Aflatoxin Detoxification Using Microorganisms and Enzymes

Adsorptive removal of aflatoxin B1 via spore protein from Aspergillus luchuensis YZ-1

Aflatoxin B1 (AFB1) is the most toxic mycotoxin commonly found in the environment. Finding efficient and environmentally friendly ways to remove AFB1 is critical. In this study, Aspergillus luchuensis YZ-1 demonstrated a potent ability to adsorb AFB1 for the first time, and the binding of AFB1 to YZ-1 is highly stable. Spores exhibited higher adsorption efficiency than mycelia, adsorbing approximately 95 % of AFB1 within 15 min. The spores were comprehensively characterized using scanning electron microscopy, transmission electron microscopy, energy-dispersive X-ray spectroscopy, and atomic force microscopy. Various adsorption kinetic models (pseudo-first and pseudo-second order), adsorption isotherm models (Freundlich and Langmuir), Fourier transform infrared, and X-ray photoelectron spectroscopy were used to investigate the adsorption properties and mechanisms. The adsorption capacity of spores decreased with heating, urea, and SDS treatments, indicating that spore proteins may be the primary substance for AFB1 adsorption. Subsequent experiments showed that proteins with molecular weights greater than 50 kDa played a key role in the adsorption. Additionally, the spores possess excellent storage properties and are valuable for adsorbing AFB1 from vegetable oils. Therefore, the YZ-1 spores hold promise for development into a novel biosorbent for AFB1 removal.

Aspirin suppresses hepatocellular carcinoma progression by inhibiting platelet activity

BACKGROUND

Hepatocellular carcinoma (HCC) is the most common malignant liver disease in the world. Platelets (PLTs) are known to play a key role in the maintenance of liver homeostasis and the pathophysiological processes of a variety of liver diseases. Aspirin is the most classic antiplatelet agent. However, the molecular mechanism of platelet action and whether aspirin can affect HCC progression by inhibiting platelet activity need further study.

AIM

To explore the impact of the antiplatelet effect of aspirin on the development of HCC.

METHODS

Platelet-rich plasma, platelet plasma, pure platelet, and platelet lysate were prepared, and a coculture model of PLTs and HCC cells was established. CCK-8 analysis, apoptosis analysis, Transwell analysis, and real-time polymerase chain reaction (RT-PCR) were used to analyze the effects of PLTs on the growth, metastasis, and inflammatory microenvironment of HCC. RT-PCR and Western blot were used to detect the effects of platelet activation on tumor-related signaling pathways. Aspirin was used to block the activation and aggregation of PLTs both in vitro and in vivo, and the effect of PLTs on the progression of HCC was detected.

RESULTS

PLTs significantly promoted the growth, invasion, epithelial-mesenchymal transition, and formation of an inflammatory microenvironment in HCC cells. Activated PLTs promoted HCC progression by activating the mitogen-activated protein kinase/protein kinase B/signal transducer and activator of transcription three (MAPK/ AKT/STAT3) signaling axis. Additionally, aspirin inhibited HCC progression in vitro and in vivo by inhibiting platelet activation.

CONCLUSION

PLTs play an important role in the pathogenesis of HCC, and aspirin can affect HCC progression by inhibiting platelet activity. These results suggest that antiplatelet therapy has promising application prospects in the treatment and combined treatment of HCC.

Aspirin suppresses hepatocellular carcinoma progression by inhibiting platelet activity

BACKGROUND

Hepatocellular carcinoma (HCC) is the most common malignant liver disease in the world. Platelets (PLTs) are known to play a key role in the maintenance of liver homeostasis and the pathophysiological processes of a variety of liver diseases. Aspirin is the most classic antiplatelet agent. However, the molecular mechanism of platelet action and whether aspirin can affect HCC progression by inhibiting platelet activity need further study.

AIM

To explore the impact of the antiplatelet effect of aspirin on the development of HCC.

METHODS

Platelet-rich plasma, platelet plasma, pure platelet, and platelet lysate were prepared, and a coculture model of PLTs and HCC cells was established. CCK-8 analysis, apoptosis analysis, Transwell analysis, and real-time polymerase chain reaction (RT-PCR) were used to analyze the effects of PLTs on the growth, metastasis, and inflammatory microenvironment of HCC. RT-PCR and Western blot were used to detect the effects of platelet activation on tumor-related signaling pathways. Aspirin was used to block the activation and aggregation of PLTs both in vitro and in vivo, and the effect of PLTs on the progression of HCC was detected.

RESULTS

PLTs significantly promoted the growth, invasion, epithelial-mesenchymal transition, and formation of an inflammatory microenvironment in HCC cells. Activated PLTs promoted HCC progression by activating the mitogen-activated protein kinase/protein kinase B/signal transducer and activator of transcription three (MAPK/ AKT/STAT3) signaling axis. Additionally, aspirin inhibited HCC progression in vitro and in vivo by inhibiting platelet activation.

CONCLUSION

PLTs play an important role in the pathogenesis of HCC, and aspirin can affect HCC progression by inhibiting platelet activity. These results suggest that antiplatelet therapy has promising application prospects in the treatment and combined treatment of HCC.

Rice Weevil (Sitophilus oryzae L.) Gut Bacteria Inhibit Growth of Aspergillus flavus and Degrade Aflatoxin B1

In this study, bacteria residing in the gut of the rice weevils (Sitophilus oryzae L.) (Coleoptera: Curculionidae) feeding on aflatoxin-contaminated corn kernels were isolated and evaluated for their ability to suppress Aspergillus flavus and to remove/degrade aflatoxin B1 (AFB1). Four morphologically distinct S. oryzae gut-associated bacterial isolates were isolated and identified as Bacillus subtilis (RWGB1), Bacillus oceanisediminis (RWGB2), Bacillus firmus (RWGB3), and Pseudomonas aeruginosa (RWGB4) based on 16S rRNA gene sequence analysis. These bacterial isolates inhibited A. flavus growth in the dual culture assay and induced morphological deformities in the fungal hyphae, as confirmed by scanning electron microscopy. All four bacterial isolates were capable of removing AFB1 from the nutrient broth medium. In addition, culture supernatants of these bacterial isolates degraded AFB1, and the degradation of toxin molecules was confirmed by liquid chromatography-mass spectrometry. The bacterial isolates, B. subtilis RWGB1, B. oceanisediminis RWGB2, and P. aeruginosa RWGB4, were capable of producing antifungal volatile organic compounds that inhibited A. flavus growth. These results suggest that the bacterial isolates from S. oryzae gut have the potential to bind and/or degrade AFB1. Further research on their application in the food and feed industries could enhance the safety of food and feed production.

The mitigative role of novel aflatoxin-degrading enzymes in diverse broiler performance indicators and gut microbiota following the consumption of diets contaminated with aflatoxins

BACKGROUND

This study aims to explore both the toxic effects of aflatoxins (AFs) and the protective effects of degrading enzymes (DE) on broilers exposed to AFs.

RESULTS

The findings reveal that a diet contaminated with 69.15 μg kg-1 of aflatoxin B1 had significant adverse effects on broilers. Specifically, it led to a reduction in average daily gain, dressed yield percentage, half-eviscerated yield with giblet yield percentage, eviscerated yield percentage, as well as serum superoxide dismutase (SOD), glutathione peroxidase activity and liver SOD activity (P < 0.05). Conversely, the diet increased the feed conversion ratio, liver index, serum glutamic oxaloacetic transaminase levels and malondialdehyde levels in both serum and liver (P < 0.05). Additionally, AFs disrupted the intestinal microflora significantly (P < 0.05), altering the relative abundance of Enterococcus, Lactobacillus and Escherichia in broiler jejunum. The addition of DE to AF-contaminated feed mitigated these negative effects and reduced the residues of aflatoxin B1, aflatoxin B2 and aflatoxin M1 in the liver and duodenum (P < 0.05). We also observed that broilers fed the diet pelleted at 80 °C exhibited improved dressing percentage and water holding capacity compared to those on the 75 °C diet.

CONCLUSION

In summary, DE serves as an effective feed additive for mitigating AF contamination in poultry production. © 2024 Society of Chemical Industry.

AflaILVB/G/I and AflaILVD are involved in mycelial production, aflatoxin biosynthesis, and fungal virulence in Aspergillus flavus

Aflatoxins (AFs) are produced by fungi such as Aspergillus flavus and A. parasiticus and are one of the most toxic mycotoxins found in agricultural products and food. Aflatoxin contamination, which requires the control of A. flavus, remains problematic because of the lack of effective strategies and the exploration of new compounds that can inhibit A. flavus growth and mycotoxin production is urgently required to alleviate potential deleterious effects. Acetohydroxy acid synthase (AHAS) and dihydroxy acid dehydratase are important enzymes in the biosynthetic pathways of branched-chain amino acids (BCAAs), including isoleucine, leucine, and valine. Enzymes involved in BCAA biosynthesis are present in bacteria, plants, and fungi, but not in mammals, and are therefore, attractive targets for antimicrobial and herbicide development. In this study, we characterized AflaILVB/G/I and AflaILVD, which encode the catalytic and regulatory subunits of AHAS and dihydroxy acid dehydratase, from the pathogenic fungus Aspergillus flavus. The AflaILVB/G/I and AflaILVD deletion mutant grew slower and produced smaller colonies than the wild-type strain when grown on glucose minimal medium, potato dextrose agar, and yeast extract medium for three days at 28°C, and disruption of AflaILVB/G/I caused a significant reduction in conidia production when grown on all kinds of media. Cellular stress assays determined that all strains were sensitive to H2O2. Importantly, the pathogenicity and aflatoxin production were affected when AflaILVB/G/I and AflaILVD were knocked out, particularly AflaILVB/G/I. A series of genes that encoded enzymes involved in aflatoxin synthesis were downregulated, meaning that the knockout of AflaILVB/G/I influenced aflatoxin synthesis in A. flavus strain WT. Collectively, our results demonstrate the potential value of antifungals targeting AflaILVB/G/I in A. flavus.

Characterization and mechanism of simultaneous degradation of aflatoxin B1 and zearalenone by an edible fungus of Agrocybe cylindracea GC-Ac2

Contamination with multiple mycotoxins is a major issue for global food safety and trade. This study focused on the degradation of aflatoxin B1 (AFB1) and zearalenone (ZEN) by 8 types of edible fungi belonging to 6 species, inclulding Agaricus bisporus, Agrocybe cylindracea, Cyclocybe cylindracea, Cyclocybe aegerita, Hypsizygus marmoreus and Lentinula edodes. Among these fungi, Agrocybe cylindracea strain GC-Ac2 was shown to be the most efficient in the degradation of AFB1 and ZEN. Under optimal degradation conditions (pH 6.0 and 37.4°C for 37.9 h), the degradation rate of both AFB1 and ZEN reached over 96%. Through the analysis of functional detoxification components, it was found that the removal of AFB1 and ZEN was primarily degraded by the culture supernatant of the fungus. The culture supernatant exhibited a maximum manganese peroxidase (MnP) activity of 2.37 U/mL. Interestingly, Agrocybe cylindracea strain GC-Ac2 also showed the capability to degrade other mycotoxins in laboratory-scale mushroom substrates, including 15A-deoxynivalenol, fumonisin B1, B2, B3, T-2 toxin, ochratoxin A, and sterigmatocystin. The mechanism of degradation of these mycotoxins was speculated to be catalyzed by a complex enzyme system, which include MnP and other ligninolytic enzymes. It is worth noting that Agrocybe cylindracea can degrade multiple mycotoxins and produce MnP, which is a novel and significant discovery. These results suggest that this candidate strain and its enzyme system are expected to become valuable biomaterials for the simultaneous degradation of multiple mycotoxins.

Beyond probiotics: Exploring the potential of postbiotics and parabiotics in veterinary medicine

Postbiotics and parabiotics (PP) are emerging fields of study in animal nutrition, preventive veterinary medicine, and animal production. Postbiotics are bioactive compounds produced by beneficial microorganisms during the fermentation of a substrate, while parabiotics are inactivated beneficial microbial cells, either intact or broken. Unlike probiotics, which are live microorganisms, PP are produced from a fermentation process without live cells and show significant advantages in promoting animal health owing to their distinctive stability, safety, and functional diversity. PP have numerous beneficial effects on animal health, such as enhancing growth performance, improving the immune system and microbiota of the gastrointestinal tract, aiding ulcer healing, and preventing pathogenic microorganisms from colonizing in the skin. Moreover, PP have been identified as a potential alternative to traditional antibiotics in veterinary medicine due to their ability to improve animal health without the risk of antimicrobial resistance. This review comprehensively explores the current research and applications of PP in veterinary medicine. We aimed to thoroughly examine the mechanisms of action, benefits, and potential applications of PP in various species, emphasizing their use specifically in livestock and poultry. Additionally, we discuss the various routes of administration to animals, including feed, drinking water, and topical use. This review also presents in-depth information on the methodology behind the preparation of PP, outlining the criteria employed to select appropriate microorganisms, and highlighting the challenges commonly associated with PP utilization in veterinary medicine.

Mitigating Aflatoxin B1-Induced Growth Impairment and Hepatic Stress in Nile Tilapia (Oreochromis niloticus): Comparative Efficacy of Saccharomyces cerevisiae and Silicate-Based Detoxifiers

The objective of this study was to detect the effects of acute aflatoxin B1 (AFB1) exposure in Nile tilapia (Oreochromis niloticus) and the effectiveness of Saccharomyces cerevisiae and silicate in reducing these effects. Two hundred and forty Nile tilapia fingerlings (16 ± 0.5 g) were randomly assigned to four experimental groups, each with 60 fish and three replicates. Control basal diet (Diet 1) and three test diets were formulated, where Diet 2 was supplemented with 200 ppb AFB1. Diets 3 and 4 were intoxicated with AFB1 (200 ppb) and supplemented with 0.5% S. cerevisiae or 0.5%, respectively. After 60 days, Diet 1 had considerably greater growth characteristics than the other groups (p < 0.05). Diet 2 revealed a reduced (p < 0.05) survival rate after 1 month of exposure. In addition, Diet 1 showed higher (p < 0.05) total protein and albumin levels than Diets 3 and 4. AFB1 residues were detected in the liver in fish-fed Diet 2, Diet 4, and Diet 3. Alanine aminotransferase, aspartate aminotransferase, creatinine, and urea levels increased (p < 0.05) in fish-fed Diet 2. The glutathione peroxidase, lysozyme, and catalase activity were decreased (p < 0.05) in the fish-fed Diet 2. The malondialdehyde level was significantly higher in fish given Diet 2 (p < 0.05) than in fish-fed Diets 3 and 4. Histopathological investigation of fish-fed Diet 2 revealed impaired liver and spleen; however, both treatments (Diets 3 and 4) successfully lowered inflammation and preserved liver and spleen integrities. In conclusion, AFB1 impaired growth performance and posed a severe health risk to Nile tilapia. Furthermore, S. cerevisiae alleviated the contamination of AFB1 effects more efficiently than silicate employed for toxin adsorption.

Some relevant mitigating agents of chronic aflatoxin exposure: a treatise

Aflatoxins, a group of toxic secondary metabolites produced by Aspergillus species, pose significant threats to human health due to their potent carcinogenic, mutagenic, and immunosuppressive properties. Chronic exposure to these contaminants, commonly found in staple foods such as maize and groundnuts, has been linked to an increased risk of liver cancer, growth impairment, and immune dysfunction. Several agents, such as calcium montmorillonite clay and Lactobacillus rhamnosus GG, have shown promise in reducing aflatoxin bioavailability and alleviating its toxic effects. Additionally, dietary supplements such as chlorophyllin, selenium, and N-acetylcysteine have demonstrated potential as adjuvants to counteract aflatoxin-induced oxidative stress and support liver function. In this treatise, some of the most discussed approaches to mitigating aflatoxin effects are explored in terms of their efficacy, safety, and potential mechanisms of action, which include direct aflatoxin binding, detoxification, cellular antioxidative, and hepatocellular protection properties. However, the effectiveness of these strategies can be influenced by various factors, such as dose, duration of exposure, and individual susceptibility. Therefore, further research is needed to optimize these interventions and develop new, targeted therapies for the prevention and treatment of aflatoxin-related diseases. This review aims to provide a comprehensive analysis of 18 pharmaceutical, nutraceutical, supplement, and probiotic strategies currently available for mitigating the deleterious effects of chronic aflatoxin exposure in humans and animal models.

Mechanisms by which microbial enzymes degrade four mycotoxins and application in animal production: A review

Mycotoxins are toxic compounds that pose a serious threat to animal health and food safety. Therefore, there is an urgent need for safe and efficient methods of detoxifying mycotoxins. As biotechnology has continued to develop, methods involving biological enzymes have shown great promise. Biological enzymatic methods, which can fundamentally destroy the structures of mycotoxins and produce degradation products whose toxicity is greatly reduced, are generally more specific, efficient, and environmentally friendly. Mycotoxin-degrading enzymes can thus facilitate the safe and effective detoxification of mycotoxins which gives them a huge advantage over other methods. This article summarizes the newly discovered degrading enzymes that can degrade four common mycotoxins (aflatoxins, zearalenone, deoxynivalenol, and ochratoxin A) in the past five years, and reveals the degradation mechanism of degrading enzymes on four mycotoxins, as well as their positive effects on animal production. This review will provide a theoretical basis for the safe treatment of mycotoxins by using biological enzyme technology.

Recombinant Oxidase from Armillaria tabescens as a Potential Tool for Aflatoxin B1 Degradation in Contaminated Cereal Grain

Forage grain contamination with aflatoxin B1 (AFB1) is a global problem, so its detoxification with the aim of providing feed safety and cost-efficiency is still a relevant issue. AFB1 degradation by microbial enzymes is considered to be a promising detoxification approach. In this study, we modified an previously developed Pichia pastoris GS115 expression system using a chimeric signal peptide to obtain a new recombinant producer of extracellular AFB1 oxidase (AFO) from Armillaria tabescens (the yield of 0.3 g/L), purified AFO, and selected optimal conditions for AFO-induced AFB1 removal from model solutions. After a 72 h exposure of the AFB1 solution to AFO at pH 6.0 and 30 °C, 80% of the AFB1 was degraded. Treatments with AFO also significantly reduced the AFB1 content in wheat and corn grain inoculated with Aspergillus flavus. In grain samples contaminated with several dozen micrograms of AFB1 per kg, a 48 h exposure to AFO resulted in at least double the reduction in grain contamination compared to the control, while the same treatment of more significantly (~mg/kg) AFB1-polluted samples reduced their contamination by ~40%. These findings prove the potential of the tested AFO for cereal grain decontamination and suggest that additional studies to stabilize AFO and improve its AFB1-degrading efficacy are required.

A New Benzaldehyde Derivative Exhibits Antiaflatoxigenic Activity against Aspergillus flavus

Aflatoxin B1 (AFB1) is the most potent naturally occurring carcinogen for humans and animals produced by the common fungus Aspergillus flavus (A. flavus). Aflatoxin (AF) contamination in commodities is a global concern related to the safety of food and feed, and it also impacts the agricultural economy. In this study, we investigated the AFB1-inhibiting activity of a new benzaldehyde derivative, 2-[(2-methylpyridin-3-yl)oxy]benzaldehyde (MPOBA), on A. flavus. It was found that MPOBA inhibited the production of AFB1 by A. flavus, with an IC50 value of 0.55 mM. Moreover, the inhibition of conidiation was also observed at the same concentration. The addition of MPOBA resulted in decreased transcript levels of the aflR gene, which encodes a key regulatory protein for the biosynthesis of AF, and also decreased transcript levels of the global regulator genes veA and laeA. These results suggested that MPOBA has an effect on the regulatory mechanism of the development and differentiation of conidia, leading to the inhibition of AFB1 production. In addition, the cytotoxicity study showed that MPOBA had a very low cytotoxic effect on the Madin-Darby canine kidney (MDCK) cell line. Therefore, MPOBA may be a potential compound for developing practically effective agents to control AF contamination.

The intestinal microbiota as mediators between dietary contaminants and host health

The gut microbiota sit at an important interface between the host and the environment, and are exposed to a multitude of nutritive and non-nutritive substances. These microbiota are critical to maintaining host health, but their supportive roles may be compromised in response to endogenous compounds. Numerous non-nutritive substances are introduced through contaminated foods, with three common groups of contaminants being bisphenols, phthalates, and mycotoxins. The former contaminants are commonly introduced through food and/or beverages packaged in plastic, while mycotoxins contaminate various crops used to feed livestock and humans alike. Each group of contaminants have been shown to shift microbial communities following exposure; however, specific patterns in microbial responses have yet to be identified, and little is known about the capacity of the microbiota to metabolize these contaminants. This review characterizes the state of existing research related to gut microbial responses to and biotransformation of bisphenols, phthalates, and mycotoxins. Collectively, we highlight the need to identify consistent, contaminant-specific responses in microbial shifts, whether these community alterations are a result of contaminant effects on the host or microbiota directly, and to identify the extent of contaminant biotransformation by microbiota, including if these transformations occur in physiologically relevant contexts.

Aflatoxins Contamination in Feed Commodities: From Occurrence and Toxicity to Recent Advances in Analytical Methods and Detoxification

Synthesized by the secondary metabolic pathway in Aspergilli, aflatoxins (AFs) cause economic and health issues and are culpable for serious harmful health and economic matters affecting consumers and global farmers. Consequently, the detection and quantification of AFs in foods/feeds are paramount from food safety and security angles. Nowadays, incessant attempts to develop sensitive and rapid approaches for AFs identification and quantification have been investigated, worldwide regulations have been established, and the safety of degrading enzymes and reaction products formed in the AF degradation process has been explored. Here, occurrences in feed commodities, innovative methods advanced for AFs detection, regulations, preventive strategies, biological detoxification, removal, and degradation methods were deeply reviewed and presented. This paper showed a state-of-the-art and comprehensive review of the recent progress on AF contamination in feed matrices with the intention of inspiring interests in both academia and industry.

The epigenetic regulator Set9 harmonizes fungal development, secondary metabolism, and colonization capacity of Aspergillus flavus

As a widely distributed food-borne pathogenic fungus, Aspergillus flavus and its secondary metabolites, mainly aflatoxin B1 (AFB1), pose a great danger to humans. It is urgent to reveal the complex regulatory network of toxigenic and virulence of this fungus. The bio-function of Set9, a SET-domain-containing histone methyltransferase, is still unknown in A. flavus. By genetic engineering means, this study revealed that, through catalyzing H4K20me2 and -me3, Set9 is involved in fungal growth, reproduction, and mycotoxin production via the orthodox regulation pathway, and regulates fungal colonization on crop kernels through adjusting fungal sensitivity reactions to oxidation stress and cell wall integrity stress. Further domain deletion and point mutation inferred that the SET domain is the core element in catalyzing H4K20 methylation, and D200 site of the domain is the key amino acid in the active center of the methyltransferase. Combined with RNA-seq analysis, this study revealed that Set9 regulates the aflatoxin gene cluster by the AflR-like protein (ALP), other than traditional AflR. This study revealed the epigenetic regulation mechanism of fungal morphogenesis, secondary metabolism, and pathogenicity of A. flavus mediated by the H4K20-methyltransferase Set9, which might provide a potential new target for early prevention of contamination of A. flavus and its deadly mycotoxins.

Does the Use of Different Types of Probiotics Possess Detoxification Properties Against Aflatoxins Contamination in Rabbit Diets?

The present work was carried out to study the ability of five probiotics on the in vitro degradation of Aflatoxins B1 (AFB1). The best results of in vitro were tested on the detoxification of AFB1 in rabbits. A total of 40 growing New Zealand White (NZW) male rabbits were assigned to five experimental groups. Animals were fed the following diets: basal diet (control), basal diet contaminated with 300 ppb AFB1, basal diet contaminated with 300 ppb AFB1. + probiotic 3 (0.5 g/kg diet), basal diet contaminated with 300 ppb AFB1 + ajowan (0.5 g/kg diet), and basal diet contaminated with 300 ppb AFB1 + probiotic 3 (0.5 g/kg diet) + ajowan (0.5 g/kg diet). Live body weight significantly (P < 0.05) decreased in rabbits fed AFB1 contaminated diet compared to the control rabbits. All additives improved (P < 0.05) the live body weight. The best improvement occurred with probiotics + ajowan. The addition of probiotics increased (P < 0.05) daily body weight gain in all weeks except the first week. Adding ajowan or ajowan + probiotic led to a significant (P < 0.05) increase in live body weight gain and feed intake compared to rabbits fed AFB1 alone. The digestion coefficients of dry matter (DM), organic matter (OM), crude fiber (CF), ether extract (EE), nitrogen-free extract (NFE), and digestible crude protein (DCP) significantly (P < 0.05) decreased in rabbits fed AFB1 contaminated diet. All additives improved (P < 0.05) the digestibility coefficients of DM, OM, EE, CF, NFE, and total digested nutrients (TDN)%. The best improvement occurred with probiotics + ajowan. Concentrations of serum total protein, albumin and globulin significantly (P < 0.05) decreased in rabbits fed AFB1 contaminated diet compared with the control rabbits. In conclusion, the addition of probiotic 3 (AVI-5-BAC) + ajowan could be recommended to eliminate the toxicity of AFB1 and improve growth performance criteria in rabbits.

Screening of the phytochemical constituents of Teucrium polium extract and evaluation of their prophylactic role against the oxidative damage and cytotoxicity of Aflatoxin B1 in rats

Aflatoxin B1 (AFB1) is common carcinogen causing acute and chronic hepatocyte injuries. This study aimed to determine the bioactive components of Teucrium polium methanolic extract (TPE) and to evaluate their protective role against AFB1-induced oxidative damage, cytotoxicity, and genotoxicity in rats. Six groups of male albino rats were treated orally for 4 weeks including the control group, the ِAFB1-treated group (80 μg/kg b.w.), the groups treated with low (LD) or high (HD) dose TPE (50 or 100 mg/kg b.w.), and the groups treated with AFB1 plus TEP (LD) or TPE (HD). Blood and serum samples were collected for different assays. The GC-MS identified 34 compounds, the major compounds were pinene, germacrene D, α-cadinol, α-thujene, epi-bicyclosesquiphellandrene, and limonene. Animals that received AFB1 showed significant changes in all indicators of oxidative stress, biochemistry, cytokines, MNPCEs, comet tail formation in bone marrow, mRNA expression of inflammatory-related genes, Nrf2, and iNOS beside histological changes in the liver. TPE at the two doses tested showed insignificant changes in all tested parameters. The extract could normalize most of these parameters and the hepatic structure in AFB1-treated animals in a dose-dependent fashion. therefore, we concluded that TPE supplementation is effective for protection against AFB1 in endemic areas.

Degradation of zearalenone by microorganisms and enzymes

Mycotoxins are toxic metabolites produced by fungi that may cause serious health problems in humans and animals. Zearalenone is a secondary metabolite produced by fungi of the genus Fusarium, widely exists in animal feed and human food. One concern with the use of microbial strains and their enzyme derivatives for zearalenone degradation is the potential variability in the effectiveness of the degradation process. The efficiency of degradation may depend on various factors such as the type and concentration of zearalenone, the properties of the microbial strains and enzymes, and the environmental conditions. Therefore, it is important to carefully evaluate the efficacy of these methods under different conditions and ensure their reproducibility. Another important consideration is the safety and potential side effects of using microbial strains and enzymes for zearalenone degradation. It is necessary to evaluate the potential risks associated with the use of genetically modified microorganisms or recombinant enzymes, including their potential impact on the environment and non-target organisms. Additionally, it is important to ensure that the degradation products are indeed harmless and do not pose any health risks to humans or animals. Furthermore, while the use of microbial strains and enzymes may offer an environmentally friendly and cost-effective solution for zearalenone degradation, it is important to explore other methods such as physical or chemical treatments as well. These methods may offer complementary approaches for zearalenone detoxification, and their combination with microbial or enzyme-based methods may improve overall efficacy. Overall, the research on the biodegradation of zearalenone using microorganisms and enzyme derivatives is promising, but there are important considerations that need to be addressed to ensure the safety and effectiveness of these methods. Development of recombinant enzymes improves enzymatic detoxification of zearalenone to a non-toxic product without damaging the nutritional content. This review summarizes biodegradation of zearalenone using microorganisms and enzyme derivatives to nontoxic products. Further research is needed to fully evaluate the potential of these methods for mitigating the impact of mycotoxins in food and feed.

Mycotoxins and consumers' awareness: Recent progress and future challenges

While food shortages have become an important challenge, providing safe food resources is a point of interest on a global scale. Mycotoxins are secondary metabolites that are formed through various fungi species. They are mainly spread through diets such as food or beverages. About one quarter of the world's food is spoiled with mycotoxins. As this problem is not resolved, it represents a significant threat to global food security. Besides the current concerns regarding the contamination of food items by these metabolites, the lack of knowledge by consumers and their possible growth and toxin production attracted considerable attention. While globalization provides a favorite condition for some countries, food security still is challenging for most countries. There are various approaches to reducing the mycotoxigenic fungi growth and formation of mycotoxins in food, include as physical, chemical, and biological processes. The current article will focus on collecting data regarding consumers' awareness of mycotoxins. Furthermore, a critical overview and comparison among different preventative approaches to reduce risk by consumers will be discussed. Finally, the current effect of mycotoxins on global trade, besides future challenges faced by mycotoxin contamination on food security, will be discussed briefly.

Tuning Thermostability and Catalytic Efficiency of Aflatoxin-Degrading Enzyme by Error-prone PCR

In our previous work, a recombinant aflatoxin-degrading enzyme derived from Myxococcus fulvus (MADE) was reported. However, the low thermal stability of the enzyme had limitations for its use in industrial applications. In this study, we obtained an improved variant of recombinant MADE (rMADE) with enhanced thermostability and catalytic activity using error-prone PCR. Firstly, we constructed a mutant library containing over 5000 individual mutants. Three mutants with T₅₀ values higher than the wild-type rMADE by 16.5 °C (rMADE-1124), 6.5 °C (rMADE-1795), and 9.8 °C (rMADE-2848) were screened by a high-throughput screening method. Additionally, the catalytic activity of rMADE-1795 and rMADE-2848 was improved by 81.5% and 67.7%, respectively, compared to the wild-type. Moreover, structural analysis revealed that replacement of acidic amino acids with basic amino acids by a mutation (D114H) in rMADE-2848 increased the polar interactions with surrounding residues and resulted in a threefold increase in the t_1/2 value of the enzyme and made it more thermaltolerate. KEY POINTS: • Mutant libraries construction of a new aflatoxins degrading enzyme by error-prone PCR. • D114H/N295D mutant improved enzyme activity and thermostability. • The first reported enhanced thermostability of aflatoxins degrading enzyme better for its application.

Isolation, Identification, and Characterization of the Native Yeast Strains from Homemade Cheese to Assess their Eliminating Impact on the Aflatoxin B1 and M1 of the Simulated Gastrointestinal Fluid

Background

The occurrence of aflatoxins in food products is a silent threat to human health worldwide. A range of strategies has been introduced to address the bioavailability of aflatoxins, which are considered microbial tools to provide a low-cost and promising approach.

Objectives

The present study focused on the separation of yeast strains from the homemade cheese rind layer to investigate the ability of native yeasts to eliminate AB1 and AM1 from simulated gastrointestinal fluids.

Material and Methods

Homemade cheese samples were prepared from different locations in Tehran provinces and yeast strains were isolated and identified through the biochemical methods and molecular analysis of internal transcribed spacer and D1/D2 domain of 26S rDNA regions. Isolated strains were screened using simulated gastrointestinal fluids, and the ability of yeast strains to absorb aflatoxin was evaluated.

Results

Out of 13 strains, 7 yeast strains were not affected by 5 ppm AFM1 while 11 strains did not show any significant response to 5 mg.L^-1 (ppm) of AFB1. On the other hand, 5 strains were able to successfully tolerate 20 ppm AFB1. Candidate yeasts showed different abilities to remove aflatoxins B1 and M1. In addition, C. lusitaniae, G. geotrichum, G. candidum, and C. sanyaensis exhibited a significant ability to detoxify aflatoxins from the gastrointestinal fluid, respectively.

Conclusion

Our data suggest that yeast communities with essential effects on the quality of homemade cheese appear to be precise candidates for the potential elimination of aflatoxins from the gastrointestinal fluid.

Assessment of aflatoxin exposure, growth faltering and the gut microbiome among children in rural Guatemala: protocol for an observational prospective cohort and bioreactor simulations

INTRODUCTION

Aflatoxin B1 (AFB1) is a carcinogen produced by Aspergillus flavus and Aspergillus parasiticus which grow on maize. Given the high prevalence of child stunting (ie, impaired growth) and other nutritional disorders in low-income and middle-income countries, where maize is consumed, the role of aflatoxin exposure may be significant. Observational reports have demonstrated associations between aflatoxin exposure and impaired child growth; however, most have been cross-sectional and have not assessed seasonal variations in aflatoxin, food preparation and dynamic changes in growth. Biological mechanistic data on how aflatoxin may exert an impact on child growth is missing. This study incorporates a prospective cohort of children from rural Guatemala to assess (1) temporal associations between aflatoxin exposure and child growth and (2) possible mediation of the gut microbiome among aflatoxin exposure, inflammation and child growth.

METHODS AND ANALYSIS

We will prospectively evaluate aflatoxin exposure and height-for-age difference trajectories for 18 months in a cohort of 185 children aged 6-9 months at enrolment. We will assess aflatoxin exposure levels and biomarkers of gut and systemic inflammation. We will examine the faecal microbiome of each child and identify key species and metabolic pathways for differing AFB1 exposure levels and child growth trajectories. In parallel, we will use bioreactors, inoculated with faeces, to investigate the response of the gut microbiome to varying levels of AFB1 exposure. We will monitor key microbial metabolites and AFB1 biotransformation products to study nutrient metabolism and the impact of the gut microbiome on aflatoxin detoxification/metabolism. Finally, we will use path analysis to summarise the effect of aflatoxin exposure and the gut microbiome on child growth.

ETHICS AND DISSEMINATION

Ethics approval was obtained from Arizona State University Institutional Review Board (IRB; STUDY00016799) and Wuqu' Kawoq/Maya Health Alliance IRB (WK-2022-003). Findings will be disseminated in scientific presentations and peer-reviewed publications.

A consortium of detoxifying bacteria mitigates the aflatoxin B1 toxicosis on performance, health, and blood constituents of laying hens

Detoxification approaches are evolving from physical to biological to eliminate the toxins altogether. The current study was conducted to compare the impact of 2 newly developed toxin deactivators, Magnotox-alphaA (MTA) and Magnotox-alphaB (MTB) with a commercially available toxin binder, Mycofix Plus^{MTV INSIDE} (MF) in alleviating the pernicious effects of aflatoxin B1 (AFB1) in laying hens. The treatments were: 1) negative control (NC; without AFB1), 2) positive control (PC; contaminated with 500 ppb AFB1), 3) MF (PC + 2 kg MF/ton feed), 4) MTA (PC + 2 kg MTA/ton feed), and 5) MTB (PC + 2 kg MTB/ton feed). Detoxifying bacteria revealed a substantial reduction of different toxins in vitro, in which 98.8, 94.5, and 73.3% degradation rates were achieved, respectively, for zearalenone (ZEN), patulin, and AFB1 in the first 1 h of exposure. The PC group had a sharp decline in egg production (EP; 68.83%) while MTB showed the superior EP (95.74%) followed by NC (90.66%), MF (86.57%), and MTA (82.08%; P ≤ 0.05). Egg weight (EW) was also observed to be inferior in PC group (53.80 g; P ≤ 0.05). Egg mass (EM) was higher in MTB (57.55 g) and NC (54.33 g) groups while PC produced the lowest (39.64 g; P ≤ 0.05). MTB and NC groups also demonstrated the best FCR, 1.62 and 1.68, respectively, and PC manifested the poorest FCR (1.98) with higher ADFI (P ≤ 0.05). MTB also produced a superior moisture content (MC; 82.11%) with inferior DM (17.89%) in ileum content (P ≤ 0.05). The greatest liver fat content was found in MF group (48.19%) and MTA yielded the superior serum β-carotene and Vit A. MDA level in yolk samples was influenced by treatments, rendering the highest level in PC group (P ≤ 0.05). Ileum microbiota and blood characteristics were also affected by treatments. In general, MTB proves to be a toxin-deactivator candidate with comparable results to that of commercially available toxin-binders.

Electrospun Membranes Anchored with g-C3N4/MoS2 for Highly Efficient Photocatalytic Degradation of Aflatoxin B1 under Visible Light

The degradation of aflatoxin (AF) is a topic that always exists along with the food and feed industry. Photocatalytic degradation as an advanced oxidation technology has many benefits, including complete inorganic degradation, no secondary contamination, ease of activity under moderate conditions, and low cost compared with traditional physical, chemical, and biological strategies. However, photocatalysts are usually dispersed during photocatalytic reactions, resulting in energy and time consumption in the separation process. There is even a potential secondary pollution problem from the perspective of food safety. In this regard, three electrospun membranes anchored with g-C₃N₄/MoS₂ composites were prepared for highly efficient photocatalytic degradation of aflatoxin B₁ (AFB₁) under visible light. These photocatalytic membranes were characterized by XRD, SEM, TEM, FTIR, and XPS. The factors influencing the degradation efficiency of AFB₁, including pH values and initial concentrations, were also probed. The three kinds of photocatalytic membranes all exhibited excellent ability to degrade AFB₁. Among them, the photocatalytic degradation efficiency of the photocatalytic membranes prepared by the coaxial methods reached 96.8%. The experiment is with an initial concentration of 0.5 μg/mL (500 PPb) after 60 min under visible light irradiation. The mechanism of degradation of AFB₁ was also proposed based on active species trapping experiments. Moreover, the prepared photocatalytic membranes exhibited excellent photocatalytic activity even after five-fold use in the degradation of AFB₁. These studies showed that electrospun membranes anchored with g-C₃N₄/MoS₂ composites have a high photocatalytic ability which is easily removed from the reacted medium for reuse. Thereby, our study offers a highly effective, economical, and green solution for AFB₁ degradation in the foodstuff for practical application.

Taraxasterol alleviates aflatoxin B1-induced liver damage in broiler chickens via regulation of oxidative stress, apoptosis and autophagy

Aflatoxin B₁ (AFB₁) is the most dangerous and abundant mycotoxin, which is toxic to almost all animals, and poultry is more sensitive to AFB₁ toxicity. Ingesting AFB₁-contaminated feed can cause significant liver damage and brings serious harm to poultry, which greatly restricts the development of the poultry industry. The present research was implemented to explore the intervention effect and its mechanism of taraxasterol on liver damage induced by AFB₁ in broiler chickens. The liver damage model in broiler chickens was established by feeding 0.5 mg/kg AFB₁ feed, and taraxasterol (25, 50 and 100 mg/kg BW, respectively) was given in the drinking water for 21 days. The growth performance, liver function, oxidative stress, apoptosis and autophagy were evaluated. The results showed that taraxasterol increased BW and reduced feed-to-gain ratio of broiler chickens induced by AFB₁. Taraxasterol improved the levels of serum alanine aminotransferase (ALT), aspartate aminotransferase (AST), γ-glutamyltransferase (GGT), total bilirubin (TBIL) and alkaline phosphatase (ALP), and attenuated hepatic histopathological changes induced by AFB₁. Meantime, taraxasterol down-regulated cytochrome P450 (CYP450) enzyme system CYP1A1 and CYP2A6 mRNA expression, inhibited the overproduction of reactive oxygen species (ROS) and malondialdehyde (MDA), and enhanced the activities of antioxidant enzymes glutathione (GSH) and catalase (CAT) and the content of antioxidant superoxide dismutase (SOD) of the liver in broiler chickens induced by AFB₁. Furthermore, taraxasterol up-regulated the mRNA and protein expression of hepatic nuclear factor E2 related factor 2 (Nrf2), heme oxygenase 1 (HO-1) and NAD(P)H: quinone oxidoreductase 1 (NQO1), and down-regulated the expression of hepatic kelch like ECH associated protein 1 (Keap1) induced by AFB₁ in Keap1/Nrf2 signaling pathway. The ultrastructural observation and RT-qPCR results found that taraxasterol inhibited apoptosis of hepatocytes, up-regulated the expression of B-cell lymphoma-2 (Bcl-2) mRNA and down-regulated the expression of Bax and caspase3 mRNA. Further, taraxasterol restored the autophagy of hepatocytes and down-regulated the mRNA expression of phosphatidylinositol 3-kinase K (PI3K), protein kinase B (AKT) and mammalian target of rapamycin (mTOR) in AFB₁-induced liver of broiler chickens. The above results indicate that taraxasterol alleviates liver damage induced by AFB₁ in broiler chickens through regulation of Keap1/Nrf2 signaling pathway to exert its antioxidant effect, mitochondrial apoptosis pathway to improve anti-apoptotic ability and PI3K/AKT/mTOR pathway to restore autophagy.

Cloning and expression of the catalase gene (KatA) from Pseudomonas aeruginosa and the degradation of AFB1 by recombinant catalase

BACKGROUND

Aflatoxin B₁ (AFB₁ ) poses a severe threat to human and animal health. Countries worldwide have invested considerable manpower and material resources in degrading aflatoxins. Enzyme degradation is the most efficient and environmentally friendly approach for modifying aflatoxin into less toxic molecules. Catalase is commonly used as a detoxification agent to decrease the contamination levels of aflatoxins in animal feeds. This study aimed to obtain recombinant catalase via gene engineering and determined whether a recombinant catalase could degrade AFB₁ .

RESULTS

The catalase gene (KatA) from Pseudomonas aeruginosa was cloned and expressed in Escherichia coli, and the expression conditions of this recombinant catalase were optimized. The recombinant catalase was isolated and purified using Ni-chelating affinity chromatography, and its ability to degrade AFB₁ was evaluated. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis showed that the expressed of catalase was approximately 55.6 kDa, which was subsequently purified using Ni-chelating affinity chromatography. The degradation rate of AFB₁ by recombinant catalase in the presence of syringaldehyde was 38.79%.

CONCLUSION

The degradation of AFB₁ by a recombinant catalase has been reported for the first time. This study provides a new paradigm for the use of recombinant catalases in degrading AFB₁ in food and feed. © 2022 Society of Chemical Industry.

Microbial Enzymes Involved in the Biotransformation of Major Mycotoxins

Mycotoxins, the most researched biological toxins, can contaminate food and feed, resulting in severe health implications for humans and animals. Physical, chemical, and biological techniques are used to mitigate mycotoxin contamination. The biotransformation method using whole microbial cells or isolated enzymes is the best choice to mitigate mycotoxins. Using specific enzymes may avoid the disadvantages of utilizing a full microbe, such as accidental harm to the product's organoleptic characteristics and hazardous safety features. Moreover, the degradation rates of the isolated enzymes are higher than those of the whole-cell reactions, and they are substrate-specific. Their specificity is comprehensive and is shown at the positional and/or chiral center in many circumstances. Currently, only a few enzymes of microbial origin are commercially available. Therefore, there is a need to identify more novel enzymes of microbial origin that can mitigate mycotoxins. In this review, we conducted an in-depth summary of the microbial enzymes involved in the biotransformation of mycotoxins.

Mitigation of aflatoxin B1 in fish feed by peroxidase from soybean meal

Potential of the enzyme peroxidase (PO) from soybean meal to mitigate aflatoxin B₁ (AFB₁) in fish feed was evaluated. Reaction parameters studied in the wet stage of the feed production process were enzyme activity (0.01-0.1 U/g), temperature (20-36 °C), time (0-8 h) and humidity content (40-70%). Feed was produced in conformity with the National Research Council and spiked with AFB₁ at 10 ng/g. Any residual concentration of AFB₁ in the diet was extracted by the QuEChERS method and quantified by a liquid chromatograph with a fluorescence detector. AFB₁ mitigation of 90% was reached when feed production conditions were 0.035 U/g, 32 °C, 6 h and 70% humidity. Therefore, application of PO to the feed industry may be considered a promising tool for mitigation of AFB₁, considering its toxicity and frequent occurrence. In addition, it guarantees safe food for consumers of fish farming products, as AFB₁ can bioaccumulate in the food chain. It also provides an alternative use for soybean meal that would previously be discarded.

Differential Expression of Genes Related to Growth and Aflatoxin Synthesis in Aspergillus flavus When Inhibited by Bacillus velezensis Strain B2

Aspergillus flavus is a saprophytic soil fungus that infects and contaminates seed crops with the highly carcinogenic aflatoxin, which brings health hazards to animals and humans. In this study, bacterial strains B1 and B2 isolated from the rhizosphere soil of camellia sinensis had significant antagonistic activities against A. flavus. Based on the phylogenetic analysis of 16SrDNA gene sequence, bacterial strains B1 and B2 were identified as Bacillus tequilensis and Bacillus velezensis, respectively. In addition, the transcriptome analysis showed that some genes related to A. flavus growth and aflatoxin synthesis were differential expressed and 16 genes in the aflatoxin synthesis gene cluster showed down-regulation trends when inhibited by Bacillus velezensis strain B2. We guessed that the Bacillus velezensis strain B2 may secrete some secondary metabolites, which regulate the related gene transcription of A. flavus to inhibit growth and aflatoxin production. In summary, this work provided the foundation for the more effective biocontrol of A. flavus infection and aflatoxin contamination by the determination of differential expression of genes related to growth and aflatoxin synthesis in A. flavus when inhibited by B. velezensis strain B2.

Isolation and Aflatoxin B1-Degradation Characteristics of a Microbacterium proteolyticum B204 Strain from Bovine Faeces

Aflatoxin B₁ (AFB₁) is one of the most harmful mycotoxins, raising serious global health and economic problems. Searching for biological approaches for effective and safe AFB₁ degradation is imminent. In our study, Microbacterium proteolyticum B204 isolated from bovine faeces degraded 77% of AFB₁ after 24 h, becoming the first reported bacteria from the Microbacterium family to possess AFB₁ degradation characteristics. Temperature variation showed little effect on its degradation ratio, demonstrating high thermostability of 75% and 79% after boiling and sterilization, respectively. We suppose that the components playing a key role during this process were proteins, considering the decreased degradation rate caused by Proteinase K. Cell viability detection on HepG2 cells indicated that the degradation products were much less toxic than pure AFB₁. Furthermore, B204 cell-free culture supernatant also degraded AFB₁-contaminated food, such as peanuts, corn and cheese. These results suggested that this strain with AFB₁ degradation properties could be a prospective candidate for application in the food and feed industries.

Synergistic Effects of Probiotic Bifidobacterium Isolated from Chicken's Intestine in Combination with Polyvinylpyrrolidone on Reduction of Aflatoxin B1

Food contamination with aflatoxin is one of the most critical concerns of health professionals. One of the best ways to reduce aflatoxin content in food is probiotics. Therefore, this study was performed to isolate Bifidobacterium from the chick's intestine; evaluate its probiotic activities and its application with Polyvinylpyrrolidone (PVP) to reduce aflatoxin B₁ (AFB₁ ) in the medium were investigated. Samples were isolated from the chick's intestine, and Bifidobacterium was isolated and identified by biochemical and molecular methods. Next, the potential probiotic characterization was assessed. Afterward, the effect of selected isolate and PVP on reducing AFB₁ in the medium was studied using ELISA and HPLC. Biochemical and molecular evaluations indicated isolation of Bifidobacterium bifidum strain from chick's intestine. One of the B. bifidum strains was selected for the next steps, which showed potential probiotic characterization and the ability to reduce the concentration of AFB₁ in the medium (50% reduction). When used in combination with PVP showed synergistic effects in reducing the concentration of AFB₁ from the medium (up to 90%). In conclusion, it was found that selected B. bifidum strains and PVP could have synergistic effects in reducing AFB₁ toxin in a medium up to 90%.

Trichoderma Enzymes for Degradation of Aflatoxin B1 and Ochratoxin A

The contamination of agricultural products with mycotoxins causes risks to animal and human health and severe economic losses. Mycotoxicoses can be reduced by preventing fungal infection using chemical and biological approaches. The chemical strategies can release toxic molecules; therefore, strategies for biological control are being evaluated, such as using nontoxic fungi and their metabolites. This work evaluated the effect of exoenzymes produced by the beneficial fungus Trichoderma afroharzianum strain T22 in degrading Aflatoxin B1 (AFB1) and Ochratoxin A (OTA). The ability of Trichoderma to produce hydrolases was stimulated by using different inducing substrates. The highest AFB1 and OTA degradation activity was obtained using a medium containing lyophilized mushrooms and crude fiber. The T. afroharzianum T22’s ability to reduce mycotoxins may be attributed to peroxidase enzymes. This study showed that T.afroharzianum strain T22 or its peroxidase supplementation could represent a sustainable strategy for the degradation of AFB1 and OTA in feed and food products.

Detoxification approaches of mycotoxins: by microorganisms, biofilms and enzymes

Mycotoxins are generally found in food, feed, dairy products, and beverages, subsequently presenting serious human and animal health problems. Not surprisingly, mycotoxin contamination has been a worldwide concern for many research studies. In this regard, many biological, chemical, and physical approaches were investigated to reduce and/or remove contamination from food and feed products. Biological detoxification processes seem to be the most promising approaches for mycotoxins removal from food. The current review details the newest progress in biological detoxification (adsorption and metabolization) through microorganisms, their biofilms, and enzymatic degradation, finally describing the detoxification mechanism of many mycotoxins by some microorganisms. This review also reports the possible usage of microorganisms as mycotoxins’ binders in various food commodities, which may help produce mycotoxins-free food and feed.

Isolation, Purification, and Characterization of a Laccase-Degrading Aflatoxin B1 from Bacillus amyloliquefaciens B10

Aflatoxins, widely found in feed and foodstuffs, are potentially harmful to human and animal health because of their high toxicity. In this study, a strain of Bacillus amyloliquefaciens B10 with a strong ability to degrade aflatoxin B1 (AFB1) was screened; it could degrade 2.5 μg/mL of AFB1 within 96 h. The active substances of Bacillus amyloliquefaciens B10 for the degradation of AFB1 mainly existed in the culture supernatant. A new laccase with AFB1-degrading activity was separated by ammonium sulfate precipitation, diethylaminoethyl (DEAE) and gel filtration chromatography. The results of molecular docking showed that B10 laccase and aflatoxin had a high docking score. The coding sequence of the laccase was successfully amplified from cDNA by PCR and cloned into E. coli. The purified laccase could degrade 79.3% of AFB1 within 36 h. The optimum temperature for AFB1 degradation was 40 °C, and the optimum pH was 6.0–8.0. Notably, Mg²⁺ and dimethyl sulfoxide (DMSO) could enhance the AFB1-degrading activity of B10 laccase. Mutation of the three key metal combined sites of B10 laccase resulted in the loss of AFB1-degrading activity, indicating that these three metal combined sites of B10 laccase play an essential role in the catalytic degradation of AFB1.

[In vivo and In vitro Mitigation Effects of Lactic Acid Bacteria Derived from Fresh Vegetables on Aflatoxins]

Aflatoxins (AFs) are known to be oncogenic mycotoxins. This study investigated the mitigation effects of lactic acid bacteria (LAB) isolated from four types of vegetable, cucumber, Chinese cabbage, Japanese radish and eggplant, which are used to make Japanese traditional fermented pickles, on AFs. Using aflatoxin M₁ (AFM₁) binding assay for screening, four representative strains were selected (one from each vegetable) from total 94 LAB strains, based on the highest binding ratio. The ranges of the binding ratio of these representative strains to aflatoxin B₁ (AFB₁), aflatoxin B₂, aflatoxin G₁, aflatoxin G₂ and AFM₁ were 57.5%-87.9% for the LAB strain derived from cucumber, 18.9%-43.9% for the LAB strain derived from Chinese cabbage, 26.4%-41.7% for the LAB strain derived from Japanese radish, and 15.0%-42.6% for the LAB strain derived from eggplant. The strains isolated from cucumber, Chinese cabbage, Japanese radish and eggplant were identified as Lactococcus lactis subsp. lactis, Weissella cibaria, Leuconostoc mesenteroides and Leu. mesenteroides, respectively. An in vitro binding assay of the four strains under acidic conditions showed that the number of living bacteria decreased, while the binding ratio increased in some strains, suggesting that the LAB maintained their capacity to bind aflatoxins even in an environment that imitated the stomach. An in vivo experiment using L. lactis subsp. lactis derived from cucumber revealed that the bacteria significantly inhibited the absorption of AFB₁ into blood. These results showed that the LAB used for Japanese vegetable pickles was an effective binding agent of AFs and suggested that they might play a role in mitigating AF absorption.

Aflatoxins: History, Significant Milestones, Recent Data on Their Toxicity and Ways to Mitigation

In the early 1960s the discovery of aflatoxins began when a total of 100,000 turkey poults died by hitherto unknown turkey "X" disease in England. The disease was associated with Brazilian groundnut meal affected by Aspergillus flavus. The toxin was named Aspergillus flavus toxin-aflatoxin. From the point of view of agriculture, aflatoxins show the utmost importance. Until now, a total of 20 aflatoxins have been described, with B1, B2, G1, and G2 aflatoxins being the most significant. Contamination by aflatoxins is a global health problem. Aflatoxins pose acutely toxic, teratogenic, immunosuppressive, carcinogenic, and teratogenic effects. Besides food insecurity and human health, aflatoxins affect humanity at different levels, such as social, economical, and political. Great emphasis is placed on aflatoxin mitigation using biocontrol methods. Thus, this review is focused on aflatoxins in terms of historical development, the principal milestones of aflatoxin research, and recent data on their toxicity and different ways of mitigation.

Bacillus amyloliquefaciens B10 can alleviate liver apoptosis and oxidative stress induced by aflatoxin B1

Aflatoxin B1 (AFB1) is a mycotoxin often found in food and livestock feed. It can affect human and animal health and is especially damaging to the liver. This study aims to evaluate whether Bacillus amyloliquefaciens (hereafter referred to as B. amyloliquefaciens) B10 can alleviate the toxic effects of AFB1 and, if so, what mechanism is responsible for its action. Specific pathogen-free (SPF) Kunming mice (5-6 weeks old) were divided into four groups (Control, AFB1, B10 strain, and AFB1 + B10 strain) and conducted continuously via gavage for 28 days. Oxidation indices (MDA, T-AOC, SOD, GSH-Px, and CAT) were then measured using their liver tissues and liver coefficient were calculated. Apoptosis was determined using the TUNEL method. Gene expression was determined for Bax, Bcl-2, BIP, CHOP, JNK, Caspase-12, Caspase-9, and Caspase-3, and protein expression was detected for Bax, Bcl-2, and Caspase-3. Our results showed that AFB1 induced the oxidative damage and apoptosis in the livers of mice. However, for mice given B. amyloliquefaciens B10, the biochemical indices, pathological changes, the expressions of genes and proteins related to oxidative stress and apoptosis were significantly reversed. The results indicate that B. amyloliquefaciens B10 antagonizes oxidative damage and apoptosis induced by AFB1 in the livers of mice. The results of this study are of significance for the future use of this strain to reduce the harm of AFB1 to human health and animal reproductive performance.