Aflatoxigenic Aspergillus Flavus Research Articles

Three Ecological Models to Evaluate the Effectiveness of Trichoderma spp. for Suppressing Aflatoxigenic Aspergillus flavus and Aspergillus parasiticus.

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.

Reduction of aflatoxins and ochratoxin A by addition of commercial Koji during fermentation of the Korean traditional soybean paste, Doenjang

Contamination by aflatoxins and ochratoxin A of traditional Korean fermented soybean paste (Doenjang) is a serious food safety issue. In this study, we investigated the inhibitory effects of commercial Koji, a microbial starter culture used for fermentation, on mycotoxin contamination during Doenjang production at in vitro and scaled-up fermentation levels. A commercial Koji dominated by Aspergillus oryzae JI-4 exhibited strong antifungal and antimycotoxigenic activities against aflatoxigenic Aspergillus flavus and ochratoxigenic Penicillium verrucosum both in vitro and in situ. Furthermore, co-inoculation with Koji JI and mycotoxigenic fungi in the early stage of Doenjang fermentation significantly suppressed aflatoxins and ochratoxin A production by more than 93% (p < 0.05) and improved the nutritional properties and sensory qualities of the final product. These results suggest that the addition of commercial Koji could be an effective and practical approach to reduce aflatoxins and ochratoxin A contamination during the fermentation of soybean paste.

Inhibition of Aflatoxin Production in Aspergillus flavus by a Klebsiella sp. and Its Metabolite Cyclo(l-Ala-Gly).

During an experiment where we were cultivating aflatoxigenic Aspergillus flavus on peanuts, we accidentally discovered that a bacterium adhering to the peanut strongly inhibited aflatoxin (AF) production by A. flavus. The bacterium, isolated and identified as Klebsiella aerogenes, was found to produce an AF production inhibitor. Cyclo(l-Ala-Gly), isolated from the bacterial culture supernatant, was the main active component. The aflatoxin production-inhibitory activity of cyclo(l-Ala-Gly) has not been reported. Cyclo(l-Ala-Gly) inhibited AF production in A. flavus without affecting its fungal growth in a liquid medium with stronger potency than cyclo(l-Ala-l-Pro). Cyclo(l-Ala-Gly) has the strongest AF production-inhibitory activity among known AF production-inhibitory diketopiperazines. Related compounds in which the methyl moiety in cyclo(l-Ala-Gly) is replaced by ethyl, propyl, or isopropyl have shown much stronger activity than cyclo(l-Ala-Gly). Cyclo(l-Ala-Gly) did not inhibit recombinant glutathione-S-transferase (GST) in A. flavus, unlike (l-Ala-l-Pro), which showed that the inhibition of GST was not responsible for the AF production-inhibition of cyclo(l-Ala-Gly). When A. flavus was cultured on peanuts dipped for a short period of time in a dilution series bacterial culture broth, AF production in the peanuts was strongly inhibited, even at a 1 × 104-fold dilution. This strong inhibitory activity suggests that the bacterium is a candidate for an effective biocontrol agent for AF control.

Macro-micro exploration on dynamic interaction between aflatoxigenic Aspergillus flavus and maize kernels using Vis/NIR hyperspectral imaging and SEM technology

Aspergillus flavus and its toxic metabolites-aflatoxins infect and contaminate maize kernels, posing a threat to grain safety and human health. Due to the complexity of microbial growth and metabolic processes, dynamic mechanisms among fungal growth, nutrient depletion of maize kernels and aflatoxin production is still unclear. In this study, visible/near infrared (Vis/NIR) hyperspectral imaging (HSI) combined with the scanning electron microscope (SEM) was used to elucidate the critical organismal interaction at kernel (macro-) and microscopic levels. As kernel damage is the main entrance for fungal invasion, maize kernels with gradually aggravated damages from intact to pierced to halved kernels with A. flavus were cultured for 0–120 h. The spectral fingerprints of the A. flavus-maize kernel complex over time were analyzed with principal components analysis (PCA) of hyperspectral images, where the pseudo-color score maps and the loading plots of the first three PCs were used to investigate the dynamic process of fungal infection and to capture the subtle changes in the complex with different hardness of the maize matrix. The dynamic growth process of A. flavus and the interactions of fungus-maize complexes were explained on a microscopic level using SEM. Specifically, fungus morphology, e.g., hyphae, conidia, and conidiophore (stipe) was accurately captured on the microscopic level, and the interaction process between A. flavus and nutrient loss from the maize kernel tissues (i.e., embryo, and endosperm) was described. Furthermore, the growth stage discrimination models based on PLSDA with the results of CCRC = 100 %, CCRV = 97 %, CCRIV = 93 %, and the prediction models of AFB1 based on PLSR with satisfactory performance (R2C = 0.96, R2V = 0.95, R2IV = 0.93 and RPD = 3.58) were both achieved. In conclusion, the results from both macro-level (Vis/NIR-HSI) and micro-level (SEM) assessments revealed the dynamic organismal interactions in A. flavus-maize kernel complex, and the detailed data could be used for modeling, and quantitative prediction of aflatoxin, which would establish a theoretical foundation for the early detection of fungal or toxin contaminated grains to ensure food security.

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.

Biofumigant potential and inhibition mechanism of Trichoderma asperelloides SKRU-01 volatile organic compounds for controlling aflatoxigenic Aspergillus parasiticus and Aspergillus flavus in stored peanuts

Microbial volatile organic compounds (VOCs) have emerged as promising alternatives to synthetic fungicides for managing stored grain. In this study, the inhibitory effects of Trichoderma asperelloides SKRU-01 VOCs on hyphal growth and spore germination of Aspergillus parasiticus TISTR 3276 and A. flavus PSRDC-4 were investigated. The results demonstrated significant suppression of hyphal growth and spore germination in both strains by SKRU-01 VOCs. By using solid-phase microextraction (SPME) coupled with gas chromatography-mass spectrometry (GC-MS), the SKRU-01 VOCs were identified to contain 23 compounds, with acetophenone being predominant (14.41%). Antifungal experiments revealed that acetophenone, at a minimum inhibitory concentration (MIC) of 1.0 μL/mL (solid media assay) or 1.0 μL/L (vapor phase assay), completely inhibited the growth of both strains. Moreover, the application of SKRU-01 VOCs effectively reduced mold density and aflatoxin B1 (AFB1) production in peanuts and also exhibited superior efficacy compared to acetophenone at a 1/2 MIC concentration. Acetophenone exhibited inhibitory effects on both fungal strains through multiple mechanisms of action. This included its ability to inhibit ergosterol biosynthesis, reduce the aflatoxin inducer methylglyoxal, impair antioxidant defense enzymes, and disrupt non-enzymatic defense molecules. Overall, this research highlights the biofumigant potential of SKRU-01 VOCs in stored grain management and provides novel insights into their antifungal mechanism against A. parasiticus and A. flavus. Furthermore, these findings contribute to the development of sustainable strategies for grain preservation and underscore the broader applications of microbial VOCs in agricultural and food safety practices.

Afla Toxin B&lt;SUB&gt;1&lt;/SUB&gt; in Fish Feeds and Experimental Acute Aflatoxicosis in an Air-Breathing Teleost

A general survey of three types of fish feeds for the incidence of toxigenic mold infestation revealed an alarming level of aflatoxigenic Aspergillus flavus contamination during storage. About 89% of A. flavus strains were toxigenic. The toxicity of crude toxin sample was assessed on Channa punctatuus. The experiment was conducted using pure crystalline aflatoxin B. Four different concentrations (10, 20, 30 and 40 mg/D) of pure toxin in 0.5 ml propylene glycol were administered intraperitoneally to four groups of fish along with a control. Observations were made on day 20, 40, 60 and 80. The treated fish showed loss of appetite, followed by listlessness and increased mucus over body surface. Hemorrhagic patches and tumors were prominent on liver. Histopathologically, liver was the most prominently affected organ leading to classical trabeular hepatoma. The excretory -kidney revealed some pre-neoplastic alteration arising from tubular epithelium. The head -kidney was atrophic, but proliferation of inter-renal lobules was prominent. The muscularis of the stomach showed severe proliferation. The intestine, pyloric caeca and gills were atrophic and necrosed. Formation of atypical glandular masses in mucosal region was marked in the intestine. The spleenic pulps were indistinguishable and showed a monotony of lymphocytes. The total and differential counts of leucocytes revealed a significant rise of lymphocytes in peripheral blood.

High-efficiency fungal pathogen intervention for seed protection: new utility of long-chain alkyl gallates as heat-sensitizing agents.

Control of food-contaminating fungi, especially pathogens that produce mycotoxins, is problematic since effective method for intervening fungal infection on food crops is often limited. Generally Regarded As Safe (GRAS) chemicals, such as natural compounds or their structural derivatives, can be developed as antimicrobial agents for sustainable food/crop production. This study identified that long-chain alkyl gallates, i.e., octyl-, nonyl-, and decyl gallates (OG (octyl 3,4,5-trihydroxybenzoic acid), NG, DG), can function as heat-sensitizing agents that effectively prevent fungal contamination. Out of twenty-eight candidate compounds and six conventional antifungal agents examined, the heat-sensitizing capacity was unique to the long-chain alkyl gallates, where OG exhibited the highest activity, followed by DG and NG. Since OG is a GRAS compound classified by the United States Food and Drug Administration (FDA), further in vitro antifungal studies were performed using OG. When OG and mild heat (57.5°C) were co-administered for 90 seconds, the treatment achieved > 99.999% fungal death (> 5 log reduction). Application of either treatment alone was significantly less effective at reducing fungal survival. Of note, co-application of OG (3 mM) and mild heat (50°C) for 20 minutes completely prevented the survival of aflatoxigenic Aspergillus flavus contaminating crop seeds (Brassica rapa Pekinensis), while seed germination rate was unaffected. Heat-sensitization was also determined in selected bacterial strains (Escherichia coli, Agrobacterium tumefaciens). Altogether, OG is an effective heat-sensitizing agent for control of microbial pathogens. OG-mediated heat sensitization will improve the efficacy of antimicrobial practices, achieving safe, rapid, and cost-effective pathogen control in agriculture/food industry settings.

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

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

Cocoa-associated filamentous fungi for the biocontrol of aflatoxigenic Aspergillus flavus.

Aflatoxin and other mycotoxin contamination are major threats to global food security and present an urgent need to secure the global food crop against spoilage by mycotoxigenic fungi. Cocoa material is noted for naturally low aflatoxin contamination. This study was designed to assess the potential for harnessing cocoa-associated filamentous fungi for the biocontrol of aflatoxigenic Aspergillus flavus. The candidate fungi were isolated from fermented cocoa beans collected from four cocoa-growing areas in Ghana. Molecular characterization included Internal Transcribed Spacer (ITS)-sequencing for identification and polymer chain reaction (PCR) to determine mating type. Effects of the candidate isolates on growth and aflatoxin-production by an aflatoxigenic A. flavus isolate (BANGA1) were assessed. Aflatoxin production was monitored by UV fluorescence and quantified by enzyme-linked immunosorbent assay (ELISA). Thirty-six filamentous fungi were cultured and identified as Aspergillus, Cladosporium, Lichtheimia, or Trichoderma spp. isolates. The isolates generally interacted negatively with BANGA1 growth and aflatoxin production. The Aspergillus niger and Aspergillus aculeatus biocontrol candidates showed the strongest colony antagonism (54%-94%) and reduction in aflatoxin production (12%-50%) on agar. In broth, the A. niger isolates reduced aflatoxin production by up to 97%. Metabolites from the A. niger isolates showed the strongest inhibition of growth by BANGA1 and inhibited aflatoxin production. Four of the candidate isolates belonged to the MAT1-1 mating type and 12 identified as MAT1-2. This may be indicative of the potential for genetic recombination events between fungi in the field, a finding which is particularly relevant to the risk posed by A. flavus biocontrol measures that rely on atoxigenic A. flavus strains.

ANTIFUNGAL ACTIVITY OF REUTERIN AGAINST AFLATOXIGENIC ASPERGILLUS FLAVUS

Reuterin is a secondary metabolite of the lactic acid bacteria Limosilactobacillus reuteri having broad antimicrobial activity. This study aimed to determine the antifungal activity of reuterin against aflatoxigenic Aspergillus flavus (A. flavus). The aflatoxigenic A. flavus BIO 33212 isolated from Indonesian nutmeg was used in this study. The minimum inhibitory concentration (MIC) of reuterin based on radial growth and colony-forming assays in solid and liquid fat-enriched media against A. flavus was determined. The effect of reuterin on the morphological structure of A. flavus was investigated by scanning electron microscopy (SEM). The aflatoxin B1 (AFB1) produced by A. flavus was evaluated by enzyme-linked immunosorbent assay. Reuterin effectively prolonged the lag phase and decreased the growth rate of A. flavus. At 2 and 4 mM, reuterin demonstrated radial growth inhibition by 5.59% and 35.40%, respectively, while the reductions in colony numbers were 18.36% and 69.51%, respectively. At higher concentrations (6 and 8 mM), the fungal growth was inhibited and reduced completely (100%). SEM revealed the disruption of hyphae and conidiophore development and conidial damage. However, a contradictory phenomenon was found when reuterin at &lt; 6 mM triggered a higher production of AFB1.

In vitro Evaluation of Rhizobacterial Strains from Groundnut on Growth of Aflatoxigenic Aspergillus Flavus

In vitro Evaluation of Rhizobacterial Strains from Groundnut on Growth of Aflatoxigenic Aspergillus Flavus

Molecular characterization of aflatoxigenic and non-aflatoxigenic Aspergillus flavus strains isolated from peanut sold in northern Togo

The contamination of agricultural products and aflatoxins synthesis can be controlled and reduced by the application of a biological control product based on atoxinogenic Aspergillus flavus strains. The purpose of this work was to select atoxinogenic Aspergillus flavus strains that can be used in the biological control of aflatoxins. Thirty-four (34) strains of Aspergillus flavus were used and the Nor-1, Ver-1, Omt-A and AflR genes involved in the aflatoxin biosynthesis pathway were sought. The growth speed and ability of atoxigenic strains to inhibit the growth of toxigenic strains were also determined. The results showed that 50% of the strains have at least one of the genes sought and the percentages of inhibition (PI) of the atoxinogenic strains varied significantly from 16.98% to 62.50% at the threshold of 5% according to the Tukey test (p-value = 0.0000136). The mycelial growth speed (VCM) of the atoxinogenic strains varied from 7.5 to 10 mm/day with an average VCM of 8.4 ± 0.05 mm/day. Strains AKA-10; AGA-8; AMAN-35; ABA-28 and AGA-46 were found to be more effective in inhibiting mycelial growth of toxigenic strains.

Characterization and Determination of Aflatoxigenic and Non-aflatoxigenic Aspergillus flavus Isolated from Bakery Food Products from Frontier around Davangere District

Mycotoxins are secondary metabolites produced by filamentous fungi in food and feed due to several conditions that affect fungal growth and mycotoxin production in different ways. Mycotoxin contamination in bakery food products is seriously dangerous to humans and animals. This study aimed to morphologically characterize and determine the aflatoxigenic and non-aflatoxigenic Aspergillus flavus isolates. Thirty three isolates of A.flavus were obtained from bakery food products collected from bakeries in rural areas like Bathi, Kodaganur, Bada, sasalu, Mayakonda, Avargere, Anaberu, Alur, Attigere, Echagatta around Davangere city. They were cultured on Potato Dextrose Agar medium (PDA), Rose Bengal Agar medium (RBA), Czapec(dox) agar medium (CZA) and Sabouraud’s dextrose agar medium (SDA). By observing the colony color and texture macromorphological characteristics were determined and micromorphological characteristics were determined by observing the spore color, size, structure, conidiophore structure, conidia, vesical shape under microscope. The production of aflatoxin was determined by UV fluorescence of isolates on coconut cream agar (CCA) medium plates. In aflatoxin detection 20 (60.60%) isolates of A.flavus shows positive results and 13 (39.39%) isolates of A.flavus shows negative results. The highest incidence of A.flavus was recorded in samples collected from Attigere followed by Bathi, Alur, Echagatta, Kodaganur, Bada, Anaberu, Sasalu, Mayakonda, Avargere. The incidence of A.flavus that produces aflatoxin highlights the necessity of taking action to eliminate their presence in food. The non-aflatoxigenic strains are being used in a biological control strategy to outcompete the aflatoxigenic ones.

土壌サンプル中のアフラトキシン産生菌の生残を調査するための寒天培地全量抽出法

In this study, we investigated a method of extracting the whole agar dish culture to assess the existence and survival of producing fungi of aflatoxins (AFs) in field soil samples. In a control experiment using a known aflatoxigenic Aspergillus flavus strain with dichlorvos (DV) - coated agar or DV-free agar, no significant difference on the recovery of colony numbers was observed while DV clearly inhibited AFs accumulation. Therefore, a method of extracting the whole dish culture of DV-free agar followed by aflatoxin B1 (AFB1) analysis was applied to assess the survival of aflatoxigenic fungi in soil samples during storage. Soil samples stored at different temperature (4°C, -20°C, and -80°C) and duration (3-12 months) were cultured and analyzed for the accumulation of AFB1 in triplicate. Each soil sample suspension was cultured on DV-free agar for 7 days at 25°C, and the whole dish culture was extracted by methanol and the amount of AFB1 was measured. AFB1 amounts were drastically decreased after the fourth month of storage at all temperatures tested. After the fifth month, AFB1 amounts of samples stored at 4°C were significantly lower than those stored at -20°C or -80°C, indicating that temperatures below -20°C may be suitable for longer storage of soil samples. This whole dish culture extraction method is easy to handle and will be applicable to estimate the population of aflatoxigenic fungi among various soil samples from different origin or conditions.

Root-associated bacteria Bacillus albus and Bacillus proteolyticus promote the growth of peanut seedlings and protect them from the aflatoxigenic Aspergillus flavus CDP2

Three isolates of bacteria NNK24, NDP61, and 0405-02, obtained from the surface and the inside of healthy peanut roots, were considered putative epiphytic and endophytic bacteria of peanut plants. 16S rRNA gene sequencing and BLAST search revealed that NNK24, NDP61 belong to Bacillus albus species and 0405-02 belong to Bacillus proteolyticus species. The culture broths of all 3 isolates obtained in the stationary phase showed good antifungal activity, approximately 70%–80% in the in-vitro antagonistic test. Meanwhile, in the in-vivo assay, after 72-hr-incubation of peanut seeds with Aspergillus flavus CDP2 conidia, isolates NNK24 and NDP61 reduced the mold growth from 6.9 log (cfu/g) to 4.5 and 3.9 log (cfu/g), respectively; whereas strain 0405-02 had only a slighter effect on the mold growth. Soaking peanut seeds in bacterial culture broth at 107 cfu/ml for 30 min promoted well seedling growth with the Vigour index (VI) increasing by about 3.6–5.3 times; reduced the Disease severity index (DSI) from 0.59 to 0.18–0.28. At 30 days after planting (DAP) seedlings into the soil, the plant weight and plant length grew approximately by 1.5–1.9 times and 1.4–1.6 times, respectively. Therefore, Bacillus albus NNK24, NDP61 and Bacillus proteolyticus 0405-02 are good candidates for microbial inoculants to promote peanut plant growth and protect them from aflatoxigenic Aspergillus flavus growth in order to develop sustainable agriculture.

The Effect of Cultivation Conditions on Antifungal and Maize Seed Germination Activity of Bacillus-Based Biocontrol Agent.

Aflatoxin contamination is a global risk and a concerning problem threatening food safety. The biotechnological answer lies in the production of biocontrol agents that are effective against aflatoxins producers. In addition to their biocontrol effect, microbial-based products are recognized as efficient biosolutions for plant nutrition and growth promotion. The present study addresses the characterization of the representative of Phaseolus vulgaris rhizosphere microbiome, Bacillus sp. BioSol021, regarding plant growth promotion traits, including the activity of protease, cellulase, xylanase, and pectinase with the enzymatic activity index values 1.06, 2.04, 2.41, and 3.51, respectively. The potential for the wider commercialization of this kind of product is determined by the possibility of developing a scalable bioprocess solution suitable for technology transfer to an industrial scale. Therefore, the study addresses one of the most challenging steps in bioprocess development, including the production scale-up from the Erlenmeyer flask to the laboratory bioreactor. The results indicated the influence of the key bioprocess parameters on the dual mechanism of action of biocontrol effects against the aflatoxigenic Aspergillus flavus, as well on maize seed germination activity, pointing out the positive impact of high aeration intensity and agitation rate, resulting in inhibition zone diameters of 60 mm, a root length 96 mm, and a shoot length 27 mm.

Plant-based natural flavonoids show strong inhibition of aflatoxin production and related gene expressions correlated with chemical structure

Aflatoxins are strong carcinogenic and mutagenic fungal metabolites, and aflatoxin contamination is a critical issue in agriculture and food production. Natural flavonoids can suppress aflatoxin biosynthesis; however, the structure–activity relationship remains unclear. In the present study, a total of 36 structurally related natural flavonoids were tested against the aflatoxigenic Aspergillus flavus, both in-vitro and in-situ (on maize kernels), to investigate their structure–activity relationship and biological activity. Aflatoxin production (IC50 values: 10.85–20.09 μg/mL) and the expression of related genes (aflD, aflK, aflQ, and aflR) were found to be strongly inhibited. Structure–activity relationship studies revealed that the [–OH] or [–O–CH3] groups at position 6 of ring A and position 4′ of ring B were closely associated with antifungal and antiaflatoxigenic activities. These findings provide valuable information for the development of clean and safe methods to prevent aflatoxin contamination in food.

Bioprotection of Zea mays L. from aflatoxigenic Aspergillus flavus by Loigolactobacillus coryniformis BCH-4.

Fungal infection causes deterioration, discoloration, and loss of nutritional values of food products. The use of lactic acid bacteria has diverse applications in agriculture to combat pathogens and to improve the nutritional values of cereal grains. The current research evaluated the potential of Loigolactobacillus coryniformis BCH-4 against aflatoxins producing toxigenic Aspergillus flavus strain. The cell free supernatant (CFS) of Loig. coryniformis was used for the protection of Zea mays L. treated with A. flavus. No fungal growth was observed even after seven days. The FT-IR spectrum of untreated (T1: without any treatment) and treated maize grains (T2: MRS broth + A. flavus; T3: CFS + A. flavus) showed variations in peak intensities of functional group regions of lipids, proteins, and carbohydrates. Total phenolics, flavonoid contents, and antioxidant activity of T3 were significantly improved in comparison with T1 and T2. Aflatoxins were not found in T3 while observed in T2 (AFB1 and AFB2 = 487 and 16 ng/g each). HPLC analysis of CFS showed the presence of chlorogenic acid, p-coumaric acid, 4-hydroxybenzoic acid, caffeic acid, sinapic acid, salicylic acid, and benzoic acid. The presence of these acids in the CFS of Loig. coryniformis cumulatively increased the antioxidant contents and activity of T3 treated maize grains. Besides, CFS of Loig. coryniformis was passed through various treatments (heat, neutral pH, proteolytic enzymes and catalase), to observe its stability. It suggested that the inhibitory potential of CFS against A. flavus was due to the presence of organic acids, proteinaceous compounds and hydrogen peroxide. Conclusively, Loig. coryniformis BCH-4 could be used as a good bioprotecting agent for Zea mays L. by improving its nutritional and antioxidant contents.

Water safety, antifungal-resistant aflatoxigenic aspergillus flavus and other pathogenic fungi in a community hand-dug wells.

To investigate hand-dug well water used for drinking and domestic purposes in a rural community in Southwest Nigeria for water safety and fungal presence as well as to determine the antifungal resistance and aflatoxigenic potentials of isolated fungi. Water samples were analysed for risk of contamination, bacteriological and mycological parameters using a standard sanitary survey checklist and microbiological culturing. Isolates were identified and subjected to antifungal resistance profiling using the diffusion method for susceptibility testing of filamentous fungi. Multidrug-resistant strains were confirmed with DNA barcoding identification. Fungal isolates were screened for aflatoxigenic potentials by culture methods and confirmed by densitometric analysis. From the 23 hand-dug wells assessed, 56.52% had a high risk of contamination (ROC) score, nitrate >50 mg/L (73.9%), and the presence of total coliforms (100%), Escherichia coli (43.48%) and fungi (91.3%). Spearman rank correlation coefficient gave a positive and strong correlation between Total Fungi and Faecal Coliform (r=0.701; p=0.016; n=23) at 0.05 significance level (2-tailed). Aspergillus sp. (34%), Penicillium sp. (18%) and Rhizopus sp. (17%) were the most dominant fungal genera. Isolates were resistant to fluconazole (76.19%), ketoconazole (73.80%), clotrimazole (92.86%), griseofulvin (88.09%) and nystatin (100%). Penicillium and Aspergillus (50%) were positive for cultural mycotoxin screening. A strain of antifungal-resistant A. flavus produced aflatoxin B1 (752 ppb) and B2 (15 ppb). The existence of antifungal-resistant and aflatoxigenic fungi in water used for drinking and domestic purposes shows that filamentous fungi constitute greater threats than previously recognized and this call for a paradigm shift from the perceived safety of untreated hand-dug well-water.