus flavus, the primary mold that causes food spoilage, poses significant health and economic problems worldwide. Eliminating A. flavus growth is essential to ensure the safety of agricultural products, and extracellular compounds (ECCs) produced by Bacillus spp. have been demonstrated to inhibit the growth of this pathogen. In this study, we aimed to identify microorganisms efficient at inhibiting A. flavus growth and degrading aflatoxin B1. We isolated microorganisms from soil samples using a culture medium containing coumarin (CM medium) as the sole carbon source. Of the 498 isolates grown on CM medium, only 132 bacterial strains were capable of inhibiting A. flavus growth. Isolate 3BS12-4, identified as Bacillus siamensis, exhibited the highest antifungal activity with an inhibition ratio of 43.10%, and was therefore selected for further studies. The inhibition of A. flavus by isolate 3BS12-4 was predominantly attributed to ECCs, with a minimum inhibitory concentration and minimum fungicidal concentration of 0.512 g/ml. SEM analysis revealed that the ECCs disrupted the mycelium of A. flavus. The hydrolytic enzyme activity of the ECCs was assessed by protease, ß-1,3-glucanase, and chitinase activity. Our results demonstrate a remarkable 96.11% aflatoxin B1 degradation mediated by ECCs produced by isolate 3BS12-4. Furthermore, treatment with these compounds resulted in a significant 97.93% inhibition of A. flavus growth on peanut seeds. These findings collectively present B. siamensis 3BS12-4 as a promising tool for developing environmentally friendly products to manage aflatoxin-producing fungi and contribute to the enhancement of agricultural product safety and food security.
Asunto(s)
Aflatoxina B1 , Antifúngicos , Aspergillus flavus , Bacillus , Agentes de Control Biológico , Microbiología del Suelo , Aspergillus flavus/efectos de los fármacos , Aspergillus flavus/crecimiento & desarrollo , Aspergillus flavus/metabolismo , Bacillus/metabolismo , Bacillus/efectos de los fármacos , Aflatoxina B1/metabolismo , Aflatoxina B1/biosíntesis , Agentes de Control Biológico/farmacología , Antifúngicos/farmacología , Pruebas de Sensibilidad Microbiana , Medios de Cultivo/química , Micelio/efectos de los fármacos , Micelio/crecimiento & desarrolloRESUMEN
Aspergillus flavus conidia are widespread in air; they attach to food and feed crops and secrete aflatoxins, which results in serious contamination. Germination of A. flavus conidia is the most critical step in contamination of food by A. flavus. This study aims to gain an insight into A. flavus conidia through dormancy to germination to provide a theoretical basis for inhibition of A. flavus conidia germination. The morphological changes and regulation mechanism of A. flavus conidia germination at 0, 4, 8, and 12 hours were observed. Transcriptomic and metabolomic analyses showed that conidia became active from dormancy (0 hour) to the initial stage of germination (4 hours), cellular respiration and energy metabolism increased, and amino acids and lipids were synthesized rapidly. The number of differentially expressed genes and differential metabolites was highest at this stage. Besides, we found that conidia germination had selectivity for different carbon and nitrogen sources. Compared with monosaccharides, disaccharides, as the only carbon source, significantly promoted the germination of conidia. Moreover, MepA, one of genes in the ammonium transporter family was studied. The gene deletion mutant ΔMepA had a significant growth defect, and the expression of MeaA was significantly upregulated in ΔMepA compared with the wild-type, indicating that both MepA and MeaA played an important role in transporting ammonium ions.IMPORTANCEThis is the first study to use combined transcriptomic and metabolomics analyses to explore the biological changes during germination of Aspergillus flavus conidia. The biological process with the highest changes occurred in 0-4 hours at the initial stage of germination. Compared with polysaccharides, monosaccharides significantly increased the size of conidia, while significantly decreasing the germination rate of conidia. Both MeaA and MepA were involved in ammonia transport and metabolism during conidia germination.
Asunto(s)
Aspergillus flavus , Regulación Fúngica de la Expresión Génica , Esporas Fúngicas , Aspergillus flavus/metabolismo , Aspergillus flavus/genética , Aspergillus flavus/crecimiento & desarrollo , Aspergillus flavus/fisiología , Esporas Fúngicas/metabolismo , Esporas Fúngicas/crecimiento & desarrollo , Esporas Fúngicas/genética , Proteínas Fúngicas/metabolismo , Proteínas Fúngicas/genética , Transcriptoma , Nitrógeno/metabolismo , Carbono/metabolismo , Aflatoxinas/metabolismo , Aflatoxinas/genética , Metabolómica , Metabolismo EnergéticoRESUMEN
Introduction. Aspergillus flavus and Fusarium keratoplasticum are common causative pathogens of fungal keratitis (FK), a severe corneal disease associated with significant morbidity and vision loss. Escalating incidence of antifungal resistance to available antifungal drugs poses a major challenge to FK treatment. Cold atmospheric plasma (CAP) is a pioneering nonpharmacologic antimicrobial intervention that has demonstrated potential as a broad-spectrum antifungal treatment.Gap statement. Previous research highlights biofilm-associated resistance as a critical barrier to effective FK treatment. Although CAP has shown promise against various fungal infections, its efficacy against biofilm and conidial forms of FK pathogens remains inadequately explored.Aim. This study aims to investigate the antifungal efficacy of CAP against clinical fungal keratitis isolates of A. flavus and F. keratoplasticum in vitro.Methodology. Power parameters (22-27 kVpp, 300-400 Hz and 20-80 mA) of a dielectric barrier discharge CAP device were optimized for inactivation of A. flavus biofilms. Optimal applied voltage and total current were applied to F. keratoplasticum biofilms and conidial suspensions of A. flavus and F. keratoplasticum. The antifungal effect of CAP treatment was investigated by evaluating fungal viability through means of metabolic activity, c.f.u. enumeration (c.f.u. ml-1) and biofilm formation.Results. For both fungal species, CAP exhibited strong time-dependent inactivation, achieving greater than 80â% reduction in metabolic activity and c.f.u. ml-1 within 300 s or less, and complete inhibition after 600 s of treatment.Conclusion. Our findings indicate that CAP is a promising broad-spectrum antifungal intervention. CAP treatment effectively reduces fungal viability in both biofilm and conidial suspension cultures of A. flavus and F. keratoplasticum, suggesting its potential as an alternative treatment strategy for fungal keratitis.
Asunto(s)
Antifúngicos , Aspergillus flavus , Biopelículas , Fusarium , Queratitis , Gases em Plasma , Esporas Fúngicas , Aspergillus flavus/efectos de los fármacos , Fusarium/efectos de los fármacos , Biopelículas/efectos de los fármacos , Gases em Plasma/farmacología , Esporas Fúngicas/efectos de los fármacos , Antifúngicos/farmacología , Queratitis/microbiología , Infecciones Fúngicas del Ojo/microbiología , Humanos , Fusariosis/microbiología , Viabilidad Microbiana/efectos de los fármacosRESUMEN
BACKGROUND: Pulmonary aspergillosis is a prevalent opportunistic fungal infection that can lead to mortality in pediatric patients with underlying immunosuppression. Appropriate and timely treatment of pulmonary aspergillosis can play a crucial role in reducing mortality among children admitted with suspected infections. CASE PRESENTATION: The present study reports three cases of inappropriate treatment of pulmonary aspergillosis caused by Aspergillus flavus in two Iranian pediatric patients under investigation and one Afghan patient. Unfortunately, two of them died. The cases involved patients aged 9, 1.5, and 3 years. They had been diagnosed with pulmonary disorders, presenting nonspecific clinical signs and radiographic images suggestive of pneumonia. The identification of A. flavus was confirmed through DNA sequencing of the calmodulin (CaM) region. CONCLUSION: A. flavus was the most prevalent cause of pulmonary aspergillosis in pediatric patients. Early diagnosis and accurate antifungal treatment of pulmonary aspergillosis could be crucial in reducing the mortality rate and also have significant potential for preventing other complications among children. Moreover, antifungal prophylaxis seems to be essential for enhancing survival in these patients.
Asunto(s)
Antifúngicos , Aspergillus flavus , Aspergilosis Pulmonar , Humanos , Aspergillus flavus/aislamiento & purificación , Antifúngicos/uso terapéutico , Niño , Masculino , Preescolar , Aspergilosis Pulmonar/tratamiento farmacológico , Aspergilosis Pulmonar/diagnóstico , Lactante , Femenino , Resultado Fatal , IránRESUMEN
Aspergillus species are common hyphal fungi. In addition to allergies and mycotoxicosis, Aspergillus species can cause various infections known as aspergillosis. Aspergillosis of the respiratory tract, central nervous system, skin and soft tissues is well described. However, musculoskeletal infections due to invasive aspergillosis are not well described. Fungal joint infection due to invasive aspergillosis is a rare form of septic arthritis. In this case report, a patient who admitted to our hospital for liver transplantation and developed knee joint arthritis caused by Aspergillus flavus/Aspergillus oryzae during this process was presented. A 28-year-old male patient with autoimmune hepatitis was admitted to hospital with decompensated liver cirrhosis and encephalopathy. The patient, who was awaiting an emergency liver transplant, developed pain, swelling and limitation of movement in his right knee and appropriate consultations and tests were requested. Three joint fluid cultures taken one day apart and nine days later were positive for fungal growth. Macroscopic examination of the mould growth and microscopic examination with lactophenol cotton blue suggested a species belonging to the A.flavus complex and the isolate was identified as A.flavus/A.oryzae by matrix-assisted laser desorption/ionisation mass spectrometry (MALDI-TOF MS) (EXS 2600, Zybio, China). As a result of ITS gene sequencing, the species was determined to be A.oryzae. As cases have been reported where A.flavus and A.oryzae species could not be distinguished by ITS gene sequencing, the pathogen was defined as A.flavus/oryzae. The patient died of liver disease during treatment with amphotericin B. There are few cases of arthritis caused by Aspergillus species in the literature. Aspergillus species found in joint infections are, Aspergillus fumigatus, A.flavus, Aspergillus niger and Aspergillus terreus species complexes, in order of frequency. A.flavus and A.oryzae are closely related. They are difficult to distinguish by conventional methods, MALDI-TOF MS or ITS region sequencing, which is commonly used for genus/species identification in fungi. The number of Aspergillus arthritis cases is low and the identification methods applied to the species reported as causative agents in most studies can identify at the species complex level. In addition, it can be assumed that species not previously reported as causative agents may be encountered as a result of developments in identification methods. In the few publications in the literature where A.flavus complex was reported as the causative agent of joint infections, it seems possible that some of the agents may be A.flavus and some may be A.oryzae, since the agents were identified at the complex level. There are a limited number of cases in the literature where A.oryzae is the causative agent, particularly in the respiratory tract. A PubMed search using the keywords "A.oryzae infections, arthritis, osteomyelitis" did not reveal any literature on joint infections caused by A.oryzae.
Asunto(s)
Artritis Infecciosa , Aspergilosis , Aspergillus flavus , Aspergillus oryzae , Articulación de la Rodilla , Humanos , Masculino , Adulto , Aspergillus flavus/aislamiento & purificación , Aspergilosis/diagnóstico , Aspergilosis/microbiología , Aspergilosis/tratamiento farmacológico , Artritis Infecciosa/microbiología , Artritis Infecciosa/diagnóstico , Artritis Infecciosa/tratamiento farmacológico , Articulación de la Rodilla/microbiología , Aspergillus oryzae/aislamiento & purificación , Turquía , Hepatitis Autoinmune/microbiología , Hepatitis Autoinmune/tratamiento farmacológico , Trasplante de Hígado , Antifúngicos/uso terapéuticoRESUMEN
Aspergillus flavus infects important crops and produces carcinogenic aflatoxins, posing a serious threat to food safety and human health. Biochemical analysis and RNA-seq were performed to investigate the effects and mechanisms of piperitone on A. flavus growth and aflatoxin B1 biosynthesis. Piperitone significantly inhibited the growth of A. flavus, AFB1 production, and its pathogenicity on peanuts and corn flour. Differentially expressed genes (DEGs) associated with the synthesis of chitin, glucan, and ergosterol were markedly down-regulated, and the ergosterol content was reduced, resulting in a disruption in the integrity of the cell wall and cell membrane. Moreover, antioxidant genes were down-regulated, the correspondingly activities of antioxidant enzymes such as catalase, peroxidase, and superoxide dismutase were reduced, and levels of superoxide anion and hydrogen peroxide were increased, leading to a burst of reactive oxygen species (ROS). Accompanied by ROS accumulation, DNA fragmentation and cell autophagy were observed, and 16 aflatoxin cluster genes were down-regulated. Overall, piperitone disrupts the integrity of the cell wall and cell membrane, triggers the accumulation of ROS, causes DNA fragmentation and cell autophagy, ultimately leading to defective growth and impaired AFB1 biosynthesis.
Asunto(s)
Aflatoxina B1 , Antifúngicos , Aspergillus flavus , Especies Reactivas de Oxígeno , Zea mays , Aspergillus flavus/efectos de los fármacos , Aspergillus flavus/genética , Aspergillus flavus/crecimiento & desarrollo , Aspergillus flavus/metabolismo , Zea mays/microbiología , Antifúngicos/farmacología , Especies Reactivas de Oxígeno/metabolismo , Arachis/microbiología , Pared Celular/efectos de los fármacos , Pared Celular/metabolismoRESUMEN
This study systematically analyzed the effect of Aspergillus flavus infection on the maize starch multi-scale structure, physicochemical properties, processing characteristics, and synthesis regulation. A. flavus infection led to a decrease in the content of starch, an increase in the content of reactive oxygen species (ROS) and malondialdehyde (MDA), a significant decrease in the activities of peroxidase (POD) and superoxide dismutase (SOD). In addition, A. flavus infection had a significant destructive effect on the double helix structure, relative crystallinity and lamellar structure of starch, resulting in the reduction of starch viscosity, affecting the viscoelastic properties of starch, and complicating the gel formation process. However, the eugenol treatment group significantly inhibited the growth of A. flavus during maize storage, protecting the multi-scale structure and processing characteristics of maize starch from being damaged. Transcriptome analysis showed that genes involved in carbohydrate synthesis in maize were significantly downregulated and genes involved in energy synthesis were significantly upregulated, indicating that maize converted its energy storage into energy synthesis to fight the invasion of A. flavus. These results of this study enriched the mechanism of quality deterioration during maize storage, and provide theoretical and technical support for the prevention of A. flavus infection during maize storage.
Asunto(s)
Aspergillus flavus , Almidón , Zea mays , Zea mays/química , Zea mays/microbiología , Aspergillus flavus/metabolismo , Almidón/química , Almidón/metabolismo , Almacenamiento de Alimentos , Especies Reactivas de Oxígeno/metabolismo , Viscosidad , Malondialdehído/metabolismo , Superóxido Dismutasa/metabolismoRESUMEN
Aspergillus flavus and its carcinogenic secondary metabolites, aflatoxins, not only cause serious losses in the agricultural economy, but also endanger human health. Rhein, a compound extracted from the Chinese herbal medicine Rheum palmatum L. (Dahuang), exhibits good anti-inflammatory, anti-tumor, and anti-oxidative effects. However, its effect and underlying mechanisms against Aspergillus flavus have not yet been fully illustrated. In this study, we characterized the inhibition effect of rhein on A. flavus mycelial growth, sporulation, and aflatoxin B1 (AFB1) biosynthesis and the potential mechanism using RNA-seq analysis. The results indicate that A. flavus mycelial growth and AFB1 biosynthesis were significantly inhibited by 50 µM rhein, with a 43.83% reduction in colony diameter and 87.2% reduction in AFB1 production. The RNA-seq findings demonstrated that the differentially expressed genes primarily participated in processes such as spore formation and development, the maintenance of cell wall and membrane integrity, management of oxidative stress, the regulation of the citric acid cycle, and the biosynthesis of aflatoxin. Biochemical verification experiments further confirmed that 50 µM rhein effectively disrupted cell wall and membrane integrity and caused mitochondrial dysfunction through disrupting energy metabolism pathways, leading to decreased ATP synthesis and ROS accumulation, resulting in impaired aflatoxin biosynthesis. In addition, a pathogenicity test showed that 50 µM rhein inhibited A. flavus spore growth in peanut and maize seeds by 34.1% and 90.4%, while AFB1 biosynthesis was inhibited by 60.52% and 99.43%, respectively. In conclusion, this research expands the knowledge regarding the antifungal activity of rhein and provides a new strategy to mitigate A. flavus contamination.
Asunto(s)
Aflatoxina B1 , Antraquinonas , Aspergillus flavus , Especies Reactivas de Oxígeno , Aspergillus flavus/efectos de los fármacos , Aspergillus flavus/metabolismo , Aspergillus flavus/crecimiento & desarrollo , Antraquinonas/farmacología , Especies Reactivas de Oxígeno/metabolismo , Aflatoxina B1/biosíntesis , Aflatoxina B1/toxicidad , Metabolismo Energético/efectos de los fármacos , Esporas Fúngicas/efectos de los fármacos , Esporas Fúngicas/crecimiento & desarrollo , Micelio/efectos de los fármacos , Micelio/crecimiento & desarrollo , Antifúngicos/farmacologíaRESUMEN
The target of rapamycin (TOR) signaling pathway is highly conserved and plays a crucial role in diverse biological processes in eukaryotes. Despite its significance, the underlying mechanism of the TOR pathway in Aspergillus flavus remains elusive. In this study, we comprehensively analyzed the TOR signaling pathway in A. flavus by identifying and characterizing nine genes that encode distinct components of this pathway. The FK506-binding protein Fkbp3 and its lysine succinylation are important for aflatoxin production and rapamycin resistance. The TorA kinase plays a pivotal role in the regulation of growth, spore production, aflatoxin biosynthesis, and responses to rapamycin and cell membrane stress. As a significant downstream effector molecule of the TorA kinase, the Sch9 kinase regulates aflatoxin B1 (AFB1) synthesis, osmotic and calcium stress response in A. flavus, and this regulation is mediated through its S_TKc, S_TK_X domains, and the ATP-binding site at K340. We also showed that the Sch9 kinase may have a regulatory impact on the high osmolarity glycerol (HOG) signaling pathway. TapA and TipA, the other downstream components of the TorA kinase, play a significant role in regulating cell wall stress response in A. flavus. Moreover, the members of the TapA-phosphatase complexes, SitA and Ppg1, are important for various biological processes in A. flavus, including vegetative growth, sclerotia formation, AFB1 biosynthesis, and pathogenicity. We also demonstrated that SitA and Ppg1 are involved in regulating lipid droplets (LDs) biogenesis and cell wall integrity (CWI) signaling pathways. In addition, another phosphatase complex, Nem1/Spo7, plays critical roles in hyphal development, conidiation, aflatoxin production, and LDs biogenesis. Collectively, our study has provided important insight into the regulatory network of the TOR signaling pathway and has elucidated the underlying molecular mechanisms of aflatoxin biosynthesis in A. flavus.
Asunto(s)
Aspergillus flavus , Transducción de Señal , Serina-Treonina Quinasas TOR , Aspergillus flavus/metabolismo , Aspergillus flavus/genética , Aspergillus flavus/crecimiento & desarrollo , Aspergillus flavus/patogenicidad , Serina-Treonina Quinasas TOR/metabolismo , Proteínas Fúngicas/metabolismo , Proteínas Fúngicas/genética , Aflatoxinas/biosíntesis , Aflatoxinas/metabolismo , Regulación Fúngica de la Expresión Génica , VirulenciaRESUMEN
Biofilms are composed of complex multi-species in nature, potentially threatening drinking water safety. In this work, the formation of single- and multi-species fungal biofilms formed by Aspergillus niger (A. niger) and Aspergillus flavus (A. flavus), and the inactivation of mature biofilms using chlor(am)ine were firstly investigated. Results revealed that the antagonistic interaction occurred between A. niger and A. flavus. Chloramination at 20 mg/L for 30 min achieved 74.74 % and 76.04 % inactivation of A. flavus and multi-species biofilm, which were 1.69- and 1.84-fold higher than that of chlorine at the same condition. However, no significant difference was observed in the inactivation of A. niger biofilm between chlorine and monochloramine disinfection due to the lower amount of extracellular polymeric substance produced by it (p > 0.05). The inactivation of biofilm by monochloramine fitted the Weibull model well. According to the Weibull model, the monochloramine resistance of biofilm were as follows: A. flavus > multi-species > A. niger biofilm. Besides, an increase in reactive oxygen levels, damage of cell membrane, and leakage of intracellular substances in biofilms were observed after chlor(am)ination. More intracellular polysaccharides and proteins were leaked in chloramination inactivation (p < 0.05). This study provides important implications for controlling fungal biofilm.
Asunto(s)
Aspergillus flavus , Aspergillus niger , Biopelículas , Cloraminas , Desinfectantes , Desinfección , Biopelículas/efectos de los fármacos , Aspergillus niger/efectos de los fármacos , Cloraminas/farmacología , Desinfección/métodos , Desinfectantes/farmacología , Aspergillus flavus/efectos de los fármacos , Microbiología del Agua , Especies Reactivas de Oxígeno/metabolismo , Purificación del Agua/métodos , Farmacorresistencia Fúngica/efectos de los fármacosRESUMEN
BACKGROUND: The resistance of Aspergillus flavus to the azole antifungal drugs is an emerging problem. Mutations in the molecular targets of the azole antifungals - CYP 51 A, B and C - are possible mechanisms of resistance, but data to confirm this hypothesis are scarce. In addition, the behaviour of resistant strains in vitro and in vivo is not yet understood. OBJECTIVES: This study had 3 objectives. The first was to compare the sequences of CYP51 A, B and C in resistant and susceptible strains of A. flavus. The second was to look for the existence of a fitness cost associated with resistance. The third was to evaluate the activity of voriconazole and posaconazole on resistant strains in the Galleria mellonella model. METHODS: The CYP51 A, B and C sequences of seven resistant strains with those of four susceptible strains are compared. Fitness costs were assessed by growing the strains in RPMI medium and testing their virulence in G. mellonella larvae. In addition, G. mellonella larvae infected with strains of A. flavus were treated with voriconazole and posaconazole. RESULTS: In the CYP51A sequences, we found the A91T, C708T and A1296T nucleotide substitutions only in the resistant strains. The resistant strains showed a fitness cost with reduced in vitro growth and reduced virulence in G. mellonella. In vivo resistance to posaconazole is confirmed in a strain with the highest MIC for this antifungal agent. CONCLUSIONS: These results allow to conclude that some substitutions in CYP51 genes, in particular CYP51A, contribute to resistance to azole drugs in A. flavus. The study of the relationship between drug dosage and treatment duration with resistance and the reduction of fitness costs in resistant strains is a major perspective of this study. This work could help to establish recommendations for the treatment of infections with resistant strains of A. flavus.
Asunto(s)
Antifúngicos , Aspergillus flavus , Azoles , Sistema Enzimático del Citocromo P-450 , Farmacorresistencia Fúngica , Larva , Pruebas de Sensibilidad Microbiana , Voriconazol , Aspergillus flavus/efectos de los fármacos , Aspergillus flavus/genética , Antifúngicos/farmacología , Farmacorresistencia Fúngica/genética , Animales , Voriconazol/farmacología , Azoles/farmacología , Sistema Enzimático del Citocromo P-450/genética , Larva/microbiología , Triazoles/farmacología , Proteínas Fúngicas/genética , Mariposas Nocturnas/microbiología , Aspergilosis/microbiología , Aspergilosis/tratamiento farmacológico , Virulencia , Aptitud Genética , Modelos Animales de EnfermedadRESUMEN
Contamination of crop seeds and feed with Aspergillus flavus and its associated aflatoxins presents a significant threat to human and animal health due to their hepatotoxic and carcinogenic properties. To address this challenge, researchers have screened for potential biological control agents in peanut soil and pods. This study identified a promising candidate, a strain of the nonpigmented bacterium, Achromobacter xylosoxidans ZJS2-1, isolated from the peanut rhizosphere in Zhejiang Province, China, exhibiting notable antifungal and antiaflatoxin activities. Further investigations demonstrated that ZJS2-1 active substances (ZAS) effectively inhibited growth at a MIC of 60 µL/mL and nearly suppressed AFB1 production by 99%. Metabolomic analysis revealed that ZAS significantly affected metabolites involved in cell wall and membrane biosynthesis, leading to compromised cellular integrity and induced apoptosis in A. flavus through the release of cytochrome c. Notably, ZAS targeted SrbA, a key transcription factor involved in ergosterol biosynthesis and cell membrane integrity, highlighting its crucial role in ZJS2-1's biocontrol mechanism. Moreover, infection of crop seeds and plant wilt caused by A. flavus can be efficiently alleviated by ZAS. Additionally, ZJS2-1 and ZAS demonstrated significant inhibitory effects on various Aspergillus species, with inhibition rates ranging from 80 to 99%. These findings highlight the potential of ZJS2-1 as a biocontrol agent against Aspergillus species, offering a promising solution to enhance food safety and protect human health.
Asunto(s)
Achromobacter denitrificans , Aflatoxinas , Apoptosis , Arachis , Aspergillus flavus , Membrana Celular , Rizosfera , Aspergillus flavus/metabolismo , Aspergillus flavus/crecimiento & desarrollo , Arachis/microbiología , Arachis/química , Membrana Celular/metabolismo , Membrana Celular/efectos de los fármacos , Aflatoxinas/biosíntesis , Aflatoxinas/metabolismo , Apoptosis/efectos de los fármacos , Achromobacter denitrificans/metabolismo , Semillas/microbiología , Semillas/química , Semillas/metabolismo , Antifúngicos/farmacología , Antifúngicos/metabolismo , China , Enfermedades de las Plantas/microbiología , Enfermedades de las Plantas/prevención & control , Microbiología del SueloRESUMEN
Phellinus caribaeo-quercicola is a basidiomycetous fungus, isolated as an endophyte in this study from the healthy and symptomless leaves of Inula racemosa Hook. f., an important medicinal herb growing in Kashmir Himalaya. This study combines morphological, molecular and phylogenetic techniques to identify the fungal endophyte, using the ITS sequence of nrDNA. A detached leaf assay was conducted to assess the pathogenicity of the fungal endophyte suggesting its mutually symbiotic relationship with the host. The authors also investigated the antifungal potential of the isolated endophytic strain to ascertain its use as a biocontrol agent. The study shows that P. caribaeo-quercicola INL3-2 strain exhibits biocontrol activity against four key fungal phytopathogens that cause significant agronomic and economic losses: Aspergillus flavus, Aspergillus niger, Fusarium solani, and Fusarium oxysporum. Notably, P. caribaeo-quercicola INL3-2 strain is highly effective against A. flavus, with an inhibition percentage of 57.63%. In addition, this study investigates the antioxidant activity of P. caribaeo-quercicola INL3-2 strain crude extracts using ethyl acetate and methanol as solvents. The results showed that the methanolic fraction of P. caribaeo-quercicola exhibits potential as an antioxidant agent, with an IC50 value of 171.90 ± 1.15 µg/mL. This investigation is first of its kind and marks the initial report of this fungal basidiomycete, P. caribaeo-quercicola, as an endophyte associated with a medicinal plant. The findings of this study highlight the potential of P. caribaeo-quercicola INL3-2 strain as a dual-action agent with both biocontrol and antioxidant properties consistent with the medicinal properties of Inula racemosa. This endophytic fungus could be a promising source of natural compounds for use in agriculture, medicine, and beyond.
Asunto(s)
Antifúngicos , Antioxidantes , Basidiomycota , Endófitos , Filogenia , Hojas de la Planta , Endófitos/aislamiento & purificación , Endófitos/metabolismo , Endófitos/fisiología , Endófitos/genética , Antioxidantes/farmacología , Antioxidantes/metabolismo , Basidiomycota/efectos de los fármacos , Hojas de la Planta/microbiología , Antifúngicos/farmacología , Antifúngicos/metabolismo , Fusarium/efectos de los fármacos , Enfermedades de las Plantas/microbiología , Enfermedades de las Plantas/prevención & control , Agentes de Control Biológico/farmacología , Aspergillus/metabolismo , Aspergillus/efectos de los fármacos , India , Aspergillus flavus/efectos de los fármacos , Aspergillus flavus/metabolismo , Aspergillus flavus/crecimiento & desarrollo , ADN de Hongos/genética , SimbiosisRESUMEN
Chemical pesticides help reduce crop loss during production and storage. However, the carbon footprints and ecological costs associated with this strategy are unsustainable. Here, we used three in vitro models to characterize how different Trichoderma species interact with two aflatoxin producers, Aspergillus flavus and Aspergillus parasiticus, to help develop a climate-resilient biological control strategy against aflatoxigenic Aspergillus species. The growth rate of Trichoderma species is a critical factor in suppressing aflatoxigenic strains via physical interactions. The dual plate assay suggests that Trichoderma mainly suppresses A. flavus via antibiosis, whereas the suppression of A. parasiticus occurs through mycoparasitism. Volatile organic compounds (VOCs) produced by Trichoderma inhibited the growth of A. parasiticus (34.6 ± 3.3%) and A. flavus (20.9 ± 1.6%). The VOCs released by T. asperellum BTU and T. harzianum OSK-34 were most effective in suppressing A. flavus growth. Metabolites secreted by T. asperellum OSK-38, T. asperellum BTU, T. virens OSK-13, and T. virens OSK-36 reduced the growth of both aflatoxigenic species. Overall, T. asperellum BTU was the most effective at suppressing the growth and aflatoxin B1 production of both species across all models. This work will guide efforts to screen for effective biological control agents to mitigate aflatoxin accumulation.