Aflatoxin B1 Contamination Research Articles

Simultaneous Degradation of AFB1 and ZEN by CotA Laccase from Bacillus subtilis ZJ-2019-1 in the Mediator-Assisted or Immobilization System.

The global prevalence of aflatoxin B1 (AFB1) and zearalenone (ZEN) contamination in food and feed poses a serious health risk to humans and animals. Recently, enzymatic detoxification has received increasing attention, yet most enzymes are limited to degrading only one type of mycotoxin, and free enzymes often exhibit reduced stability and activity, limiting their practicality in real-world applications. In this study, the laccase CotA gene from ZEN/AFB1-degrading Bacillus subtilis ZJ-2019-1 was cloned and successfully expressed in Escherichia coli BL21, achieving a protein yield of 7.0 mg/g. The recombinant CotA (rCotA) completely degraded AFB1 and ZEN, with optimal activity at 70 °C and pH 7.0. After rCotA treatment, neither AFB1 nor ZEN showed significantly cytotoxicity to mouse macrophage cell lines. Additionally, the AFB1/ZEN degradation efficiency of rCotA was significantly enhanced by five natural redox mediators: acetosyringone, syringaldehyde, vanillin, matrine, and sophoridin. Among them, the acetosyringone-rCotA was the most effective mediator system, which could completely degrade 10 μg of AFB1 and ZEN within 1 h. Furthermore, the chitosan-immobilized rCotA system exhibited higher degradation activity than free rCotA. The immobilized rCotA degraded 27.95% of ZEN and 41.37% of AFB1 in contaminated maize meal within 12 h, and it still maintained more than 40% activity after 12 reuse cycles. These results suggest that media-assisted or immobilized enzyme systems not only boost degradation efficiency but also demonstrate remarkable reusability, offering promising strategies to enhance the degradation efficiency of rCotA for mycotoxin detoxification.

Rolling Circle Amplification-Enabled Ultrasensitive Point-of-Care Test Method for Aflatoxin B1 in the Environment and Food

Aflatoxin B1 (AFB1) contamination poses a fatal risk to human beings and urgently needs highly sensitive detection for environmental monitoring and food safety. However, the existing challenges are the unsatisfied sensitivity of the immunoassay methods and the complex matrix effect. Rolling circle amplification (RCA) is a promising method for nucleic acid isothermal amplification due to its high specificity and sensitivity. Herein, we constructed a general RCA-based point-of-care test method (RCA−POCT). With biotinylated antibodies, streptavidin, and biotinylated RCA primers, we realized the signal transduction and preliminary signal amplification. In this way, the fluorescent signal of the immunocomplex on the microwells was greatly enhanced. Under optimal conditions, we recorded sensitive detection limits for aflatoxin B1 (AFB1) of 1.94, 16.3, and 37.7 fg/mL (femtogram per microliter), and wide linear ranges with 5 × 10−6 to 5, 5 × 10−5 to 5, and 5 × 10−5 to 5 ng/mL in the irrigation water, field soil, and peanut samples, respectively. Satisfactory recovery, specificity, repeatability, and reproducibility were observed. The RCA−POCT was validated by comparing it to the HPLC method. This work provides a general RCA-assisted detection method for AFB1 in the environment and food.aflatoxin

Aflatoxin B1 in senna pods from field to storage in Tamil Nadu, India

ABSTRACT Senna, a medicinal herb, is highly susceptible to aflatoxin contamination, which often limits the export value of the final products due to the regulatory limits of importing countries. Presence of aflatoxin B1 (AFB1) was investigated in 229 senna pod samples at various stages from field to storage over three years. Higher incidence of AFB1 was revealed during the late harvest stage with a mean level of 52.4 µg/kg and a range of LOD-206 µg/kg. Out of 48 late harvest samples, 37 exceeded the AFFB1 limit of 2 µg/kg. In contrast, the majority of preharvest samples showed lower levels of AFB1 (1.0 µg/kg). During drying, increase in the mean AFB1 level to 4 µg/kg was observed and it could further increase to 18.1 μg/kg in storage. These results highlight the status of aflatoxin contamination in senna pods and emphasise the importance of implementing good agricultural practices in senna cultivation to mitigate AFB1 contamination.

Prevalence and Quantification of Aflatoxin B1 in Broiler Meat and Poultry Feed at Different Zones of Sindh, Pakistan

This study aimed to assess the prevalence and levels of aflatoxin B1 in broiler meat and feed samples from various zones of Sindh, Pakistan, conducted at Sindh Agriculture University, Tandojam, during 2022-2023. A total of 360 broiler meat and feed samples, with 120 from southern, central, and northern zones, were collected from retail shops and poultry farms. All samples were screened for aflatoxin B1 using the ELISA Bio-Shield Total Extra Sensitive Kit. Negative samples were spiked with 5 and 10g/kg aflatoxin B1 for validation. The southern zone had the highest contamination of aflatoxin B1 in broiler meat (58.33%; 36.50±2.08 µg/Kg) and feed (67.50%; 66.20±1.15 µg/Kg), followed by the central zone (40.00%; 32.60±1.64 µg/Kg) and the northern zone (25.00%; 20.90±2.82 µg/Kg). Contamination levels in feed samples were also higher in the southern zone compared to central (48.30%; 56.25±0.87µg/Kg) and northern (28.30%; 47.55±1.50 µg/Kg) zones. The aflatoxin B1 levels in both meat and feed samples exceeded the FDA-recommended limit of 20 µg/Kg, posing a significant risk to food safety. These findings highlight the urgent need for a monitoring plan to mitigate aflatoxin contamination in broiler meat, poultry products, and feedstuffs across Sindh, Pakistan, to ensure safer food production.

Effect of lactic acid bacteria inoculation on the aflatoxin B1 contamination and the diversity of yeast communities in Aspergillus flavus-contaminated experimental corn silage

AbstractThe present work aimed to study the yeast communities of whole crop corn silages (CS) that were previously contaminated with aflatoxin-producing Aspergillus flavus (CSCA). In addition, the effect of lactic acid bacterium (LAB) inoculation on the aflatoxin B1 (AFB1) content, genotoxicity, yeast load, and diversity of yeast communities were also investigated. In A. flavus contaminated silages, after two months, the AFB1 content was 40% lower with LAB inoculation, also a lower level of genotoxicity was determined. The number of yeasts cultured from the initial mixture of chopped whole crop corn was 4.8 × 107 CFU g−1 wet mass, while only 2.4 × 106 CFU g−1 from the CSCA and 7.1 × 105 CFU g−1 from the LAB-inoculated CSCA could be cultured. Based on 144 randomly isolated strains, the yeast community of the initial mixture consisted of 8 species. In contrast, the yeast community of CSCA consisted only of 4 species determined by 132 randomly selected isolates. LAB-inoculated CSCA consisted also of 4 species based on 158 randomly isolated strains. Saccharomyces cerevisiae and Pichia kudriavzevii proved to be predominant in the CSCA, while S. cerevisiae and Meyerozyma guilliermondii were the most abundant in the LAB-inoculated CSCA. The species richness was also confirmed by alpha diversity values (1.827, 1.188, and 1.123 as Shannon's indices for CS, CSCA, and LAB-inoculated CSCA, respectively). In response to LAB inoculation, the species diversity decreased considerably.

Aflatoxin B1 contamination in porridge formulations for children and ingredients sourced from selected markets in Rwanda

Providing safe and nutritious food for children globally is a challenge. In Rwanda, an initiative was introduced in 2018 to tackle chronic malnutrition by offering fortified porridge flour to economically disadvantaged families during critical periods. However, flour-based products in the sub-region have caused public health concerns following aflatoxin B1 (AFB1) contamination. This study analyzed the levels of AFB1 in 197 porridge formulations from health centers, and 248 samples of porridge ingredients from open markets in three districts of Rwanda. Samples were collected between June 2021 and December 2022 and analyzed using ultra-high-performance liquid chromatography. Of the 197 samples from health centers, 97.9 and 89.8% exceeded the European Union maximum limits for baby foods and foods for special medical purposes (0.1 μg/kg), and cereals and nuts (2 μg/kg), respectively with an average contamination level of 2.77 μg/kg (±0.98). Only four samples exceeded the East African Community maximum limits of 5 μg/kg for AFB1. Samples from open markets that exceeded the European Union and East African community limits of 0.1 μg/kg, 2 μg/kg, and 5 μg/kg ranged from 17 to 100%, 0 to 100%, and 0 to 100%, respectively. Site and processing significantly influenced levels of AFB1 contamination in open-market samples. The mean AFB1 levels were 17.85 μg/kg (±70.25) in Burera District, 36.04 μg/kg (±85.59) in Huye District, and 9.01 μg/kg (±18.49) in Nyarugenge District. The average AFB1 levels significantly varied between different products. Peanut samples showed higher contamination levels of 56.79 and 99.08 μg/kg for grain and flour, respectively. Flour samples in general had a higher mean of 51.65 μg/kg (±105.75), compared to grain samples, 16.5 μg/kg (±44). Thus, there are potential health risks associated with chronic exposure to AFB1 in children consuming flour-based foods from health centers and open markets. Interventions to mitigate AFB1 contamination and protect children should focus on food processing practices, implementing strict quality control measures, and raising awareness among stakeholders about the risks of AFB1 in flour-based products provided to children in Rwanda and similar settings. Key words: Flour-based porridge, contamination, aflatoxin B1, children, Rwanda

The preparation of immunomagnetic beads based on oriented Ab and its application for AFB1 enrichment

The escalating issue of Aflatoxin B1 (AFB1) contamination has posed an alarming concern worldwide. Enrichment efficiency is crucial to accurately detecting trace amounts of AFB1. Immunomagnetic beads (IMBs) enrichment is beneficial for reducing operation time and labor intensity. In this work, oriented MBs@PG@mAbs was prepared as novel IMBs while MBs@SA@mAbs and MBs@mAbs were prepared as traditional IMBs. At equivalent antibody coupling amounts, the normalized Fab orientation of MBs@PG@mAbs, MBs@SA@mAbs, and MBs@mAbs were 100, 70.7, and 68.0%, respectively. The MBs@PG@mAbs exhibit good AFB1 enrichment, with a maximum capture efficiency of 96.2%, and the capture efficiencies of MBs@SA@mAbs, and MBs@mAbs were 95.8 and 94.9%, respectively. The reliability and practicability of the proposed MBs@PG@mAbs for AFB1 enrichment were further evaluated using AFB1-spiked maize samples. The recoveries of MBs@PG@mAbs were 97.6, 95.0 and 94.2% when 2, 5 and 10 ng/g AFB1 were spiked in samples. The quantitative analysis results of the AFB1 in actual maize samples by MBs@PG@mAbs−ELISA and LC-MS/MS were consistent. Thus, the PG-mediated coupling method led to the most efficient enrichment performance and had the potential for further applications.

Characterization and genomic analysis of Bacillus megaterium with the ability to degrade aflatoxin B1.

Coix seed is a good product for both medicinal and food use, which is highly susceptible to aflatoxin B1 (AFB1) contamination during field transport, storage, and processing. The aim of this study is to find microbial strains that can solve the problem of contamination of coix seed. In this study, the AFB1-degrading microorganism SX1-1 was isolated and identified as a Bacillus megaterium based on morphology, microscopy, and 16S rDNA sequencing. The optimum culture conditions for SX1-1 to degrade AFB1 were determined to be 12 h. The optimum degradation conditions were 72 h, 57°C, and an initial pH of 8.0. The highest degradation of AFB1 was observed in the fermentation supernatant of the SX1-1 strain, with a degradation rate of 97.45%. In addition, whole-genome sequencing analysis of this strain revealed the presence of a number of enzymes that could potentially degrade AFB1. Importantly, SX1-1 was able to degrade AFB1-contaminated coix seed in situ by 50.06% after co-culture. In conclusion, this strain had a high AFB1 degradation ability, and has great potential and great application as a biocontrol agent for AFB1 degradation of coix seed.

Investigating the mechanism of Bacillus amyloliquefaciens YUAD7 degrading aflatoxin B1 in alfalfa silage using isotope tracing and nuclear magnetic resonance methods

BackgroundFungal toxins are highly toxic and widely distributed, presenting a considerable threat to global agricultural development. Addressing the issue of aflatoxin B1 (AFB1) contamination in feed, it is crucial to ascertain the effectiveness and mechanisms of microbial strains in degradation.ResultsThis study used isotope tracing and nuclear magnetic resonance (NMR) to investigate the degradation products of Bacillus amyloliquefaciens YUAD7 in complex substrates. By tracing 14C34-AFB1 and utilizing NMR, ultra-performance liquid chromatography–quadrupole time-of-flight/mass spectrometry (UPLC–Q-TOF/MS) purification and identification techniques, it was confirmed that AFB1 was degraded by YUAD7 into C12H14O4, C5H12N2O2, C10H14O2, and C4H12N2O, effectively removing 99.7% of AFB1 (100 μg/kg) from alfalfa silage. YUAD7 targeted the ester bond in the vanillin lactone ring structure, the ether bond in the furan ring structure, and the unsaturated carbon–carbon double bond in the furan ring structure during AFB1 degradation, disrupting the toxic sites responsible for AFB1's carcinogenic, teratogenic, and mutagenic effects and achieving biodegradation. Moreover, B. amyloliquefaciens YUAD7 transformed AFB1 through processes like hydrogenation, enzyme modification, and the loss of the -CO group while also being associated with metabolic pathways such as alanine, aspartate, glutamate metabolism, glutathione metabolism, cysteine and methionine metabolism, and pentose and glucuronate interconversions.ConclusionsThe utilization of isotope tracing allowed for rapid identification of degradation products in complex substrates, while NMR elucidated the structures of these products. This deepens our understanding of AFB1 biodegradation mechanisms, providing technical support for the practical application of these bacteria in degradation, and new insights into studying the biological degradation mechanism. B. amyloliquefaciens YUAD7 can be used as a potential strain for degrading AFB1 in large-scale silage.Graphical

Effects of aflatoxin B1 on subacute exposure of hybrid groupers (Epinephelus fuscoguttatus♀ × Epinephelus lanceolatus♂): Growth, liver histology, and integrated liver transcriptome and metabolome analysis

With the increasing incorporation of plant-based ingredients into the grouper diet, the issue of aflatoxin B1 (AFB1) contamination in the diet has become a significant concern. In this study, the negative effects of AFB1 on the growth and liver health of hybrid grouper (Epinephelus fuscoguttatus♀ × Epinephelus lanceolatus♂) were investigated in the context of growth, liver histology, serum biochemical indices, and integrated transcriptomic and metabolomic data. A total of 540 healthy hybrid groupers, initially weighing 11.59 ± 0.03 g, were randomly divided into six groups (three replicates of 30 fish each): the Control group was fed a basal diet, and the experimental groups were supplemented with 7 (AF7), 30 (AF30), 111 (AF111), 445 (AF445) and 2230 μg/kg AFB1 (AF2230) in the basal diet respectively, for 56 days. Groups Control, AF445, and AF2230 were selected for subsequent histological, muscle fatty acid, and transcriptomic and metabolomic analyses based on the results of hybrid grouper growth and serum biochemical indices. Compared to the Control group, both whole-body crude lipid and muscle crude lipid contents showed significant decreases in the AF2230 group (P < 0.05), while only muscle crude lipid content showed a significant decrease in the AF445 group (P = 0.001). Liver damage was seen in the histology of the liver of AF445 and AF2230 groups. Muscle fatty acid results showed that the addition of 445 and 2230 μg/kg AFB1 to the ration increased saturated fatty acids and monounsaturated fatty acids and decreased polyunsaturated fatty acids and highly unsaturated fatty acids in muscle (P < 0.05). Transcriptome analyses revealed multiple metabolic pathways associated with AFB1 metabolism, and metabolomics analyses further confirmed changes in the activity of these pathways. The results of the combined transcriptomic and metabolomic analyses indicated that AFB1 causes liver injury mainly by affecting liver retinol metabolism, metabolism of xenobiotics by cytochromes P450, drug metabolism-cytochromes P450 and biosynthesis of unsaturated fatty acids. In conclusion, dietary AFB1 levels above 445 μg/kg resulted in growth inhibition, liver injury, liver AFB1 accumulation, and reduced muscle polyunsaturated fatty acid content in grouper, thereby affecting muscle quality. This study provides novel insights into the detrimental effects of AFB1 on aquatic species and contributes to the scientific basis for the health and sustainability of aquaculture practices.

A label-free fluorescence sensing strategy based on gold nanoparticles assisted copper nanoclusters for the detection of aflatoxin B1 in cereals and peanuts

To effectively monitor the degree of aflatoxin B1 (AFB1) contamination in food and mitigate potential health risks to consumers eating food contaminated with AFB1, a label-free fluorescence aptamer-sensing strategy utilizing gold nanoparticles (AuNPs) was developed. Polyvinylpyrrolidone-copper nanoclusters (PVP-CuNCs) and AuNPs were selected as donor/acceptor pairs to convert the color signal change of AuNPs into fluorescence signal changes in PVP-CuNCs via the inner filter effect (IFE). In the presence of AFB1, the aptamer preferentially adsorbed with AFB1, and the AuNPs without aptamer protection changed color from red to blue under NaCl-induced aggregation. The green fluorescence of PVP-CuNCs recovered gradually. The developed strategy offers high sensitivity for the detection of AFB1, with a linear range of 0.02–20 μg L−1, and a low detection limit of 0.69 μg L−1. In addition, the strategy was successfully applied to real samples such as corn, rice, oats and peanuts, and the recovery rate was 93.4–106.2 %, which verified the reliability and applicability of this strategy. This strategy has the advantages of cost-effectiveness, high sensitivity, low detection limit and easy operation, providing a reference for sensitive and selective detection of mycotoxins contamination in food.

Beneficial effects of advanced chelate technology-based 7-minerals in aflatoxin-B1 challenged broilers: toxin residue reduction, serum biochemical improvement and modulation of the mRNA expression of NF-kB and Nrf2, and genes within their pathways.

Organic trace minerals (TM) offer superior nutritional benefits because of their stable structure, making their addition to broiler diets potentially beneficial during challenging periods such as aflatoxin B1 (AFB1) contamination. The present study evaluated the impacts of different replacement levels of inorganic TM (ITM) with advanced chelate technology-based TM (ACTM) on the growth performance, serum biochemical parameters, antioxidant indicators, and some inflammatory and immune parameters of broilers fed diets contaminated with AFB1. A 42-day experiment involved randomly assigning 1-day-old broiler chickens (n = 480) to one of five dietary treatments, each with six replicates. The treatments were as follows: (1) NC: basal diet without AFB1 and recommended ITM levels; (2) PC: basal diet with 0.5 mg kg-1 AFB1 and recommended ITM levels; (3) TB: PC diet +1 g kg-1 toxin binder; (4) ACTM50: replacement of ITM with 50% ACTM in the PC diet; and (5) ACTM100: replacement of ITM with 100% ACTM in the PC diet. Compared with PC treatment, ACTM100 treatment resulted in increased (P < 0.05) body weight gain, serum zinc and glutathione concentrations, immunoglobulin Y level, antioxidant enzyme activities, and hepatic gene expression of nuclear factor erythroid 2-related factor 2, glutathione peroxidase-1, superoxide dismutase-1 and transforming growth factor beta 1. The ACTM100 group also exhibited decreased AFB1 residue in the liver and kidney, serum alanine transaminase activity and malondialdehyde concentration, and hepatic gene expression levels of nuclear factor-kappa B and interferon-gamma (P < 0.05). These values were comparable to those recorded in the TB and NC treatments. In conclusion, completely replacing ITM with ACTM can benefit the metabolism and mitigate AFB1-induced immunotoxicity and oxidative damage in chickens by altering the mRNA expression of nuclear factor-kappa B and nuclear factor erythroid 2-related factor 2, and some genes downstream their signaling pathways. © 2024 Society of Chemical Industry.

Biological Detoxification of Aflatoxin B1 by Enterococcus faecium HB2-2.

Aflatoxin B1 (AFB1) contamination in food and feed is a global health and economic threat, necessitating the immediate development of effective strategies to mitigate its negative effects. This study focuses on the isolation and characterization of Enterococcus faecium HB2-2 (E. faecium HB2-2) as a potent AFB1-degrading microorganism, using morphological observation, biochemical profiling, and 16S rRNA sequence analysis. An incubation of E. faecium HB2-2 at 32 °C for 96 h in a pH 10 nutrient broth (NB) medium resulted in a remarkable degradation rate of 90.0% for AFB1. Furthermore, E. faecium HB2-2 demonstrated 82.9% AFB1 degradation rate in the peanut meal, reducing AFB1 levels from 105.1 to 17.9 μg/kg. The AFB1 degradation ability of E. faecium HB2-2 was found to be dependent on the fermentation supernatant. The products of AFB1 degradation by E. faecium HB2-2 were analyzed by liquid chromatography-mass spectrometry (LC-MS), and a possible degradation mechanism was proposed based on the identified degradation products. Additionally, cytotoxicity assays revealed a significant reduction in the toxicity of the degradation products compared to the parent AFB1. These findings highlight the potential of E. faecium HB2-2 as a safe and effective method for mitigating AFB1 contamination in food and feed.

Lactobacillus salivarius Ameliorates AFB1-induced hepatotoxicity via PINK1/Parkin-mediated mitophagy in Geese

Aflatoxin B1 (AFB1) is commonly found in feed ingredients and foods all over the world, posing a significant threat to food safety and public health in animals and humans. Lactobacillus salivarius (L. salivarius) was recorded to improve the intestinal health and performance of chickens. However, whether L. salivarius can alleviate AFB1-induced hepatotoxicity in geese was unknown. A total of 300 Lande geese were randomly assigned to five groups: control group, AFB1 low-dose group (L), L. salivarius+AFB1 low-dose group (LL), AFB1 high dosage groups (H), L. salivarius+AFB1 high dosage groups (LH), respectively. The results showed that the concentrations of ALT, AST, and GGT significantly increased after exposure to AFB1. Similarly, severe damage of hepatic morphology was observed including the hepatic structure injury and inflammatory cell infiltration. The oxidative stress was evidenced by the elevated concentrations of MDA, and decreased activities of GSH-Px, GSH and SOD. The observation of immunofluorescence, real-time PCR, and western blotting showed that the expression of PINK1 and the value of LC3II/LC3I were increased, but that of p62 significantly decreased after AFB1 exposure. Moreover, the supplementation of L. salivarius effectively improved the geese performance, ameliorated AFB1-induced oxidative stress, inhibited mitochondrial mitophagy and enhanced the liver restoration to normal level. The present study demonstrated that L. salivarius ameliorated AFB1-induced the hepatotoxicity by decreasing the oxidative stress, and regulating the expression of PINK1/Parkin-mediated mitophagy in the mitochondria of the geese liver. Furthermore, this investigation suggested that L. salivarius might serve as a novel and safe additive for preventing AFB1 contamination in poultry feed.

One stone two birds: Recycling of an agri-waste to synthesize laccase-immobilized hierarchically porous magnetic biochar for efficient degradation of aflatoxin B1 in aqueous solutions and corn oil

Aflatoxin B1 (AFB1) contamination of oils is a serious concern for the safety of edible oil consumers. Enzyme-assisted detoxification of AFB1 is an efficient and safe method for decontaminating oils, but pristine enzymes are unstable in oils and require modifications before use. Therefore, we designed a novel and magnetically separable laccase-carrying biocatalyst containing spent-mushroom-substrate (SMS)-derived biochar (BF). Laccase was immobilized on NH2-activated magnetic biochar (BF-NH2) through covalent crosslinking, which provided physicochemical stability to the immobilized enzyme. After 30 days of storage at 4 °C, the immobilized laccase (product named “BF-NH2-Lac”) retained ~95 % of its initial activity, while after five repeated cycles of ABTS oxidation, ~85 % activity retention was observed. BF-NH2-Lac was investigated for the oxidative degradation of AFB1, which exhibited superior performance compared to free laccase. Among many tested natural compounds as mediators, p-coumaric acid proved the most efficient in activating laccase for AFB1 degradation. BF-NH2-Lac demonstrated >90 % removal of AFB1 within 5.0 h, while the observed degradation efficiency in corn oil and buffer was comparable. An insight into the adsorptive and degradative removal of AFB1 revealed that AFB1 removal was governed mainly by degradation. The coexistence of multi-mycotoxins did not significantly affect the AFB1 degradation capability of BF-NH2-Lac. Investigation of the degradation products revealed the transformation of AFB1 into non-toxic AFQ1, while corn oil quality remained unaffected after BF-NH2-Lac treatment. Hence, this study holds practical importance for the research, knowledge-base and industrial application of newly proposed immobilized enzyme products.

Identification of a Novel Aflatoxin B1-Degrading Strain, Bacillus halotolerans DDC-4, and Its Response Mechanisms to Aflatoxin B1.

Aflatoxin B1 (AFB1) contamination is a food safety issue threatening human health globally. Biodegradation is an effective method for overcoming this problem, and many microorganisms have been identified as AFB1-degrading strains. However, the response mechanisms of these microbes to AFB1 remain unclear. More degrading enzymes, especially of new types, need to be discovered. In this study, a novel AFB1-degrading strain, DDC-4, was isolated using coumarin as the sole carbon source. This strain was identified as Bacillus halotolerans through physiological, biochemical, and molecular methods. The strain's degradation activity was predominantly attributable to thermostable extracellular proteins (degradation rate remained approximately 80% at 90 °C) and was augmented by Cu2+ (95.45% AFB1 was degraded at 48 h). Alpha/beta hydrolase (arylesterase) was selected as candidate AFB1-degrading enzymes for the first time as a gene encoding this enzyme was highly expressed in the presence of AFB1. Moreover, AFB1 inhibited many genes involved in the nucleotide synthesis of strain DDC-4, which is possibly the partial molecular mechanism of AFB1's toxicity to microorganisms. To survive under this stress, sporulation-related genes were induced in the strain. Altogether, our study identified a novel AFB1-degrading strain and explained its response mechanisms to AFB1, thereby providing new insights for AFB1 biodegradation.

Microalgae: A promising strategy for aflatoxin control in poultry feeds

Aflatoxins are toxic compounds produced by certain molds, primarily Aspergillus species, which can contaminate crops such as grains and nuts. These toxins pose a significant health risk to animals and humans. Aflatoxin B1 (AFB1) is the most potent of these compounds and has been well-characterized to lead to diminished growth and feed efficiency by disrupting nutrient absorption and metabolism in poultry. AFB1 can trigger apoptosis and inflammation, leading to a decline in immune function and changes in blood biochemistry in poultry. Recently, there has been growing interest in using microalgae as a natural antioxidant to mitigate the effects of aflatoxins in poultry diets. Microalgae have strong antioxidant, antimicrobial, anti-apoptotic, and anti-inflammatory properties, and adding them to aflatoxin-contaminated poultry diets has been shown to improve growth and overall health. This review investigates the potential of microalgae, such as Spirulina platensis, Chlorella vulgaris, and Enteromorpha prolifera, to mitigate AFB1 contamination in poultry feeds. These microalgae contain substantial amounts of bioactive compounds, including polysaccharides, peptides, vitamins, and pigments, which possess antioxidant, antimicrobial, and detoxifying properties. Microalgae can bind to aflatoxins and prevent their absorption in the gastrointestinal tract of poultry. They can also enhance the immune system of poultry, making them more resilient to the toxic effects of AFB1. Based on the data collected, microalgae have shown promising results in combating AFB1 contamination in poultry feeds. They can bind to aflatoxins, boost the immune system, and improve feed quality. This review emphasizes the harmful effects of AFB1 on poultry and the promising role of microalgae in reducing these effects.

Biotransformation of aflatoxin B1 by a novel strain Brevundimonas sp. LF-1

Aflatoxin B1 (AFB1) is a potent mycotoxin and a common source of food and feed contamination, posing risks to both human and animal health. The biotransformation of AFB1 has been proven to be a promising approach to control AFB1 contamination. In this study, Brevundimonas sp. LF-1 capable of degrading AFB1 was isolated from a corn-planted soil sample. Strain LF-1 could degrade 86.90% of 2 mg L−1 AFB1 after incubation in Luria-Bertani (LB) medium at 30 °C for 72 h and exhibited high performance when exposed to up to 10.0 mg L−1 AFB1. The optimum pH and temperature were 7.0–10.0 and 30 °C, respectively. The results of the in vitro cytotoxicity assay showed that the degradation products had considerably (p < 0.05) less harmful effects than the parent AFB1. Additionally, strain LF-1 possessed the bioremediation potential of AFB1 contamination for biocontrol strategies in animal fodder. Two putative novel AFB1-degrading enzymes, peroxiredoxin 1 and peroxiredoxin 2, were identified in the genome of strain LF-1. Comparative genomics indicated that the peroxiredoxin enzyme was widely distributed in the genus Brevundimonas. The comprehensive examination of strain LF-1 has outstanding potential for the development of detoxifying agents for AFB1 in the food and feed industries.

Chitosan nanoemulsion incorporated with Carum carvi essential oil as ecofriendly alternative for mitigation of aflatoxin B1 contamination in stored herbal raw materials

The present investigation entails the first report on entrapment of Carum carvi essential oil (CCEO) into chitosan polymer matrix for protection of stored herbal raw materials against fungal inhabitation and aflatoxin B1 (AFB1) production. Physico-chemical characterization of nanoencapsulated CCEO was performed through Fourier transform infrared spectroscopy, dynamic light scattering, X-ray diffractometry, and scanning electron microscopy. The nanoencapsulated CCEO displayed improved antifungal and AFB1 suppressing potentiality along with controlled delivery over unencapsulated CCEO. The encapsulated CCEO nanoemulsion obstructed the ergosterol production and escalated the efflux of cellular ions, thereby suggesting plasma membrane as prime target of antifungal action in Aspergillus flavus cells. The impairment in methyglyoxal production and modeling based carvone interaction with Afl-R protein validated the antiaflatoxigenic mechanism of action. In addition, CCEO displayed augmentation in antioxidant potentiality after encapsulation into chitosan nanomatrix. Moreover, the in-situ study demonstrated the effective protection of Withania somnifera root samples (model herbal raw material) against fungal infestation and AFB1 contamination along with prevention of lipid peroxidation. The acceptable organoleptic qualities of W. somnifera root samples and favorable safety profile in mice (animal model) strengthen the application of nanoencapsulated CCEO emulsion as nano-fungitoxicant for preservation of herbal raw materials against fungi and AFB1 mediated biodeterioration.

Screening and identification of an aflatoxin B1-degrading strain from the Qinghai-Tibet Plateau and biodegradation products analysis.

This research aimed to address the issue of aflatoxin B1 (AFB1) contamination, which posed severe health and economic consequences. This study involved exploring unique species resources in the Qinghai-Tibet Plateau, screening strains capable of degrading AFB1. UPLC-Q-Orbitrap HRMS and NMR were employed to examine the degradation process and identify the structure of the degradation products. Results showed that Bacillus amyloliquefaciens YUAD7, isolated from yak dung in the Qinghai-Tibet Plateau, removed 91.7% of AFB1 from TSB-AFB1 medium with an AFB1 concentration of 10 μg/mL (72 h, 37°C, pH 6.8) and over 85% of AFB1 from real food samples at 10 μg/g (72 h, 37°C), exhibiting strong AFB1 degradation activity. Bacillus amyloliquefaciens YUAD7's extracellular secretions played a major role in AFB1 degradation mediated and could still degrade AFB1 by 43.16% after boiling for 20 min. Moreover, B. amyloliquefaciens YUAD7 demonstrated the capability to decompose AFB1 through processes such as hydrogenation, enzyme modification, and the elimination of the -CO group, resulting in the formation of smaller non-toxic molecules. Identified products include C12H14O4, C5H12N2O2, C10H14O2, C4H12N2O, with a structure consisting of dimethoxyphenyl and enoic acid, dimethyl-amino and ethyl carbamate, polyunsaturated fatty acid, and aminomethyl. The results indicated that B. amyloliquefaciens YUAD7 could be a potentially valuable strain for industrial-scale biodegradation of AFB1 and providing technical support and new perspectives for research on biodegradation products.