Aflatoxin B1 binding by a mixture of Lactobacillus and Propionibacterium: in vitro versus ex vivo

Biodegradation of Aflatoxin B1 in the Baijiu Brewing Process by Bacillus cereus

Aflatoxin is a potent mycotoxin and a common source of grain contamination that leads to great economic losses and health problems. Although distilled baijiu cannot be contaminated by aflatoxin, its presence in the brewing process affects the physiological activities of micro-organisms and reduces product quality. Bacillus cereus XSWW9 capable of degrading aflatoxin B1 (AFB1) was isolated from daqu using coumarin as the sole carbon source. XSWW9 degraded 86.7% of 1 mg/L AFB1 after incubation at 37 °C for 72 h and tolerated up to 1 mg/L AFB1 with no inhibitory effects. Enzymes in the cell-free supernatant of XSSW9 played a significant role in AFB1 degradation. The AFB1-degradation activity was sensitive to protease K and SDS treatment, which indicated that extracellular proteins were responsible for the degradation of AFB1. In order to investigate the AFB1-degradation ability of XSSW9 during the baijiu brewing process, AFB1 and XSWW9 were added to grain fermentation (FG-T) and normal grain fermentation without AFB1, while normal grain fermentation without AFB1 and XSWW9 was used as a control (FG-C). At the end of the fermentation, 99% AFB1 was degraded in the residue of fermented grains. The differences of microbial communities in the fermented grains showed that there were no significant differences between FG-T and FG-C in the relative abundance of dominant genera. The analysis of volatile compounds of their distillation showed that the contents of skeleton flavor components was similar between FG-T and FG-C. These results offer a basis for the development of effective strategies to reduce the effect of AFB1 on the brewing process and ensure that the production of baijiu is stable.

Avian Cell Culture Models to Study Immunomodulatory Properties of Bioactive Products

Antimicrobial resistance is becoming a greater danger to both human and animal health, reducing the capacity to treat bacterial infections and increasing the risk of morbidity and mortality from resistant bacteria. Antimicrobial efficacy in the treatment of bacterial infections is still a major concern in both veterinary and human medicine. Antimicrobials can be replaced with bioactive products. Only a small number of plant species have been studied in respect to their bioactive compounds. More research is needed to characterize and evaluate the therapeutic properties of the plant extracts. Due to the more and more common phenomenon of antimicrobial resistance, poultry farming requires the use of natural alternatives to veterinary antibiotics that have an immunomodulatory effect. These include a variety of bioactive products, such as plant extracts, essential oils, probiotics, prebiotics, and synbiotics. This article presents several studies on bioactive products and their immunomodulatory effects tested in vitro and ex vivo using various avian cell culture models. Primary cell cultures that have been established to study the immune response in chickens include peripheral blood mononuclear cells (PBMCs), intestinal epithelial cells (IEC), and bone marrow-derived dendritic cells (BMDCs). Chicken lymphatic lines that can be used to study immune responses are mainly: chicken B cells infected with avian leukemia RAV-1 virus (DT40), macrophage-like cell line (HD11), and a spleen-derived macrophage cell line (MQ-NCSU). Ex vivo organ cultures combine in vitro and in vivo studies, as this model is based on fragments of organs or tissues grown in vitro. As such, it mimics the natural reactions of organisms, but under controlled conditions. Most ex vivo organ cultures of chickens are derived from the ileum and are used to model the interaction between the gastrointestinal tract and the microbiota. In conclusion, the use of in vitro and ex vivo models allows for numerous experimental replications in a short period, with little or no ethical constraints and limited confounding factors.

Evaluation of acrylamide-removing properties of bacterial consortia under simulated gastrointestinal conditions

BACKGROUND

Previous studies have demonstrated the acrylamide-removing properties of probiotic monocultures; however, potential advantages of consortia over monocultures in reducing the dietary exposure to acrylamide have not been proven. Hence this work aims to assess the acrylamide (AA)-binding properties of bacterial consortia, consisting of either probiotic strains and / or representative bacteria of duodenal microbiota, exposed to simulated gastrointestinal conditions (SGC). The AA binding capacity of ten probiotic strains (PS) and six duodenal strains (NDS) was evaluated under different conditions; then, three different consortia (PS, NDS, and PS + NDS) were assessed under SGC.

RESULTS

Among individual PS, Bacillus coagulans GBI-30, Lactobacillus fermentum J23, L. pentosus J37 and J24, and L. casei Shirota, exhibited the highest AA-binding capacity (80-87%), while Bifidobacterium catenulatun ATCC27676, Streptococcus salivarius subsp. thermophilus ATCC19258, and S. gallolyticus ATCC9809 were the best (ca. 68%) NDS monocultures. Probiotic strain consortia showed higher (P < 0.05) AA binding capacity (> 90%) than monoculture bacteria. Conversely, individual NDS cultures displayed higher (P < 0.05) binding capacity than NDS consortia (60%). A significant reduction (P < 0.05) in AA removal capacity was observed when consortia were exposed to SGC, PS consortia being the most effective (> 60% removal).

CONCLUSION

These results suggest that consortia of specific PS could play an important role in reducing the intestinal availability of acrylamide. © 2021 Society of Chemical Industry.

In Vitro Detoxification of Aflatoxin B1, Deoxynivalenol, Fumonisins, T-2 Toxin and Zearalenone by Probiotic Bacteria from Genus Lactobacillus and Saccharomyces cerevisiae Yeast

The aim of the following research was to determine the detoxification properties of probiotic Lactobacillus sp. bacteria (12 strains) and S. cerevisiae yeast (6 strains) towards mycotoxins, such as aflatoxin B₁, deoxynivalenol, fumonisins, T-2 toxin and zearalenone, which pose as frequent feed contamination. The experiment involved analysing changes in concentration of mycotoxins in PBS solutions, after 6, 12 and 24 h of incubation with monocultures of tested microorganisms, measured by high-performance liquid chromatography (HPLC). We found that all strains detoxified the mycotoxins, with the highest reduction in concentration observed for the fumonisin B₁ and B₂ mixture, ranging between 62 and 77% for bacterial strains and 67–74% for yeast. By contrast, deoxynivalenol was the most resistant mycotoxin: its concentration was reduced by 19–39% by Lactobacillus sp. strains and 22–43% by yeast after 24 h of incubation. High detoxification rates for aflatoxin B₁, T-2 toxin and zearalenone were also observed, with concentration reduced on average by 60%, 61% and 57% by Lactobacillus, respectively, and 65%, 69% and 52% by yeast, respectively. The greatest extent of reduction in the concentration for all mycotoxins was observed after 6 h of incubation; however, a decrease in concentration was noted even after 24 h of incubation. Thus, the tested microorganisms can potentially be used as additives to decrease the concentrations of toxins in animal feed.

Anti-Toxigenic Effect of Lactic Acid Bacteria Against Aspergillus spp Isolated from Wheat Grains

Introduction:

Many fungi infect the wheat grains. Under field and or storage conditions from temperature and humidity, some fungi can produce aflatoxins (AFs), which may cause acute or chronic diseases. Therefore, there is a necessary and urgent need to find an effective and safe way to reduce or remove AFs.

Objective:

The objective of this study was the evaluation of Lactobacillus rhamnosus, Lactobacillus gasseri, and Lactobacillus plantarum for their ability to reduce and or remove AFs produced by Aspergillus flavus and Aspergillus parasiticus, which were isolated from wheat grains, as well as control of AFs produced on affected wheat grain by A.parasiticus spores only.

Methods:

LAB, isolated from some local dairy products, were cultured in MRS for the evaluation of their ability to remove AFs, produced by A. flavus and A. parasiticus on (YES) media, in addition to the treatment of wheat grains by LAB cells to prevent AFs produced by A. parasiticus.

Results:

The L. rhamnosus strain gave the highest reduction rates of AFs produced by A. parasiticus that were 62.6, 44.4, 43.3, and 52.2% for AFG1, AFB1, AFG2, and AFB2, respectively. While in the case of A. flavus, the reduction was 50.4, 42.7, 40.6, and 36.8% in the same order of toxins. When applied, these strains with wheat grains were affected by A. parasiticus, the inhibition rates of AFs were ranged between 61.4 and 75.8% with L. rhamnosus strain and 43.7 to 52.1% with L. gasseri, while L. plantarum strain ranged from 55.5 to 66.9%.

Conclusion:

According to this study, L. rhamnosus is considered one of the best strains in this field. Therefore, the present study suggests applied use of LAB as a treatment to prevent AFs production in wheat grains.

Decontamination of Aflatoxins by Lactic Acid Bacteria

Aflatoxins are toxic secondary metabolic products, which exert great hazards to human and animal health. Decontaminating aflatoxins from food ingredients to a threshold level is a prime concern for avoiding risks to the consumers. Biological decontamination processes of aflatoxins have received widespread attention due to their mild and environmental-friendly nature. Many reports have been published on the decontamination of aflatoxins by microorganisms, especially lactic acid bacteria (LAB), a well-explored probiotic and generally recognized as safe. The present review aims at updating the decontamination of produced aflatoxins using LAB, with an emphasis on the decontamination mechanism and influence factors for decontamination. This comprehensive analysis provides insights into the binding mechanisms between LAB and aflatoxins, facilitating the theoretical and practical application of LAB for decontaminating hazardous substances in food and agriculture.

Protective role of lactic acid bacteria and yeasts as dietary carcinogen-binding agents - a review

The importance of food contaminants in the link between diet and cancer has been widely demonstrated. Therefore, different physical and chemical strategies for the control of human exposure to such dietary carcinogens has been explored; however, most of these strategies are complex, costly, and have low efficiency which limited their applications. Hence, microbiological methods have been receiving more attention. Recent in vitro and in vivo studies have indicated that lactic acid bacteria (LAB) and yeast may act as dietary carcinogen-binding agents. This review describes the promising protective role of strains belonging mainly to the Lactobacillus, Bifidobacterium and Saccharomyces genera by acting as dietary carcinogen-binding agents. This property suggests that these microorganisms may have a protective role by reducing the bioaccessibility of dietary carcinogens, thereby decreasing their toxic effects. The mechanisms by which the binding process takes place have not been completely elucidated; thus, the possible underlying mechanisms and factors influencing carcinogens-binding will be addressed.

Current research and prevention of aflatoxins in China

Since their discovery in the 1960s, aflatoxins were found to have a considerable impact on the health of humans and animals as well as the country’s economy and international trade. Aflatoxins are often found in nuts, cereals and animal feeds, which has a significant danger to the food industry. Over the years, several steps have been undertaken worldwide to minimise their contamination in crops and their exposure to humans and animals. China is one of the largest exporters and importers of food and animal feed. As a result, many studies have been carried out in China related to aflatoxins, including their distribution, pollution, detection methods, monitoring, testing and managing. Chinese scientists studied aflatoxins in microbiological, toxicological, ecological effects as well as policies relating to their controlling. China has thus put into practice a number of strategies aiming at the prevention and control of aflatoxins in order to protect consumers and ensure a safe trade of food and feed, and the status and enlargement of these strategies are very important and useful for many consumers and stakeholders in China. Therefore, this article aims at the detriment assessments, regulations, distribution, detection methods, prevention and control of aflatoxins in China. It equally provides useful information about the recent safety management systems in place to fight the contamination of aflatoxins in food and feed in China.

Lactic Acid Bacteria as Antifungal and Anti-Mycotoxigenic Agents: A Comprehensive Review

Fungal contamination of food and animal feed, especially by mycotoxigenic fungi, is not only a global food quality concern for food manufacturers, but it also poses serious health concerns because of the production of a variety of mycotoxins, some of which present considerable food safety challenges. In today's mega-scale food and feed productions, which involve a number of processing steps and the use of a variety of ingredients, fungal contamination is regarded as unavoidable, even good manufacturing practices are followed. Chemical preservatives, to some extent, are successful in retarding microbial growth and achieving considerably longer shelf-life. However, the increasing demand for clean label products requires manufacturers to find natural alternatives to replace chemically derived ingredients to guarantee the clean label. Lactic acid bacteria (LAB), with the status generally recognized as safe (GRAS), are apprehended as an apt choice to be used as natural preservatives in food and animal feed to control fungal growth and subsequent mycotoxin production. LAB species produce a vast spectrum of antifungal metabolites to inhibit fungal growth; and also have the capacity to adsorb, degrade, or detoxify fungal mycotoxins including ochratoxins, aflatoxins, and Fusarium toxins. The potential of many LAB species to circumvent spoilage associated with fungi has been exploited in a variety of human food and animal feed stuff. This review provides the most recent updates on the ability of LAB to serve as antifungal and anti-mycotoxigenic agents. In addition, some recent trends of the use of LAB as biopreservative agents against fungal growth and mycotoxin production are highlighted.

Oral administration of Lactobacillus casei Shirota can ameliorate the adverse effect of an acute aflatoxin exposure in Sprague Dawley rats

Aflatoxin B₁(AFB₁) is a toxic compound commonly found in some crops with an adverse health effect on human and animals. Some beneficial microorganisms (or probiotics) such as lactic acid bacteria have shown the ability to reduce the bioavailability of aflatoxins and its intestinal absorption. However, the dose and duration of aflatoxins exposure and probiotic treatment can influence the ability of probiotics to remove aflatoxins. Therefore, this research aimed to investigate the efficacy of oral probiotic Lactobacillus casei Shirota strain (LcS) induction in an acute exposure to AFB₁ in rats. Experimentally, Sprague Dawley rats were divided into three groups: AFB₁ only (n = 9); AFB₁ treated with LcS (n = 9); and control (no AFB₁ exposure) (n = 6) groups. The blood AFB₁ level of rats treated with LcS was slightly lower than the untreated AFB₁ induced rats (11.12 ± 0.71 vs 10.93 ± 0.69 ng g^-1). Also, LcS treatment slightly moderated the liver and kidney biomarkers in AFB₁ induced rats. However, a trend for a significant difference was only observed in ALT of AFB₁ induced rats treated with LcS compared to their counterparts (126.11 ± 36.90 vs 157.36 ± 15.46, p = 0.06). Rats' body weight decreased in all animals force-fed with AFB₁ with no significant difference between LcS treatment compared to the counterpart. In conclusion, this experiment indicated that probiotic LsC was able to slightly ameliorate the adverse effect of an acute exposure to AFB₁ in rats. However, future studies with longer probiotics treatment or higher probiotics dose is required to confirm these findings.

Differential Transcriptome Responses to Aflatoxin B₁ in the Cecal Tonsil of Susceptible and Resistant Turkeys

The nearly-ubiquitous food and feed-borne mycotoxin aflatoxin B₁ (AFB₁) is carcinogenic and mutagenic, posing a food safety threat to humans and animals. One of the most susceptible animal species known and thus a good model for characterizing toxicological pathways, is the domesticated turkey (DT), a condition likely due, at least in part, to deficient hepatic AFB₁-detoxifying alpha-class glutathione S-transferases (GSTAs). Conversely, wild turkeys (Eastern wild, EW) are relatively resistant to the hepatotoxic, hepatocarcinogenic and immunosuppressive effects of AFB₁ owing to functional gene expression and presence of functional hepatic GSTAs. This study was designed to compare the responses in gene expression in the gastrointestinal tract between DT (susceptible phenotype) and EW (resistant phenotype) following dietary AFB₁ challenge (320 ppb for 14 days); specifically in cecal tonsil which functions in both nutrient absorption and gut immunity. RNAseq and gene expression analysis revealed significant differential gene expression in AFB₁-treated animals compared to control-fed domestic and wild birds and in within-treatment comparisons between bird types. Significantly upregulated expression of the primary hepatic AFB₁-activating P450 (CYP1A5) as well as transcriptional changes in tight junction proteins were observed in AFB₁-treated birds. Numerous pro-inflammatory cytokines, TGF-β and EGF were significantly down regulated by AFB₁ treatment in DT birds and pathway analysis suggested suppression of enteroendocrine cells. Conversely, AFB₁ treatment modified significantly fewer unique genes in EW birds; among these were genes involved in lipid synthesis and metabolism and immune response. This is the first investigation of the effects of AFB₁ on the turkey gastro-intestinal tract. Results suggest that in addition to the hepatic transcriptome, animal resistance to this mycotoxin occurs in organ systems outside the liver, specifically as a refractory gastrointestinal tract.

The Impact of Dietary Grape Seed Meal on Healthy and Aflatoxin B1 Afflicted Microbiota of Pigs after Weaning

The study investigated the effect of grape seed (GS) meal, aflatoxin (AFB1), or their combination on the large intestine microbiota of weanling piglets. Twenty-four piglets were allocated into four groups based on diet composition: (1) Control group; (2) AFB1 (320 g/kg feed) group; (3) GS group (8% inclusion in the diet); (4) AFB1 + GS group. After 30 days of experiment, the colon content was used for microbiota analyses; after isolation of total bacterial genomic DNA, V3/V4 regions of the 16S rRNA amplicons were sequenced using the Illumina MiSeq platform. The raw sequences were analyzed using the v.1.9.1 QIIME pipeline software. 157 numbers of OTUs were identified among all four dietary groups with 26 of them being prevalent above 0.05% in the total relative abundance. GS and AFB1 increase the relative abundance of phylum Bacteroidetes and Proteobacteria, while decreasing the Firmicutes abundance in a synergic manner as compared with the individual treatments. An additive or synergistic action of the two treatments was identified for Lactobacillus, Prevotella and Campylobacter, while rather an antagonistic effect was observed on Lachnospira. The action mechanisms of aflatoxin B1 and grape seed meal that drive the large intestine microbiota to these changes are not known and need further investigations.

Novel approaches for chemical and microbiological shelf life extension of cereal crops

Economic losses due to post-harvest fungal spoilage and mycotoxin contamination of cereal crops is a frequently encountered issue. Typically, chemical preservatives are used to reduce the initial microbial load and the environmental conditions during storage are controlled to prevent microbial growth. However, in recent years the consumers' desire for more naturally produced foods containing less chemical preservatives has grown increasingly stronger. This article reviews the latest advances in terms of novel approaches for chemical decontamination, namely application cold atmospheric pressure plasma and electrolyzed water, and their suitability for preservation of stored cereal crops. In addition, the alternative use of bio-preservatives, such as starter cultures or purified antimicrobial compounds, to prevent the growth of spoilage organisms or remove in-field accumulated mycotoxins is evaluated. All treatments assessed here show potential for inhibition of microbial spoilage. However, each method encounters draw-backs, making industrial application difficult. Even under optimized processing conditions, it is unlikely that one single treatment can reduce the natural microbial load sufficiently. It is evident that future research needs to examine the combined application of several treatments to exploit their synergistic properties. This would enable sufficient reduction in the microbial load and ensure microbiological safety of cereal crops during long-term storage.

Effect of probiotics on patulin removal from synbiotic apple juice

BACKGROUND

Studies have reported the occurrence of the mycotoxin patulin in apple products. The aim of this study was to produce synbiotic apple juice and investigate the detoxification of patulin by Lactobacillus acidophilus and Lactobacillus plantarum as probiotic strains. The impact of seven process variables on efficiency of toxin removal was investigated using Plackett-Burman design and presence of the surface-layer proteins as binding site of probiotics to patulin was confirmed during 6 weeks of cold storage.

RESULTS

Results showed that the removal of patulin by probiotic bacteria from apple juice depends significantly (P < 0.05) on the fructooligosaccharide content (as a prebiotic), concentration of patulin and the addition of ascorbic acid. Sodium dodecyl sulfate polyacrylamide gel electrophoresis of cell surface proteins of probiotic strains revealed that surface layer proteins have an important role in patulin removal from apple juice. In the best conditions, 91.23% of initial patulin concentration was removed from juice during 6 weeks refrigerated storage. No significant difference was observed in organoleptic properties of the synbiotic apple juice and raw sample.

CONCLUSION

In the best condition reported in this study, contaminated synbiotic apple juice by patulin will be safe for consumers after the first day of probiotic inoculation. © 2016 Society of Chemical Industry.

Dairy Propionibacteria: Versatile Probiotics

Dairy propionibacteria are used as cheese ripening starters, as biopreservative and as beneficial additives, in the food industry. The main species, Propionibacterium freudenreichii, is known as GRAS (Generally Recognized As Safe, USA, FDA). In addition to another dairy species, Propionibacterium acidipropionici, they are included in QPS (Qualified Presumption of Safety) list. Additional to their well-known technological application, dairy propionibacteria increasingly attract attention for their promising probiotic properties. The purpose of this review is to summarize the probiotic characteristics of dairy propionibacteria reported by the updated literature. Indeed, they meet the selection criteria for probiotic bacteria, such as the ability to endure digestive stressing conditions and to adhere to intestinal epithelial cells. This is a prerequisite to bacterial persistence within the gut. The reported beneficial effects are ranked according to property’s type: microbiota modulation, immunomodulation, and cancer modulation. The proposed molecular mechanisms are discussed. Dairy propionibacteria are described as producers of nutraceuticals and beneficial metabolites that are responsible for their versatile probiotic attributes include short chain fatty acids (SCFAs), conjugated fatty acids, surface proteins, and 1,4-dihydroxy-2-naphtoic acid (DHNA). These metabolites possess beneficial properties and their production depends on the strain and on the growth medium. The choice of the fermented food matrix may thus determine the probiotic properties of the ingested product. This review approaches dairy propionibacteria, with an interest in both technological abilities and probiotic attributes.

Antifungal Activity and Aflatoxin Degradation of Bifidobacterium Bifidum and Lactobacillus Fermentum Against Toxigenic Aspergillus Parasiticus

Food and feedstuff contamination with aflatoxins (AFTs) is a serious health problem for humans and animals, especially in developing countries. The present study evaluated antifungal activities of two lactic acid bacteria (LAB) against growth and aflatoxin production of toxigenic Aspergillus parasiticus. The mycelial growth inhibition rate of A. parasiticus PTCC 5286 was investigated in the presence of Bifidobacterium bifidum PTCC 1644 and Lactobacillus fermentum PTCC 1744 by the pour plate method. After seven days incubation in yeast extract sucrose broth at 30°C, the mycelial mass was weighed after drying. The inhibitory activity of LAB metabolites against aflatoxin production by A. parasiticus was evaluated using HPLC method. B. bifidum and L. fermentum significantly reduced aflatoxin production and growth rate of A. parasiticus in comparison with the controls (p≤0.05). LAB reduced total aflatoxins and B₁, B₂, G₁ and G₂ fractions by more than 99%. Moreover, LAB metabolites reduced the level of standard AFB₁, B₂, G₁ and G₂ from 88.8% to 99.8% (p≤0.05). Based on these findings, B. bifidum and L. fermentum are recommended as suitable biocontrol agents against the growth and aflatoxin production by aflatoxigenic Aspergillus species.

Immuno-physiological alterations from AFB1 in rats counteracted by treatments with Lactobacillus paracasei BEJ01 and montmorillonite clay mixture

High contamination by aflatoxin B1 (AFB1) has been detected in Beja province (Tunisia) in many dairy products and animal feed, which has resulted in many tons of cereals and cereals being removed from the market, causing economic loss. While removal represents a means of reducing risk, exposures still occur. Studies have increasingly focused on means of AFB1 biodegradation/elimination using lactic acid bacteria and clay mineral. In the study here, Lactobacillus paracasei BEJ01 (LP) and montmorilonite clay (MT) were used to reduce the physio-/immunotoxicologic disorders that could develop in rats that underwent AFB1 exposures for a total of 7 consecutive days. The results indicated that rats treated with AFB1 (80 μg/kg BW) alone had significant decreases in lymphocytes in their blood (including B-lymphocytes, CD3(+), CD4(+), and CD8(+) T-lymphocyte subtypes, and NK cells), immunoglobulins (IgA and IgG) and pro-inflammatory cytokines; these rats also had altered oxidative stress status. In contrast, in rats treated with LP + MT (2 × 10(9) cfu/ml [∼ 2 mg/kg] + 0.5 mg MT/kg BW) for a total of 7 days before, concurrent with or after AFB1 treatment, there was a significant blockade/mitigation of each AFB1-impacted parameter. Moreover, treatment with the mixture at any point in relation to AFB1 treatment expectedly caused enhanced TNFα and IL-1β expression relative to control values; all other parameters were comparable to values noted in control rats. Alone, the mixture had no impact on host parameters. From the results here it may be concluded the the LP + MT mixture was effective in protecting these hosts against AFB1-induced immunologic/physiologic disorders and that LP + MT could prevent and/or mitigate AFB1 toxicities in vivo.

In vitro ability of beer fermentation residue and yeast-based products to bind aflatoxin B1

This study aimed to verify the in vitro ability of beer fermentation residue (BFR) containing Saccharomyces cerevisiae cells and five commercial products that differed in the viability and integrity of S. cerevisiae cells to remove aflatoxin B₁ (AFB₁) from a citrate-phosphate buffer solution (CPBS). BFR was collected at a microbrewery and prepared by drying and milling. The commercial yeast-based products were as follows: inactive intact yeast cells from beer alcoholic fermentation, inactive intact yeast cells from sugarcane alcoholic fermentation, hydrolyzed yeast cells, yeast cell walls and active yeast cells. Adsorption assays were performed in CPBS spiked with 1.0 μg AFB₁/mL at pH 3.0 and 6.0 for a contact time of 60 min at room temperature. Analysis of AFB₁ in the samples was performed by high performance liquid chromatography. AFB₁ adsorption by the products ranged from 45.5% to 69.4% at pH 3.0 and from 24.0% to 63.8% at pH 6.0. The higher percentages (p < 0.05) of AFB₁ binding at both pH values were achieved with products containing hydrolyzed yeast cells or yeast cell walls rather than intact cells. The AFB₁ binding percentages of BFR were 55.0 ± 5.0% at pH 3.0 and 49.2 ± 4.5% at pH 6.0, which was not significantly different (p > 0.05) from commercial products containing inactive intact yeast cells. The results of this trial indicate that the yeast-based products tested, especially the BFR, have potential applications in animal feeds as a suitable biological method for reducing the adverse effects of aflatoxins.

Modulation of the spleen transcriptome in domestic turkey (Meleagris gallopavo) in response to aflatoxin B1 and probiotics

Poultry are highly susceptible to the immunotoxic effects of the food-borne mycotoxin aflatoxin B1 (AFB1). Exposure impairs cell-mediated and humoral immunity, limits vaccine efficacy, and increases the incidence of costly secondary infections. We investigated the molecular mechanisms of AFB1 immunotoxicity and the ability of a Lactobacillus-based probiotic to protect against aflatoxicosis in the domestic turkey (Meleagris gallopavo). The spleen transcriptome was examined by RNA sequencing (RNA-seq) of 12 individuals representing four treatment groups. Sequences (6.9 Gb) were de novo assembled to produce over 270,000 predicted transcripts and transcript fragments. Differential expression analysis identified 982 transcripts with statistical significance in at least one comparison between treatment groups. Transcripts with known immune functions comprised 27.6 % of significant expression changes in the AFB1-exposed group. Short exposure to AFB1 suppressed innate immune transcripts, especially from antimicrobial genes, but increased the expression of transcripts from E3 ubiquitin-protein ligase CBL-B and multiple interleukin-2 response genes. Up-regulation of transcripts from lymphotactin, granzyme A, and perforin 1 could indicate either increased cytotoxic potential or activation-induced cell death in the spleen during aflatoxicosis. Supplementation with probiotics was found to ameliorate AFB1-induced expression changes for multiple transcripts from antimicrobial and IL-2-response genes. However, probiotics had an overall suppressive effect on immune-related transcripts.

Response of the hepatic transcriptome to aflatoxin B1 in domestic turkey (Meleagris gallopavo)

Dietary exposure to aflatoxin B₁ (AFB₁) is detrimental to avian health and leads to major economic losses for the poultry industry. AFB₁ is especially hepatotoxic in domestic turkeys (Meleagris gallopavo), since these birds are unable to detoxify AFB₁ by glutathione-conjugation. The impacts of AFB₁ on the turkey hepatic transcriptome and the potential protection from pretreatment with a Lactobacillus-based probiotic mixture were investigated through RNA-sequencing. Animals were divided into four treatment groups and RNA was subsequently recovered from liver samples. Four pooled RNA-seq libraries were sequenced to produce over 322 M reads totaling 13.8 Gb of sequence. Approximately 170,000 predicted transcripts were de novo assembled, of which 803 had significant differential expression in at least one pair-wise comparison between treatment groups. Functional analysis linked many of the transcripts significantly affected by AFB₁ exposure to cancer, apoptosis, the cell cycle or lipid regulation. Most notable were transcripts from the genes encoding E3 ubiquitin-protein ligase Mdm2, osteopontin, S-adenosylmethionine synthase isoform type-2, and lipoprotein lipase. Expression was modulated by the probiotics, but treatment did not completely mitigate the effects of AFB₁. Genes identified through transcriptome analysis provide candidates for further study of AFB₁ toxicity and targets for efforts to improve the health of domestic turkeys exposed to AFB₁.

Aflatoxicosis chemoprevention by probiotic Lactobacillius and lack of effect on the major histocompatibility complex

Turkeys are extremely sensitive to aflatoxin B1 (AFB1) which causes decreased growth, immunosuppression and liver necrosis. The purpose of this study was to determine whether probiotic Lactobacillus, shown to be protective in animal and clinical studies, would likewise confer protection in turkeys, which were treated for 11 days with either AFB1 (AFB; 1 ppm in diet), probiotic (PB; 1 × 10(11) CFU/ml; oral, daily), probiotic + AFB1 (PBAFB), or PBS control (CNTL). The AFB1 induced drop in body and liver weights were restored to normal in CNTL and PBAFB groups. Hepatotoxicity markers were not significantly reduced by probiotic treatment. Major histocompatibility complex (MHC) genes BG1 and BG4, which are differentially expressed in liver and spleens, were not significantly affected by treatments. These data indicate modest protection, but the relatively high dietary AFB1 treatment, and the extreme sensitivity of this species may reveal limits of probiotic-based protection strategies.

Effect of supplementing direct-fed microbials on broiler performance, nutrient digestibilities, and immune responses

Direct-fed microbials (DFM) are used to improve livestock health and performance. The effects of 2 DFM products, a blend of 3 Bacillus strains (DFMB) and a Propionibacteriumspp. (DFMP), on broiler performance, nutrient utilization, and immune responses were investigated. Day-old (n = 120) male broilers were divided into 24 groups of 5 birds and fed 3 wheat-based diets in mash form (8 groups per diet) from d 1 to 22. The control diet was fed without or with 7.5 × 10(4) cfu/g of either DFMB or DFMP. From d 19 to 21 fecal samples were collected for determination of total tract apparent retention (TTAR) of nutrients and AMEn. On d 21, feed intake and BW were determined. On d 22, 5 birds per treatment were killed by cervical dislocation to collect jejunal and ileal contents for determination of digesta viscosity and apparent ileal digestibility (AID) of nutrients, respectively, and ileum, cecal tonsil, and spleen tissues for Toll-like receptors (TLR) and cytokine expressions. Compared with the control, DFM did not affect BW gain and feed intake but DFMP reduced G:F (P < 0.01). Compared with the control (2,875 kcal/kg), birds fed on DFMB and DFMP had higher AMEn (2,979 and 2,916 kcal/kg, respectively; P < 0.05), whereas both DFM reduced the AID of DM (P < 0.001) and CP (P < 0.01). Furthermore, DFMP reduced TTAR of NDF (29.0 vs. 18.4%; P < 0.001), whereas both DFM increased TTAR of DM and fat (P < 0.001). Supplementing DFMP downregulated ileal expression of TLR-2b, IL-2, IL-4, IL-6, IL-10, and IL-13, whereas DFMB downregulated TLR-2b, IL-2, IL-4, and IL-6 in all 3 tissues, IL-10 in the spleen, and upregulated IL-13 in the spleen. In conclusion, the DFM did not improve performance but increased the AMEn of diet by possibly increasing DM and fat retention. Overall, both DFM showed an antiinflammatory effect in the ileum, but DFMB had more effects on local and systemic immunity than DFMP.

Reduction of aflatoxin level in aflatoxin-induced rats by the activity of probiotic Lactobacillus casei strain Shirota

AIMS

Aflatoxin B1 (AFB1 ) is considered as the most toxic food contaminant, and microorganisms, especially bacteria, have been studied for their potential to reduce the bioavailability of mycotoxins including aflatoxins. Therefore, this research investigated the efficacy of oral administration of Lactobacillus casei Shirota (LcS) in aflatoxin-induced rats.

METHODS AND RESULTS

Sprague Dawley rats were divided into three groups of untreated control, the group induced with AFB1 only, and the group given probiotic in addition to AFB1. In the group induced with AFB1 only, food intake and body weight were reduced significantly. The liver and kidney enzymes were significantly enhanced in both groups induced with AFB1 , but they were lower in the group given LcS. AFB1 was detected from all serum samples except for untreated control group's samples. Blood serum level of AFB1 in the group induced with AFB1 only was significantly higher than the group which received probiotic as a treatment (P < 0·05), and there was no significant difference between the control group and the group treated with probiotic.

CONCLUSIONS

LcS supplementation could improve the adverse effect of AFB1 induction on rats' body weight, plasma biochemical parameters and also could reduce the level of AFB1 in blood serum.

SIGNIFICANCE AND IMPACT OF THE STUDY

This study's outcomes contribute to better understanding of the potential of probiotic to reduce the bioavailability ofAFB1 . Moreover, it can open an opportunity for future investigations to study the efficacy of oral supplementation of probiotic LcS in reducing aflatoxin level in human.

Multifaceted attributes of dairy propionibacteria: a review

Dairy propionibacteria are Generally Recognized as Safe (GRAS) status microorganisms which have been traditionally used for the manufacture of Swiss type cheeses. In the last two decades various added features and functionalities have been discovered and developed from these bacteria. Propionibacteria are robust organisms with remarkable adaptability to technological and physiological stress conditions. Besides, they also display a multitude of health promoting properties like modulation of gut microbiota, improved gut physiology and immunomodulation suggesting their promising probiotic potential. Propionibacteria produce an interestingly wide range of functional biomolecules like B group vitamins, trehalose, conjugated linoleic acid, propionic acid, bacteriocins, bifidogenic factors etc. These bacteria are thus now being explored for designing novel functional foods as well as for industrial production of nutraceuticals. Growing interest in these bacteria is fueled by the first whole genome sequencing of a Propionibacterium freudenreichii strain providing a platform for better understanding of various pathways and further improvement in related process technologies.

Substances for reduction of the contamination of feed by mycotoxins: a review

The global occurrence of mycotoxins is considered to be a major risk factor for human and animal health. Contamination of different agricultural commodities with mycotoxins still occurs despite the most strenuous prevention efforts. As a result, mycotoxin contaminated feed can cause serious disorders and diseases in farm animals. A number of approaches, such as physical and chemical detoxification procedures, have been used to counteract mycotoxins. However, only a few of them have practical application. A recent and promising approach to protect animals against the harmful effects of mycotoxin contaminated feed is the use of substances for reduction of the contamination of feed by mycotoxins. These substances, so-called mycotoxin binders (MB), are added to the diet in order to reduce the absorption of mycotoxins from the gastrointestinal tract and their distribution to blood and target organs, thus preventing or reducing mycotoxicosis in livestock. Recently, the use of such substances as technological feed additives has been officially allowed in the European Union. The efficacy of MB appears to depend on the properties of both the binder and the mycotoxin. Depending on their mode of action, these feed additives may act either by binding mycotoxins to their surface (adsorption), or by degrading or transforming them into less toxic metabolites (biotransformation). Biotransformation can be achieved by mycotoxin-degrading enzymes or by microorganisms producing such enzymes. Various inorganic adsorbents, such as hydrated sodium calcium aluminosilicate, zeolites, bentonites, clays, and activated carbons, have been tested and used as MB. An interesting alternative to inorganic adsorbents for the detoxification of mycotoxins is the use of organic binders, such as yeast cell wall components, synthetic polymers (cholestyramine, polyvinylpyrrolidone), humic substances and dietary fibres. This paper gives an overview of the current knowledge and situation in the field of MB. The most important types of MB, mechanism of their action, and their application as a part of general strategy to counteract mycotoxins are described in this review. Recent advances in the use and study of MB, as well as data of their in vitro and in vivo effectiveness are given. Problems, potential, current trends and perspectives associated with the use of MB are discussed as well in the review.

Effect of oral supplementation of Lactobacillus reuteri in reduction of intestinal absorption of aflatoxin B(1) in rats

The goals of this work were to assess the ability of Lactobacillus reuteri to bind aflatoxin B(1) in the intestinal tract and determine its effect on intestinal absorption of the toxin dispensed in either single or multiple doses in a murine model. Male Wistar rats were used, and two experiments were conducted after bacteria were implanted. Experiment one involved a single-oral dose of toxin, and the subsequent flow cytometric analysis of bacteria isolated from the small intestine and treated with specific FITC-labeled AFB(1) antibodies. The second experiment was carried out supplying the toxin in 7 oral sub-doses, and the later quantification of AFB(1)-Lys adducts in blood samples by ELISA assay. The results demonstrated that L. reuteri was able to bind AFB(1) in the intestinal tract, mostly in the duodenum. Furthermore, the AFB(1)-Lys adducts were present at significantly lower levels in those animals receiving AFB(1) plus bacteria than in those receiving only AFB(1). Our findings confirm that probiotic bacteria could act as biological barriers in normal intestinal conditions thereby reducing the bioavailability of AFB(1) ingested orally in a single or multiple doses, thus avoiding its toxic effects.

Detoxification of aflatoxin B1 by certain bacterial species isolated from Egyptian soil

Aflatoxin contamination of food and grain poses a serious economic and health problem worldwide. Aflatoxin B1 (AFB1) is extremely mutagenic, toxic and a potent carcinogen to both humans and livestock. A safe, effective and environmentally sound detoxification method is needed for controlling this toxin. In this study, 21 soil samples were screened from various sources with vast microbial populations using a coumarin containing medium. Eleven bacterial isolates showing AFB1 reduction activity in a liquid culture medium were selected from the screening experiments. Isolate 12-3 and 12-5, obtained from soil samples of Kafr-Zaiat Pesticide company drainage and identified to be Pseudomonas putida and Escherichia coli, reduced AFB1 by 69.3% and 58.8%, respectively, after incubation in the liquid medium at 37 °C for 72 h. The culture supernatant of these isolates was able to reduce AFB1 effectively by 76.2% and 62.5%, respectively, whereas the viable cells and cell extracts were far less effective. Factors influencing AFB1 detoxification by the culture supernatant were investigated. The highest detoxification activity for P. putida and E. coli was 83.3% and 63.8%, respectively, at pH 8 and 30 °C for 72 h. The detoxification activity was reduced at 10, 20 and 45 °C. The Mg2+, Mn2+, Se and Cu2+ ions were activators for AFB1 detoxification. However, Zn2+ ion was a strong inhibitor. Treatments with proteinase K, proteinase K plus SDS and heating significantly reduced or eradicated the detoxification activity of the culture supernatant. In conclusion, the detoxification of AFB1 by P. putida 12-3 was enzymatic and the enzymes responsible for the detoxification of AFB1 are constitutively extracellular produced. Also, the AFB1 detoxification by E. coli was conducted by enzymes as well as by cell wall binding mechanism. Both bacteria could have great potential in industrial applications.

Microbial strategies to control aflatoxins in food and feed

Aflatoxins are a group of toxic and carcinogenic fungal metabolites. They are commonly found in cereals, nuts and animal feeds and create a significant threat to the food industry and animal production. Several strategies have been developed to avoid or reduce harmful effects of aflatoxins since the 1960s. However, prevention of aflatoxin contamination pre/post harvest or during storage has not been satisfactory and control strategies such as physical removing and chemical inactivating used in food commodities have their deficiencies, which limit their large scale application. It is expected that progress in the control of aflatoxin contamination will depend on the introduction of technologies for specific, efficient and environmentally sound detoxification. The utilisation of biological detoxification agents, such as microorganisms and/or their enzymatic products to detoxify aflatoxins in contaminated food and feed can be a choice of such technology. To date, many of the microbial strategies have only showed reduced concentration of aflatoxins and the structure and toxicity of the detoxified products are unclear. More attention should be paid to the detoxification reactions, the structure of biotransformed products and the enzymes responsible for the detoxification. In this article, microbial strategies for aflatoxin control such as microbial binding and microbial biotransformation are reviewed.

In vitro efficacy of Myxococcus fulvus ANSM068 to biotransform aflatoxin B₁

Aflatoxin B₁ (AFB₁) is commonly found in cereals and animal feeds and causes a significant threat to the food industry and animal production. Several microbial isolates with high AFB₁ transformation ability have been identified in our previous studies. The aim of this research was to characterize one of those isolates, Myxococcus fulvus ANSM068, and to explore its biotransformation mechanism. The bacterial isolate of M. fulvus ANSM068, isolated from deer feces, was able to transform AFB₁ by 80.7% in liquid VY/2 medium after incubation at 30 °C for 72 h. The supernatant of the bacterial culture was more effective in transforming AFB₁ as compared to the cells alone and the cell extract. The transformation activity was significantly reduced and eradicated after the culture supernatant was treated with proteinase K, proteinase K plus SDS and heating. Culture conditions, including nitrogen source, initial pH and incubation temperature were evaluated for an optimal AFB₁ transformation. Liquid chromatography mass spectrometry (LCMS) analyses showed that AFB₁ was transformed to a structurally different compound. Infrared analysis (IR) indicated that the lactone ring on the AFB₁ molecule was modified by the culture supernatant. Chromatographies on DEAE-Ion exchange and Sephadex-Molecular sieve and SDS-PAGE electrophoresis were used to determine active components from the culture supernatant, indicating that enzyme(s) were responsible for the AFB₁ biotransformation. This is the first report on AFB₁ transformation by a strain of myxobacteria through enzymatic reaction(s).

Screening of Lactobacillus casei strains for their ability to bind aflatoxin B1

It has been proposed that the consumption of lactic acid bacteria capable of binding or degrading foodborne carcinogens would reduce human exposure to these deleterious compounds. In the present study, the ability of eight strains of Lactobacillus casei to bind aflatoxin B1 in aqueous solution was investigated. Additionally, the effect of addition of bile salts to the growth medium on aflatoxin B1 binding was assessed. The eight strains tested were obtained from different ecological niches (cheese, corn silage, human feces, fermented beverage). The strains exhibited different degrees of aflatoxin binding; the strain with the highest AFB1 binding was L. casei L30, which bound 49.2% of the available aflatoxin (4.6 microg/mL). In general, the human isolates bound the most aflatoxin B1 and the cheese isolates the least. Stability of the bacterial-aflatoxin complex was assessed by repeated washings. Binding was to a limited degree (0.6-9.2% release) reversible; the L. casei 7R1-aflatoxin B1 complex exhibited the greatest stability. L. casei L30, a human isolate, was the strain least sensitive to the inhibitory effects of bile salts. Exposure of the bacterial cells to bile significant increased aflatoxin B1 binding and the differences between the strains was reduced.