Strains Of Aspergillus Flavus Research Articles

Elucidating Mycotoxin-Producing Aspergillus Species in River Water: An Advanced Molecular Diagnostic Study for the Assessment of Ecological Health and Contamination Risk

The primary goal of this research is to isolate mycotoxin-producing fungus from the Nagavali River. Examining isolated fungi involved analyzing their mycelium growth on culture media and detailed microscopic inspection. We employed PCR analysis utilizing universal primers ITS1 and ITS4 to accurately identify the species. Furthermore, we sequenced the amplified ITS region and rigorously analyzed the sequences using NCBI-BLASTn and the ITS2 database. The analysis found a high 96.38% genetic similarity to the Aspergillus flavus strain, resulting in a 600-base pair fragment size. The sequence was given the accession number OR536222 in the NCBI GenBank database. Phylogenetic analysis was performed to ascertain the particular strain of A. flavus and its source. Remarkably, this analysis led to the identification of a single new strain gene, which represents a novel discovery in the field of fungal research. These results underscore the vital significance of molecular techniques in promptly and precisely identifying organisms. This research enhances our understanding of mycotoxin contamination in water, providing valuable insights to improve detection and prevention strategies. It accentuates the overarching importance of conserving our water resources and upholding ecological equilibrium, ultimately safeguarding the well-being of both humanity and the environment.

Application of Cystoseira myrica phycosynthesized selenium nanoparticles incorporated with nano-chitosan to control aflatoxigenic fungi in fish feed.

The recurrent contaminations of feed materials with mycotoxigenic fungi can endanger both farmed animals and humans. Biosynthesized nanomaterials are assumingly the ideal agents to overcome fungal invasion in feed/foodstuffs, especially when utilizing sustainable sources for synthesis. Herein, the phycosynthesis of selenium nanoparticles (SeNPs) was targeted using Cystoseira myrica algal extract (CE), and the conjugation of CE/SeNPs with chitosan nanoparticles (NCt) to produce potential antifungal nanocomposites for controlling Aspergillus flavus isolates in fish feed. The phycosynthesis of SeNPs with CE was effectually carried out and validated using visible/UV analysis, X-ray diffraction and transmission microscopy; CE/SeNPs had diameters of 8.7 nm and spherical shapes. NCt/CE/SeNPs nanocomposite (173.3 nm mean diameter) was achieved and the component interactions were validated via infrared spectroscopic analysis. The antifungal assessment of screened nanomaterials against three Aspergillus flavus strains indicated that NCt/CE/SeNPs exceeded the fluconazole action using qualitative/quantitative assays. Severe alteration/distortions in A. flavus mycelial structure and morphology were microscopically observed within 48 h of NCt/CE/SeNPs treatment. The treatment of feed ingredients (crushed corn and feed powder) by blending with nanomaterials (NCt, CE/SeNPs and NCt/CE/SeNPs) led to significant reduction in A. flavus count/growth after storage for 7 days; NCt/CE/SeNPs could completely inhibit any fungal growth in feed material. The pioneering phycosynthesis of CE/SeNPs and their nanoconjugation with NCt generated bioactive antifungal agents to control A. flavus strains. The innovatively constructed NCt/CE/SeNPs nanocomposite is advised for application as an effectual, biosafe and natural fungicidal conjugate for the protection of fish feed from mycotoxigenic fungi. © 2024 Society of Chemical Industry.

Molecular Identification of Ascomycetes from American Cranberry (Vaccinium macrocarpon Aiton) Grown in Plantation in Poland

The American cranberry is a perennial North American fruit plant that is grown successfully on commercial plantations in Poland. The purpose of this study was to recognize filamentous fungi that colonize roots, leaves, and fruits without visible disease symptoms. Pure fungal cultures were isolated from disinfected plant fragments in agar media and identified by sequencing common taxonomic DNA markers such as the ITS region, the TEF-1α, or RPB2 genes. Of the 141 isolates studied, 59% were identified as closely related to soil saprotrophs. They were classified primarily as showing the greatest similarity to type strains of Trichoderma amoenum, Trichoderma dorothopsis, Paraphaeosphaeria sporulosa, and Penicillium murcianum. Additionally, isolates that are most similar to strains of Penicillium crustosum, Aspergillus flavus, and Aspergillus versicolor that produced mycotoxins were detected. The fungi identified as closest to Alternaria geophila, Alternaria senecionicola, Paraphoma radicina, Pestalotiopsis unicolor, Pestalotiopsis scoparia, and Neopestalotiopsis spp., whose hosts are plants other than American cranberry, represented 33.81% of the isolates tested. Only 7.2% of the isolates corresponded to the species of Physalospora vaccinia, Diaporthe vaccinii, and Diaporthe eres, known cranberry pathogens. The results of this study can be used to identify latent plant infection and potential disease risks.

Divergent Aspergillus flavus corn population is composed of prolific conidium producers: Implications for saprophytic disease cycle

ABSTRACT The ascomycete fungus Aspergillus flavus infects and contaminates corn, peanuts, cottonseed, and tree nuts with toxic and carcinogenic aflatoxins. Subdivision between soil and host plant populations suggests that certain A. flavus strains are specialized to infect peanut, cotton, and corn despite having a broad host range. In this study, the ability of strains isolated from corn and/or soil in 11 Louisiana fields to produce conidia (field inoculum and male gamete) and sclerotia (resting bodies and female gamete) was assessed and compared with genotypic single-nucleotide polymorphism (SNP) differences between whole genomes. Corn strains produced upward of 47× more conidia than strains restricted to soil. Conversely, corn strains produced as much as 3000× fewer sclerotia than soil strains. Aspergillus flavus strains, typified by sclerotium diameter (small S-strains, <400 μm; large L-strains, >400 μm), belonged to separate clades. Several strains produced a mixture (M) of S and L sclerotia, and an intermediate number of conidia and sclerotia, compared with typical S-strains (minimal conidia, copious sclerotia) and L-strains (copious conidia, minimal sclerotia). They also belonged to a unique phylogenetic mixed (M) clade. Migration from soil to corn positively correlated with conidium production and negatively correlated with sclerotium production. Genetic differences correlated with differences in conidium and sclerotium production. Opposite skews in female (sclerotia) or male (conidia) gametic production by soil or corn strains, respectively, resulted in reduced effective breeding population sizes when comparing male:female gamete ratio with mating type distribution. Combining both soil and corn populations increased the effective breeding population, presumably due to contribution of male gametes from corn, which fertilize sclerotia on the soil surface. Incongruencies between aflatoxin clusters, strain morphotype designation, and whole genome phylogenies suggest a history of sexual reproduction within this Louisiana population, demonstrating the importance of conidium production, as infectious propagules and as fertilizers of the A. flavus soil population.

Extraction Kinetics and Antifungal Activities of Essential Oil from the Aerial Parts of Gros Baume (Hyptis suaveolens) Against Three Fungal Strains in Côte d'Ivoire

Introduction: Microscopic fungi colonize many food substrates resulting in considerable economic losses. Their development leads to an alteration in the organoleptic quality of the food, and produces mycotoxins. The aim of the present work was to evaluate the extraction kinetics and in vitro antifungal activity of the essential oil of Hyptis suaveolens on the growth of three toxigenic fungal strains. Methodology: The essential oil was extracted by steam distillation using a Clevenger-type device. It was tested for in vitro antifungal activity against three mold strains (Aspergillus flavus, Aspergillus niger and Fusarium sp) using the agar dilution method. Results: The results of the extraction kinetics evaluation show that in fifty minutes of distillation, almost all the essential oil contained in the aerial parts of H. suaveolens is recovered. In vitro antifungal tests showed a slight slowdown in mycelial growth for the three strains studied. However, the antifungal parameters determined show that these strains are sensitive to 50 μL/mL with a CMF of 100 μL/mL. This is just a simple fungistatic effect of this extract on the mycelial growth of the strains tested. Aspergillus strains seem to be slightly more affected than Fusarium strains. Conclusion: The antifungal potential of H. suaveolens essential oil does not offer a novel approach to the control of these three fungal strains.

Green synthesis of CuO nanoparticles using Ligustrum lucidum extract, and the antioxidant and antifungal evaluation

Biosynthesis of metal oxide nanoparticles using plant extract is an inexpensive, simple, rapid, and environmentally friendly approach to obtaining nanoparticles for biological applications. Herein, copper oxide nanoparticles (CuO-NPs) were successfully synthesized using an aqueous extract from Ligustrum lucidum leaves. The structural, optical, and morphological characteristics of the nanoparticles were assessed using x-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, UV-visible spectrophotometer, transmission and scanning electron microscopy (TEM and SEM), and energy-dispersive x-ray (EDX). Nanocrystalline CuO with an average crystalline size of 22.0 nm and a band gap energy of 1.4 eV were confirmed from the XRD and UV-vis spectrophotometer, respectively. Morphological studies showed spherical nanoparticles, whose particle size estimation (30 ± 5 nm) agrees with the crystalline size deduced from the XRD pattern. A free radical scavenging activity of the CuO nanoparticles, evaluated using the 1, 1-diphenhyl-2-picrylhydrazyl (DPPH) assay, showed that it exhibited high antioxidant activity (IC50: 63.35 μg ml−1) that is concentration dependent. Antifungal evaluation using four different fungal strains (Aspergillus flavus, Aspergillus niger, Fusarium oxysporum, and Trichoderma harzianum) indicated a direct relationship between the potency of the particles and their concentration, with 1 ppm solution exhibiting the highest potency. The green synthesized CuO-NPs using Ligustrum lucidum may be potentially used as an antioxidant and antifungal agent for therapeutic applications.

Beta maritima mediated silver Nanoparticles: Characterization and evaluation of Antibacterial, Antifungal, and antioxidant activities

Silver nanoparticles (AgNPs) are known for their large surface area, which enhances their energy and antimicrobial activity. This study focused on producing silver nanoparticles using leaves from the Beta maritima (vulgaris) plant. Various techniques such as Fourier transform infrared (FT-IR) spectroscopy, ultraviolet–visible (UV–vis) spectroscopy, energy-dispersive X-ray spectroscopy (EDX), scanning electron microscopy (SEM), and X-ray diffraction analysis (XRD) to characterize the synthesized AgNPs. The biologically synthesized AgNPs were then evaluated for their antimicrobial (antibacterial and antifungal) and antioxidant properties using different agents such as hydrogen peroxide (H2O2), 1,1-Diphenyl-2-picrylhydrazyl (DPPH), 2,2 azobis, 3-ethyl benzothiazoline-6-sulphonic acid (ABTS), and phosphomolybdate. The results showed that the AgNPs exhibited strong antifungal activity, particularly against fluconazole-resistant strains of Aspergillus niger and Aspergillus flavus, with a 61 % inhibition rate. Moreover, the AgNPs demonstrated significant antibacterial activity against various strains. At a concentration of 40 µg/mL, they exhibited 26 % inhibition against Staphylococcus aureus, 22 % against Micrococcus luteus, 18 % against E. coli, and 24 % against Klebsiella pneumonia, outperforming clarithromycin antibiotics. SEM analysis revealed spherical AgNPs, sized using nano measurer 1.2, EDX showed the presence of silver having composition at 80.38 %, and XRD confirmed a face-centered cubic crystalline structure. In addition to their characterization, the AgNPs also displayed strong antioxidant activity. At the same concentration, they showed percentages of 80.78 % (DPPH), 85.38 % (H2O2), 81.78 % (ABTS), and 80.66 % (phosphomolybdate), surpassing the antioxidant activity of the plant leaf extract alone. The synthesis of AgNPs using the extract of the Beta maritima (vulgaris) plant offers several advantages compared to other methods, including ease of handling, cost-effectiveness, wide availability, and eco-friendliness.

Mycoremediation of the novel fungicide ametoctradin by different agricultural soils and accelerated degradation utilizing selected fungal strains

Accelerating safety assessments for novel agrochemicals is imperative, advocating for in vitro setups to present pesticide biodegradation by soil microbiota before field studies. This approach enables metabolic profile generation in a controlled laboratory environment eliminating extrinsic factors. In the current study, ten different soil samples were utilized to check their capability to degrade Ametoctradin by their microbiota. Furthermore, five different fungal strains (Aspergillus niger, Aspergillus flavus, Aspergillus fumigatus, Lasiodiplodia theobromae, and Penicillium chrysogenum) were utilized to degrade Ametoctradin in aqueous media. A degradation pathway was established using the metabolic patterns created during the biodegradation of Ametoctradin. In contrast to 47% degradation (T1/2 of 34 days) when Ametoctradin was left in the soil samples, the fungal strain Aspergillus fumigatus demonstrated 71% degradation of parent Ametoctradin with a half-life (T1/2) of 16 days. In conclusion, soil rich in microorganisms effectively cleans Ametoctradin-contaminated areas while Fungi have also been shown to be an effective, affordable, and promising way to remove Ametoctradin from the environment.

Morphed aflaxotin concentration produced by Aspergillus flavus strain VKMN22 on maize grains inoculated on agar culture

This study identified and monitored the levels of aflatoxins (B1 and B2) produced by Aspergillus flavus isolate VKMN22 (OP355447) in maize samples sourced from a local shop in Johannesburg, South Africa. Maize samples underwent controlled incubation after initial rinsing, and isolates were identified through morphological and molecular methods. In another experiment, autoclaved maize grains were intentionally re-inoculated with the identified fungal isolate using spore suspension (106 spore/mL), after which 1 g of the contaminated maize sample was inoculated on PDA media and cultured for seven days. The aflatoxin concentrations in the A. flavus contaminated maize inoculated on culture media was monitored over seven weeks and then measured using liquid chromatography–mass spectroscopy (LC-MS). Results confirmed the successful isolation of A. flavus strain VKMN22 with accession number OP355447, which consistently produced higher levels of AFB1 compared to AFB2. AF concentrations increased from week one to five, then declined in week six and seven. AFB1 levels ranged from 594.3 to 9295.33 µg/kg (week 1–5) and then reduced from 5719.67 to 2005 µg/kg in week six and seven), while AFB2 levels ranged from 4.92 to 901.67 µg/kg (weeks 1–5) and then degraded to 184 µg/kg in week six then 55.33 µg/kg (weeks 6–7). Levene's tests confirmed significantly higher mean concentrations of AFB1 compared to AFB2 (p ≤ 0.005). The study emphasizes the importance of consistent biomonitoring for a dynamic understanding of AF contamination, informing accurate prevention and control strategies in agricultural commodities thereby safeguarding food safety.

Response of broilers to dietary inclusion of atoxigenic Aspergillus flavus strain as a biocontrol strategy of aflatoxin

ABSTRACT The objective of this trial was to evaluate how broilers responded to Aspergillus flavus strains that are toxigenic and atoxigenic. The study included four treatments in a 2 × 2 factorial design, with six replicates of 10 birds each. As a result of this study measuring feed intake (FI), weight gain (WG), feed conversion ratio (FCR), crude protein, ether extract, and crude fibre, the interaction was insignificant between the toxigenic and atoxigenic diets (P > 0.05). Consumption of toxigenic aflatoxin B1-500 ppb diet decreased FI and WG but increased FCR, and cost to produce live broiler weight (P < 0.05) compared to the control diets. The addition of atoxigenic strains to contaminated diets significantly offset (P < 0.05) the effects. Diets with or without 500 ppb toxigenic and atoxigenic A. flavus did not affect the relative weight g/100gBW of pancreas, gizzard and bursa of Fabricius. Dietary inclusion of 500 ppb toxigenic Aspergillus spp. increased the relative weight (P < 0.05) of the kidney, liver, spleen and thymus while atoxigenic dietary addition reduced the relative weight of the same organs (P < 0.05). Dietary inclusion of toxigenic and atoxigenic Aspergillus spp. did not significantly affect the haematological parameters measured (P < 0.05). Dietary inclusion of 500 ppb toxigenic Aspergillus elevated the urea, creatine, alanine aminotransferase (ALT), aspartate aminotransferase (AST) and alkaline phosphatase (ALP) in the serum of the broilers (P < 0.05). A decrease was observed when atox igenic A. flavus was used in the intervention for urea, creatinine and AST (P < 0.05), whereas an insignificant reduction was observed for ALT and ALP (P ≤ 0.05). This study concluded that dietary atoxigenic strain improved broiler performance, digestibility, and blood parameters.

An Aspergillus flavus strain from bee bread of the Western honey bee (Apis mellifera) displays adaptations to distinctive features of the hive environment.

Aspergillus fungi are ubiquitous inhabitants of colonies of the western honey bee (Apis mellifera), where they interact with bees in associations ranging from parasitism to possible mutualism. Aspergillus Flavi fungi are frequently found in bee bread (pollen processed for longterm storage) and are thought to contribute to food preparation, processing, preservation, and digestion. Conditions in the hive are challenging for fungi due, in part, to xeric and acidic properties of bee bread and the omnipresence of propolis, an antimicrobial product manufactured by bees from plant resins. We used quantitative and qualitative assays to determine whether A. flavus isolated from bee bread demonstrates tolerance for hive environmental conditions in terms of temperature, pH, osmotic pressure, and propolis exposure. Comparisons made use of three strains of A. flavus: a fungal biocontrol product not known from beehives (AF36), a strain isolated from bee bread (AFBB) in hives from central Illinois, and a pathogenic strain from a honey bee colony displaying symptoms of stonebrood (AFPA). Strain AFBB displayed higher tolerance of acidic conditions, low matric potential (simulating xeric substrate), and propolis exposure than did other strains. A genomic comparison between this new strain and the reference NRRL-3357 showed that AFBB, like AF36, might be blocked from carrying out aflatoxin biosynthesis. Sequence comparisons also revealed several missense variants in genes that encode proteins regulating osmotolerance and osmotic pressure in Aspergillus spp., including SakA, SskB, GfdA, and TcsB/Sln1. Collectively, results of our laboratory assays and genetic analyses are consistent with the suggestion that the strain isolated from bee bread is adapted to the bee bread environment and may have persisted due to a coevolutionary relationship between Aspergillus and A. mellifera. This finding bolsters recent concerns about the effects of fungicide use near bee colonies and broadens the ecological importance of highly adaptable fungal strains.

Assessment and Mitigation of Bacterial and Fungal Contamination in Refrigerator Waterlines

Three experiments were conducted on the recovery of microorganisms associated with refrigerator water lines. In the first experiment, between 2 and 3 logs CFU/ml were recovered from 100 different refrigerators’ residential water and ice lines. In a second experiment, plastic tubing segments cut from commercial refrigerator waterline systems were inoculated with the bacterium Pseudomonas aeruginosa and a fungal strain of Aspergillus flavus. Either 0.02% peracetic acid (PAA) exposure for 2 min or 0.03% PAA exposure for 1 min resulted in no recoverable bacteria cells, however, 0.25% PAA contact for 2 min was needed to eliminate detection of fungal cells. The third experiment tested sanitation of a water system inoculated with a mixed culture of P. aeruginosa and A flavus with a water filter cartridge filled with 3.5% PAA. The 3.5% concentration was determined using a computer simulation for mixing during a cleaning cycle that would yield a minimum concentration of at least 0.25% throughout the water system. After loading a water filter cartridge containing 3.5% PAA, allowing water to flow into the system for 15 s, and then allowing the system to sit for 5 min, no viable P. aeruginosa or A flavus cells were recovered up to 10 days after treatment.

Biotransformation of the azo dye reactive orange 16 by Aspergillus flavus A5P1: Performance, genetic background, pathway, and mechanism

This study reports the strain Aspergillus flavus A5P1 (A5P1), which is with the capable of degrading the azo dye reactive orange 16 (RO16). The mechanism of RO16 degradation by A5P1 was elucidated through genomic analysis, enzymatic analysis, degradation pathway analysis and oxidative stress analysis. Strain A5P1 exhibited aerobic degradation of RO16, with optimal degradation at an initial pH of 3.0. Genomic analysis indicates that strain A5P1 possesses the potential for acid tolerance and degradation of azo dye. Enzymatic analysis, combined with degradation product analysis, demonstrated that extracellular laccase, intracellular lignin peroxidase, and intracellular quinone reductase were likely key enzymes in the RO16 degradation process. Oxidative stress analysis revealed that cell stress responses may participate in the RO16 biotransformation process. The results indicated that the biotransformation of RO16 may involves biological processes such as transmembrane transport of RO16, cometabolism of the strain with RO16, and cell stress responses. These findings shed light on the biodegradation of RO16 by A5P1, indicating A5P1′s potential for environmental remediation.

Inhibition of Aflatoxin B1 by Aqueous extract from Green Cardamom

Aflatoxin B1 is a secondary metabolite produced by Aspergillus section Flavi during their development, is one of the most dangerous mycotoxins identified to date, that may contaminate many commodities, especially in tropical and sub-tropical regions. Aflatoxin B1 is believed to be the most essential member of this family of mycotoxins, due to its carcinogenic properties in humans and animals. However, there are many strategies to prevent mycotoxin contamination in which some of them are based on the use of natural compounds that may able to minimize the toxin synthesis pathways. Aims: The current work aimed to identify specific compounds from Green Cardamom that expected to interfere with aflatoxin production pathway. Methodology: The adapted method was based on the incubation of fungal culture with different concentrations of the aqueous extraction of Green Cardamom. Results: The aqueous extract of Green Cardamom was able to inhibit Fungal growth and Aflatoxin B1 production by the toxigenic strain of Aspergillus Flavus in a dose-dependent manner. Discussion: the reduction of Aflatoxin B1 production was significantly higher (94.34%) in comparison with other plant extracts such as Caffeine (50%), and reduced fungal growth with an average of (4%) compared to control. Conclusion: Aqueous Extracts of Green Cardamom show an obvious reduction in inhibition synthesis of Aflatoxin B1 by toxigenic Aspergillus strain, the adapted method was effective, but even further investigation is still recommended.

Structural and functional characterization of a new thermophilic-like OYE from Aspergillus flavus

Old yellow enzymes (OYEs) have been proven as powerful biocatalysts for the asymmetric reduction of activated alkenes. Fungi appear to be valuable sources of OYEs, but most of the fungal OYEs are unexplored. To expand the OYEs toolbox, a new thermophilic-like OYE (AfOYE1) was identified from Aspergillus flavus strain NRRL3357. The thermal stability analysis showed that the T1/2 of AfOYE1 was 60 °C, and it had the optimal temperature at 45 °C. Moreover, AfOYE1 exhibited high reduction activity in a wide pH range (pH 5.5–8.0). AfOYE1 could accept cyclic enones, acrylamide, nitroalkenes, and α, β-unsaturated aldehydes as substrates and had excellent enantioselectivity toward prochiral alkenes (> 99% ee). Interestingly, an unexpected (S)-stereoselectivity bioreduction toward 2-methylcyclohexenone was observed. The further crystal structure of AfOYE1 revealed that the “cap” region from Ala132 to Thr182, the loop of Ser316 to Gly325, α short helix of Arg371 to Gln375, and the C-terminal “finger” structure endow the catalytic cavity of AfOYE1 quite deep and narrow, and flavin mononucleotide (FMN) heavily buried at the bottom of the active site tunnel. Furthermore, the catalytic mechanism of AfOYE1 was also investigated, and the results confirmed that the residues His211, His214, and Tyr216 compose its catalytic triad. This newly identified thermophilic-like OYE would thus be valuable for asymmetric alkene hydrogenation in industrial processes.Key pointsA new thermophilic-like OYE AfOYE1 was identified from Aspergillus flavus, and the T1/2of AfOYE1 was 60 °CAfOYE1 catalyzed the reduction of 2-methylcyclohexenone with (S)-stereoselectivityThe crystal structure of AfOYE1 was revealedv

Determination of Aflatoxins in Pig Feed. Using the Thin Layer Chromatography Technique

Aflatoxins are the most important mycotoxins in terms of food safety, due to their frequency and toxicity, they are characterized by being secondary metabolites synthesized by fungi. In order to determine the presence of aflatoxins in pork feed, five samples from different commercial companies were analyzed. The methodology used prior to the sample extraction process was the thin layer chromatography technique, observed using long-wave ultraviolet light. It could be seen in samples 1,3,4,5, the presence of Aflatoxins, toxicogenic strains of Aspergillus parasiticus, which produce aflatoxins, G1 and G2, is characterized by the fluorescence coloration, in sample 2 the presence was observed of aflatoxins toxicogenic strains of Aspergillus flavus. Toxigenic strains of Aspergillus flavus generally produce only aflatoxins B1 and B2, while toxicogenic strains of Aspergillus parasiticus produce aflatoxins B1, B2, G1 and G2. AFB1 aflatoxins have been considered obvious carcinogens in experimental animals. It is important to carry out systematic research with low-cost analytical techniques to understand the mechanisms of production and action of aflatoxins in foods, in order to prevent, monitor and control these types of toxins.

ANTIFUNGAL ACTIVITY OF Pediococcus pentosaceus ISOLATED FROM BAMBARA GROUNDNUT (Vigna subterranea (L.) Verdc.) SEEDS AGAINST Aspergillus flavus

In this study, 22 lactic acid bacterial (LAB) strains were isolated from Bambara groundnut seeds and assessed for their ability to suppress the development of two strains of aflatoxigenic Aspergillus flavus. The antifungal activity of LAB strains was assessed via the overlay assay. Also, HPLC methodology was used to quantify the production of lactic and acetic acid by the LAB strains with high antifungal activity. After incubation at 30°C for 72 hours, five of these LAB strains (52B1, 52C1, 74B3, 67B1, 67A9) showed high inhibitory activity against Aspergillus flavus strains. These LAB strains exhibiting antifungal potential were identified as Pediococcus pentosaceus through 16S rDNA sequencing. Furthermore, the lactic acid bacteria (LAB) strains reported lactic acid production ranging from 12.08 mg/ml to 15.38 mg/ml and acetic acid production ranging from 0.06 mg/ml to 1.68 mg/ml. Notably, antifungal experiments are conducted in a controlled setting. Further, it would be worthwhile to explore the direct application of Pediococcus pentosaceus strains or their antimicrobial agents to food products to prevent fungal growth during storage. By doing so, the use of fungicides can be avoided and lead to safer food products.

Peanut (Arachis hypogea) accessions differentially accumulate aflatoxins upon challenge by Aspergillus flavus: Implications for aflatoxin mitigation

Peanut is among the most important oil crops grown in sub-Saharan Africa for its nutritive value and economic benefit. In this region, Aspergillus flavus infects peanuts and contaminates produce with aflatoxins leading to food insecurity through lowered quality. The impact of aflatoxins transcends the food chain causing harm to human and animal health. The selection and production of aflatoxin-tolerant varieties of peanut is a promising strategy to mitigate their potential harm. We studied the resistance of peanut kernels to aflatoxin accumulation in 25 peanut accessions collected from different growing locations in Kenya, Uganda, and Rwanda based on their unique phenotypic characteristics. To obtain sufficient planting material, the peanut accessions were multiplied separately under standard conditions and harvested at their respective maturity dates then dried and stored at 4 °C before further analysis. At the start of the experiment, the kernels were challenged with a laboratory-characterized toxigenic strain (Aspergillus flavus 1EM1901) and incubated at 28 °C for 7 days. Afterward, the accessions were analysed (ELISA) for aflatoxins. Of the 25 accessions tested, 60 % (n = 15) exhibited kernel resistance to aflatoxin accumulation while 40 % (n = 10) were susceptible (with aflatoxin levels ranging from 0.54 ppb to 1692.92 ppb). Two of the resistant accessions recorded a decrease in aflatoxin accumulation when challenged with toxigenic A. flavus. This differential accumulation of aflatoxins suggests the existence of an inherent trait that can be exploited in breeding programs of peanut varieties with low aflatoxin accumulation when grown in contaminated soils. These findings are further discussed.

Discovery, Identification, and Insecticidal Activity of an Aspergillus flavus Strain Isolated from a Saline-Alkali Soil Sample.

Aphids are one of the most destructive pests in agricultural production. In addition, aphids are able to easily develop resistance to chemical insecticides due to their rapid reproduction and short generation periods. To explore an effective and environmentally friendly aphid control strategy, we isolated and examined a fungus with aphid-parasitizing activity. The strain (YJNfs21.11) was identified as Aspergillus flavus by ITS, 28S, and BenA gene sequence analysis. Scanning electron microscopy and transmission electron microscopy revealed that the infection hyphae of 'YJNfs21.11' colonized and penetrated the aphid epidermal layer and subsequently colonized the body cavity. Field experiments showed that 'YJNfs21.11' and its fermentation products exerted considerable control on aphids, with a corrected efficacy of 96.87%. The lipase, protease, and chitinase secreted by fungi help aphid cuticle degradation, thus assisting spores in completing the infection process. Additionally, changes were observed in the mobility and physical signs of aphids, with death occurring within 60 h of infection. Our results demonstrate that A. flavus 'YJNfs21.11' exhibits considerable control on Aphis gossypii Glover and Hyalopterus arundimis Fabricius, making it a suitable biological control agent.

Synthesis, Spectroscopic and Nonlinear Optical Properties, and Antimicrobial Activity of Cu(II), Co(II), and Ni(II) Complexes: Experimental and Theoretical Studies.

Currently, we report the preparation of transition metal complexes Co(II), Ni(II), and Cu(II) of hydrazone Schiff base ligands, which are obtained by the condensation reaction of substituted salicylaldehyde and hydrazines. The synthesized hydrazone ligands and their metal complexes were characterized by spectroscopic methods such as Fourier transform infrared (FT-IR), UV-vis, nuclear magnetic resonance (1H NMR and C13 NMR), and mass spectrometry analyses. All of the quantum chemistry calculations were performed using DFT executed in the Gaussian 09 software package. The geometry was optimized by using the density functional theory (DFT) approximation at the B3LYP level with a basis set of 6-31G (d, p). There was excellent agreement between the FT-IR values obtained experimentally and those obtained theoretically for the test compounds. It is worth noting that none of the optimized geometries for any of the Schiff base and metal complexes had any eigenvalues that were negative, indicating that these geometries represent the true minimum feasible energy surfaces. We also analyzed the electrostatic potential of the molecule and NBO calculation at the same level of theory. Gauss View 6 was utilized for the file organization of the input data. Gauss View 6.0, Avogadro, and Chemcraft were used to determine the data. Additionally, synthesized compounds were screened for antimicrobial activity against Gram-negative bacteria (Salmonella typhi, Escherichia coli) and Gram-positive bacteria (Bacillus halodurans, Micrococcus luteus) and two fungal strains (Aspergillus flavus, Aspergillus niger). These research findings have established the potential of ligands and their metal complexes as antimicrobial agents. Additionally, the compounds demonstrated promising nonlinear optical (NLO) properties, with potential applications across a wide range of contemporary technologies.