Toxicity, biodegradation, and nutritional intervention mechanism of zearalenone

Zearalenone (ZEA), a global mycotoxin commonly found in a variety of grain products and animal feed, causes damage to the gastrointestinal tract, immune organs, liver and reproductive system. Many treatments, including physical, chemical and biological methods, have been reported for the degradation of ZEA. Each degradation method has different degradation efficacies and distinct mechanisms. In this article, the global pollution status, hazard and toxicity of ZEA are summarized. We also review the biological detoxification methods and nutritional regulation strategies for alleviating the toxicity of ZEA. Moreover, we discuss the molecular detoxification mechanism of ZEA to help explore more efficient detoxification methods to better reduce the global pollution and hazard of ZEA.

Relevant mycotoxins in oil crops, vegetable oils, de-oiled cake and meals: Occurrence, control, and recent advances in elimination

Mycotoxins in agricultural commodities have always been a concern due to their negative impacts on human and livestock health. Issues associated with quality control, hot and humid climate, improper storage, and inappropriate production can support the development of fungus, causing oil crops to suffer from mycotoxin contamination, which in turn migrates to the resulting oil, de-oiled cake and meals during the oil processing. Related research which supports the development of multi-mycotoxin prevention programs has resulted in satisfactory mitigation effects, mainly in the pre-harvest stage. Nevertheless, preventive actions are unlikely to avoid the occurrence of mycotoxins completely, so removal strategies may still be necessary to protect consumers. Elimination of mycotoxin has been achieved broadly through the physical, biological, or chemical course. In view of the steadily increasing volume of scientific literature regarding mycotoxins, there is a need for ongoing integrated knowledge systems. This work revisited the knowledge of mycotoxins affecting oilseeds, food oils, cake, and meals, focusing more on their varieties, toxicity, and preventive strategies, including the methods adopted in the decontamination, which supplement the available information.

The Motion Paradigm of Pre-Dock Zearalenone Hydrolase Predictions with Molecular Dynamics and the Docking Phase with Umbrella Sampling

Zearalenone (ZEN) is one of the most prevalent estrogenic mycotoxins, is produced mainly by the Fusarium family of fungi, and poses a risk to the health of animals. Zearalenone hydrolase (ZHD) is an important enzyme capable of degrading ZEN into a non-toxic compound. Although previous research has investigated the catalytic mechanism of ZHD, information on its dynamic interaction with ZEN remains unknown. This study aimed to develop a pipeline for identifying the allosteric pathway of ZHD. Using an identity analysis, we identified hub genes whose sequences can generalize a set of sequences in a protein family. We then utilized a neural relational inference (NRI) model to identify the allosteric pathway of the protein throughout the entire molecular dynamics simulation. The production run lasted 1 microsecond, and we analyzed residues 139-222 for the allosteric pathway using the NRI model. We found that the cap domain of the protein opened up during catalysis, resembling a hemostatic tape. We used umbrella sampling to simulate the dynamic docking phase of the ligand-protein complex and found that the protein took on a square sandwich shape. Our energy analysis, using both molecular mechanics/Poisson-Boltzmann (Generalized-Born) surface area (MMPBSA) and Potential Mean Force (PMF) analysis, showed discrepancies, with scores of -8.45 kcal/mol and -1.95 kcal/mol, respectively. MMPBSA, however, obtained a similar score to that of a previous report.

Roles of stress response-related signaling and its contribution to the toxicity of zearalenone in mammals

Zearalenone (ZEA) is a mycotoxin frequently found in cereal crops and cereal-derived foodstuffs worldwide. It affects plant productivity, and is also a serious hazard to humans and animals if being exposed to food/feed contaminated by ZEA. Studies over the last decade have shown that the toxicity of ZEA in animals is mainly mediated by the various stress responses, such as endoplasmic reticulum (ER) stress, oxidative stress, and others. Accumulating evidence shows that oxidative stress and ER stress signaling are actively implicated in and contributes to the pathophysiology of various diseases. Biochemically, the deleterious effects of ZEA are associated with apoptosis, DNA damage, and lipid peroxidation by regulating the expression of genes implicated in these biological processes. Despite these findings, the underlying mechanisms responsible for these alterations remain unclear. This review summarized the characteristics, metabolism, toxicity and the deleterious effects of ZEA exposure in various tissues of animals. Stress response signaling implicated in the toxicity as well as potential therapeutic options with the ability to reduce the deleterious effects of ZEA in animals were highlighted and discussed.

Microbial and enzymatic battle with food contaminant zearalenone (ZEN)

Zearalenone (ZEN) contamination of various foods and feeds is an important global problem. In some animals and humans, ZEN causes significant health issues in addition to massive economic losses, annually. Therefore, removal or degradation of the ZEN in foods and feeds is required to be done. The conventional physical and chemical methods have some serious issues including poor efficiency, decrease in nutritional value, palatability of feed, and use of costly equipment. Research examined microbes from diverse media for their ability to degrade zearalenone and other toxins, and the findings of several investigations revealed that enzymes produced from microbes play a significant role in the degradation of mycotoxins. In established bacterial hosts, genetically engineered technique was used to enhance heterologously produced degrading enzymes. Then, the bio-degradation of ZEN by the use of micro-organisms or their enzymes is much more advantageous and is close to nature and ecofriendly. Furthermore, an effort is made to put forward the work done by different scientists on the biodegradation of ZEN by the use of fungi, yeast, bacteria, and/or their enzymes to degrade the ZEN to non-toxic products. KEY POINTS: •Evolved microbial strains degraded ZEA more quickly •Different degrading properties were studied.

Zearalenone toxicosis on reproduction as estrogen receptor selective modulator and alleviation of zearalenone biodegradative agent in pregnant sows

BACKGROUND

Zearalenone (ZEA) is a resorcylic acid lactone derivative derived from various Fusarium species that are widely found in food and feeds. The molecular structure of ZEA resembles that of the mammalian hormone 17β-oestradiol, thus zearalenone and its metabolites are known to compete with endogenous hormones for estrogen receptors binding sites and to activate transcription of oestrogen-responsive genes. However, the effect of long-term low-dose ZEA exposure on the reproductive response to Bacillus subtilis ANSB01G culture for first-parity gilts has not yet been investigated. This study was conducted to investigate the toxic effects of ZEA as an estrogen receptor selective modulator and the alleviating effects of Bacillus subtilis ANSB01G cultures as ZEA biodegraders in pregnant sows during their first parity.

RESULTS

A total of 80 first-parity gilts (Yorkshire × Landrace) were randomly assigned to four dietary treatments during gestation: CO (positive control); MO (negative control, 246 μg ZEA/kg diet); COA (CO + B. subtilis ANSB01G culture with 2 × 10⁹ CFU/kg diet); MOA (MO + B. subtilis ANSB01G culture with 2 × 10⁹ CFU/kg diet). There were 20 replications per treatment with one gilt per replicate. Feeding low-dose ZEA naturally contaminated diets disordered most of reproductive hormones secretion and affected estrogen receptor-α and estrogen receptor-β concentrations in serum and specific organs and led to moderate histopathological changes of gilts, but did not cause significant detrimental effects on reproductive performance. The addition of Bacillus subtilis ANSB01G culture to the diet can effectively relieve the competence of ZEA to estrogen receptor and the disturbance of reproductive hormones secretion, and then ameliorate toxicosis of ZEA in gilts.

CONCLUSIONS

Collectively, our study investigated the effects of feeding low-dose ZEA on reproduction in pregnant sows during their first parity. Feeding low-dose ZEA could modulate estrogen receptor-α and -β concentrations in specific organs, cause disturbance of reproductive hormones and vulva swelling, and damage organ histopathology and up-regulate apoptosis in sow models. Diet with Bacillus subtilis ANSB01G alleviated negative effects of the ZEA on gilts to some extent.

Screening of Pig-Derived Zearalenone-Degrading Bacteria through the Zearalenone Challenge Model, and Their Degradation Characteristics

Zearalenone (ZEN) is widely found in food and feed. Its cytotoxicity, reproductive toxicity, genetic toxicity, immunotoxicity and hepatorenal toxicity have serious impacts on human and animal health. In order to help animals avoid ZEN poisoning in feed, ZEN-degrading bacterial strains were screened from fecal samples through a zearalenone challenge pig model, and their degradation characteristics were researched. Through the optimization of parameters such as the culture time, pH value, temperature, and strain concentration, the optimal conditions for the ZEN-degrading ability of these strains were preliminarily determined, and the active site of the ZEN degradation was explored. In this study, three strains (SY-3, SY-14, SY-20) with high ZEN degradation capacities were obtained. SY-3 was identified as Proteus mirabilis, and its main degrading component was the supernatant. SY-14 and SY-20 were identified as Bacillus subtilis. Their main degrading components were the intracellular fluid of SY-14, and the intracellular fluid and cell wall of SY-20. The above results showed that the ZEN challenge model was an effective way to screen ZEN-degrading bacteria.

The Antagonistic Effect of Glutamine on Zearalenone-Induced Apoptosis via PI3K/Akt Signaling Pathway in IPEC-J2 Cells

Zearalenone (ZEN) is a non-steroidal estrogen mycotoxin produced by Fusarium fungi, which inevitably exists in human and animal food or feed. Previous studies indicated that apoptosis seems to be a key determinant of ZEN-induced toxicity. This experiment aimed to investigate the protective effects of Glutamine (Gln) on ZEN-induced cytotoxicity in IPEC-J2 cells. The experimental results showed that Gln was able to alleviate the decline of cell viability and reduce the production of reactive oxygen species and calcium (Ca²⁺) induced by ZEN. Meanwhile, the mRNA expression of antioxidant enzymes such as glutathione reductase, glutathione peroxidase, and catalase was up-regulated after Gln addition. Subsequently, Gln supplementation resulted in the nuclear fission and Bad-fluorescence distribution of apoptotic cells were weakened, and the mRNA expression and protein expression of pro-apoptotic genes and apoptotic rates were significantly reduced. Moreover, ZEN reduced the phosphorylation Akt, decreased the expression of Bcl-2, and increased the expression of Bax. Gln alleviated the above changes induced by ZEN and the antagonistic effects of Gln were disturbed by PI3K inhibitor (LY294002). To conclude, this study revealed that Gln exhibited significant protective effects on ZEN-induced apoptosis, and this effect may be attributed to the PI3K/Akt signaling pathway.

Comparison of Ameliorative Effects between Probiotic and Biodegradable Bacillus subtilis on Zearalenone Toxicosis in Gilts

This study was conducted to compare the potential ameliorative effects between probiotic Bacillus subtilis and biodegradable Bacillus subtilis on zearalenone (ZEN) toxicosis in gilts. Thirty-six Landrace×Yorkshire gilts (average BW = 64 kg) were randomly divided into four groups: (1) Normal control diet group (NC) fed the basal diet containing few ZEN (17.5 μg/kg); (2) ZEN contaminated group (ZC) fed the contaminated diet containing an exceeded limit dose of ZEN (about 300 μg/kg); (3) Probiotic agent group (PB) fed the ZC diet with added 5 × 10⁹ CFU/kg of probiotic Bacillus subtilis ANSB010; (4) Biodegradable agent group (DA) fed the ZC diet with added 5 × 10⁹ CFU/kg of biodegradable Bacillus subtilis ANSB01G. Results showed that Bacillus subtilis ANSB010 and ANSB01G isolated from broiler intestinal chyme had similar inhibitory activities against common pathogenic bacteria. In addition, the feed conversion ratio and the vulva size in DA group were significantly lower than ZC group (p < 0.05). The levels of IgG, IgM, IL-2 and TNFα in the ZC group were significantly higher than PB and DA groups (p < 0.05). The levels of estradiol and prolactin in the ZC group was significantly higher than those of the NC and DA groups (p < 0.05). Additionally, the residual ZEN in the feces of the ZC and PB groups were higher than those of the NC and DA groups (p < 0.05). In summary, the ZEN-contaminated diet had a damaging impact on growth performance, plasma immune function and hormone secretion of gilts. Although probiotic and biodegradable Bacillus subtilis have similar antimicrobial capacities, only biodegradable Bacillus subtilis could eliminate these negative effects through its biodegradable property to ZEN.

Biological Transformation of Zearalenone by Some Bacterial Isolates Associated with Ruminant and Food Samples

Zearalenone (ZEA) is a secondary metabolite produced by Fusarium spp., the filamentous fungi. Food and feed contamination with zearalenone has adverse effects on health and economy. ZEA degradation through microorganisms is providing a promising preventive measure. The current study includes isolation of 47 bacterial strains from 100 different food and rumen samples. Seventeen isolates showed maximum activity of ZEA reduction. A bacterial isolate, RS-5, reduced ZEA concentration up to 78.3% through ELISA analysis and 74.3% as determined through HPLC. Ten of the most efficient strains were further selected for comparison of their biodegradation activity in different conditions such as incubation period, and different growth media. The samples were analyzed after 24 h, 48 h, and 72 h of incubation. De Man Rogosa Sharp (MRS) broth, Tryptic soy broth, and nutrient broth were used as different carbon sources for comparison of activity through ELISA. The mean degradation % ± SD through ELISA and HPLC were 70.77% ± 3.935 and 69.11% ± 2.768, respectively. Optimum reducing activity was detected at 72 h of incubation, and MRS broth is a suitable medium. Phylogenetic analysis based on 16S rRNA gene nucleotide sequences confirmed that one of the bacterial isolate RS-5 bacterial isolates with higher mycotoxin degradation is identified as Bacillus subtilis isolated from rumen sample. B05 (FSL-8) bacterial isolate of yogurt belongs to the genus Lactobacillus with 99.66% similarity with Lactobacillus delbrukii. Similarly, three other bacterial isolates, D05, H05 and F04 (FS-17, FSL-2 and FS-20), were found to be the sub-species/strains Pseudomonas gessardii of genus Pseudomonas based on their similarity level of (99.2%, 96% and 96.88%) and positioning in the phylogenetic tree. Promising detoxification results were revealed through GC-MS analysis of RS-5 and FSL-8 activity.

New Biotransformation Mode of Zearalenone Identified in Bacillus subtilis Y816 Revealing a Novel ZEN Conjugate

An increasing number of Bacillus strains have been identified, and the removal capacity of zearalenone (ZEN) was determined; however, they failed to reveal the detoxification mechanism and transformation product. Here, Bacillus subtilis Y816, which could transform 40 mg/L of ZEN within 7 h of fermentation, was identified and studied. First, the biotransformation products of ZEN and 17-β-estradiol (E2) were identified as ZEN-14-phosphate and E2-3-phosphate by HPLC-TOF-MS and NMR, respectively. An intracellular zearalenone phosphotransferase (ZPH) was found through transcriptome sequencing analysis of B. subtilis Y816. The phosphorylated reaction conditions of ZEN by ZPH were further revealed in this work. Furthermore, the phosphorylated conjugates showed reduced estrogenic toxicity compared with their original substances (ZEN and α/β-zearalenol) using an engineered yeast biosensor system. The first report on the phosphorylated conjugated mode of ZEN in B. subtilis Y816 will inspire new perspectives on the biotransformation of ZEN in Bacillus strains.

Protective Effects of Bacillus subtilis ANSB060, Bacillus subtilis ANSB01G, and Devosia sp. ANSB714-Based Mycotoxin Biodegradation Agent on Mice Fed with Naturally moldy Diets

Mycotoxins are toxic secondary metabolites produced by toxigenic fungi that commonly contaminate agricultural crops. The purpose of the current study was to evaluate whether Bacillus subtilis ANSB060, Bacillus subtilis ANSB01G, and Devosia sp. ANSB714-based mycotoxin biodegradation agent (MBA) could alleviate the negative effects of naturally moldy diet containing aflatoxin (AF), zearalenone (ZEN), and deoxynivalenol (DON) on growth performance, serum immune function, and antioxidant capacity as well as tissue residues in mice. A total of 54 mice were randomly divided into three dietary treatments: basal diet (CON), multi-mycotoxins contaminated diet (MCD) containing AF, ZEN and DON and multi-mycotoxins contaminated diet plus MBA at a dose of 1.0 g kg^-1 feed (MCD + MBA). Mice fed with moldy diet showed a significant decrease in body weight gain (p < 0.05), whereas the relative weight of the liver, spleen and uterus were remarkably increased (p < 0.05). Serum IgA and IgM contents were significantly decreased in MCD treatment compared with that in CON treatment (p < 0.05). In contrast, serum interleukin-1β (IL-1β), interleukin-2 (IL-2), and interleukin-6 (IL-6) concentrations were significantly promoted in mice fed with moldy diet (p < 0.05). Besides, the exposure to mycotoxins caused marked down-regulation of serum superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) activities in mice (p < 0.05). The addition of MBA effectively counteracted these toxic effects of moldy diet on mice. And DON residues in kidneys of mice consuming moldy diet were eliminated by the supplementation with MBA. Taken together, Bacillus subtilis ANSB060, Bacillus subtilis ANSB01G, and Devosia sp. ANSB714-based mycotoxin biodegradation agent has great potential use as a microbial additive to counteract mycotoxins contamination in food and feed.

A Novel Microbial Zearalenone Transformation through Phosphorylation

Zearalenone (ZEA) is a mycotoxin widely occurring in many agricultural commodities. In this study, a purified bacterial isolate, Bacillus sp. S62-W, obtained from one of 104 corn silage samples from various silos located in the United States, exhibited activity to transform the mycotoxin ZEA. A novel microbial transformation product, ZEA-14-phosphate, was detected, purified, and identified by HPLC, LC-MS, and NMR analyses. The isolate has been identified as belonging to the genus Bacillus according to phylogenetic analysis of the 16S rRNA gene and whole genome alignments. The isolate showed high efficacy in transforming ZEA to ZEA-14-phosphate (100% transformation within 24 h) and possessed advantages of acid tolerance (work at pH = 4.0), working under a broad range of temperatures (22–42 °C), and a capability of transforming ZEA at high concentrations (up to 200 µg/mL). In addition, 23 Bacillus strains of various species were tested for their ZEA phosphorylation activity. Thirteen of the Bacillus strains showed phosphorylation functionality at an efficacy of between 20.3% and 99.4% after 24 h incubation, suggesting the metabolism pathway is widely conserved in Bacillus spp. This study established a new transformation system for potential application of controlling ZEA although the metabolism and toxicity of ZEA-14-phosphate requires further investigation.

Microbial detoxification of mycotoxins in food and feed

Mycotoxins are metabolites produced by fungi growing in food or feed, which can produce toxic effects and seriously threaten the health of humans and animals. Mycotoxins are commonly found in food and feed, and are of significant concern due to their hepatotoxicity, nephrotoxicity, carcinogenicity, mutagenicity, and ability to damage the immune and reproductive systems. Traditional physical and chemical detoxification methods to treat mycotoxins in food and feed products have limitations, such as loss of nutrients, reagent residues, and secondary pollution to the environment. Thus, there is an urgent need for new detoxification methods to effectively control mycotoxins and treat mycotoxin pollution. In recent years, microbial detoxification technology has been widely used for the degradation of mycotoxins in food and feed because this approach offers the potential for treatment with high efficiency, low toxicity, and strong specificity, without damage to nutrients. This article reviews the application of microbial detoxification technology for removal of common mycotoxins such as Aflatoxin, Ochratoxin, Zearalenone, Deoxynivalenol, and Fumonisins, and discusses the development trend of this important technology.

Mycotoxin and Gut Microbiota Interactions

The interactions between mycotoxins and gut microbiota were discovered early in animals and explained part of the differences in susceptibility to mycotoxins among species. Isolation of microbes present in the gut responsible for biotransformation of mycotoxins into less toxic metabolites and for binding mycotoxins led to the development of probiotics, enzymes, and cell extracts that are used to prevent mycotoxin toxicity in animals. More recently, bioactivation of mycotoxins into toxic compounds, notably through the hydrolysis of masked mycotoxins, revealed that the health benefits of the effect of the gut microbiota on mycotoxins can vary strongly depending on the mycotoxin and the microbe concerned. Interactions between mycotoxins and gut microbiota can also be observed through the effect of mycotoxins on the gut microbiota. Changes of gut microbiota secondary to mycotoxin exposure may be the consequence of the antimicrobial properties of mycotoxins or the toxic effect of mycotoxins on epithelial and immune cells in the gut, and liberation of antimicrobial peptides by these cells. Whatever the mechanism involved, exposure to mycotoxins leads to changes in the gut microbiota composition at the phylum, genus, and species level. These changes can lead to disruption of the gut barrier function and bacterial translocation. Changes in the gut microbiota composition can also modulate the toxicity of toxic compounds, such as bacterial toxins and of mycotoxins themselves. A last consequence for health of the change in the gut microbiota secondary to exposure to mycotoxins is suspected through variations observed in the amount and composition of the volatile fatty acids and sphingolipids that are normally present in the digesta, and that can contribute to the occurrence of chronic diseases in human. The purpose of this work is to review what is known about mycotoxin and gut microbiota interactions, the mechanisms involved in these interactions, and their practical application, and to identify knowledge gaps and future research needs.

Bacillus subtilis ANSB01G culture alleviates oxidative stress and cell apoptosis induced by dietary zearalenone in first-parity gestation sows

This study was conducted to evaluate the alleviation of Bacillus subtilis ANSB01G culture as zearalenone (ZEA) biodegradation agent on oxidative stress, cell apoptosis and fecal ZEA residue in the first parity gestation sows during the gestation. A total of 80 first-parity gilts (Yorkshire × Landrace) were randomly allocated to 4 dietary treatments with 20 replications per treatment and one gilt per replicate. The dietary treatments were as follows: CO (positive control); MO (negative control, ZEA level at 246 μg/kg diet); COA (CO + B. subtilis ANSB01G culture with 2 × 10⁹ CFU/kg diet); MOA (MO + ZEA level at 260 μg/kg diet + B. subtilis ANSB01G culture with 2 × 10⁹ CFU/kg diet). The experiment lasted for the whole gestation period of sows. Results showed that feeding the diet naturally contaminated with low-dose ZEA caused an increase of cell apoptosis in organ and the residual ZEA in feces as well as a decrease of antioxidant function in serum. The addition of B. subtilis ANSB01G culture in the diets can effectively alleviate the status of oxidative stress and cell apoptosis induced by ZEA in diets of gestation sows, as well as decrease the content of residual ZEA in feces.

Mycotoxin contamination and control strategy in human, domestic animal and poultry: A review

Mycotoxins are secondary metabolites produced mainly by fungi belonging to the genera Aspergillus, Fusarium, Penicillium, Claviceps, and Alternaria that contaminate basic food products throughout the world, where developing countries are becoming predominantly affected. Currently, more than 500 mycotoxins are reported in which the most important concern to public health and agriculture include AFB1, OTA, TCTs (especially DON, T-2, HT-2), FB1, ZEN, PAT, CT, and EAs. The presence of mycotoxin in significant quantities poses health risks varying from allergic reactions to death on both humans and animals. This review brings attention to the present status of mycotoxin contamination of food products and recommended control strategies for mycotoxin mitigation. Humans are exposed to mycotoxins directly through the consumption of contaminated foods while, indirectly through carryover of toxins and their metabolites into animal tissues, milk, meat and eggs after ingestion of contaminated feeds. Pre-harvest (field) control of mycotoxin production and post-harvest (storage) mitigation of contamination represent the most effective approach to limit mycotoxins in food and feed. Compared with chemical and physical approaches, biological detoxification methods regarding biotransformation of mycotoxins into less toxic metabolites, are generally more unique, productive and eco-friendly. Along with the biological detoxification method, genetic improvement and application of nanotechnology show tremendous potential in reducing mycotoxin production thereby improving food safety and food quality for extended shelf life. This review will primarily describe the latest developments in the formation and detoxification of the most important mycotoxins by biological degradation and other alternative approaches, thereby reducing the potential adverse effects of mycotoxins.

Characterization and Genome Analysis of a Zearalenone-Degrading Bacillus velezensis Strain ANSB01E

Zearalenone, a nonsteroidal estrogenic mycotoxin mainly produced by Fusarium species, causes reproductive disorders and hyperestrogenic syndromes in animals and humans. The bacterial strain Bacillus velezensis ANSB01E, isolated from chicken cecal content, was capable of effectively degrading zearalenone in both liquid medium and mouldy corn. Moreover, Bacillus velezensis ANSB01E exhibited good antimicrobial activities against animal pathogenic bacteria, including Escherichia coli, Staphylococcus aureus, and Salmonella spp. Genome-based analysis revealed the presence of genes coding peroxiredoxin and alpha/beta hydrolase in Bacillus velezensis ANSB01E, which may be involved in zearalenone degradation. The study on the genome provides insights into the zearalenone degradation mechanisms and advances the potential application of Bacillus velezensis ANSB01E in food and feed industry.

Biodetoxification of fungal mycotoxins zearalenone by engineered probiotic bacterium Lactobacillus reuteri with surface-displayed lactonohydrolase

Zearalenone (ZEN) is one of the common mycotoxins with quite high occurrence rate and is harmful to animal and human health. Lactobacillus reuteri is known as a probiotic bacterium with active immune stimulating and high inhibitory activity against pathogenic microorganisms. In this study, we expressed the lactonohydrolase from Rhinocladiella mackenziei CBS 650.93 (RmZHD) in L. reuteri via secretion and surface-display patterns, respectively. Endogenous signal peptides from L. reuteri were first screened to achieve high expression for efficient ZEN hydrolysis. For secretion expression, signal peptide from collagen-binding protein showed the best performance, while the one from fructose-2,6-bisphosphatase worked best for surface-display expression. Both of the engineered strains could completely hydrolyze 5.0 mg/L ZEN in 8 h without detrimental effects on bacterial growth. The acid and bile tolerance assay and anchoring experiment on Caco-2 cells indicated both of the abovementioned engineered strains could survive during digestion and colonize on intestinal tract, in which the surface-displayed strain had a better performance on ZEN hydrolysis. Biodetoxification of model ZEN-contaminated maize kernels showed the surface-displayed L. reuteri strain could completely hydrolyze 2.5 mg/kg ZEN within 4 h under low water condition. The strain could also efficiently detoxify natural ZEN-contaminated corn flour in the in vitro digestion model system. The colonized property, survival capacity, and the efficient hydrolysis performance as well as probiotic functionality make L. reuteri strain an ideal host for detoxifying residual ZEN in vivo, which shows a great potential for application in feed industry.

Zearalenone Biodegradation by the Combination of Probiotics with Cell-Free Extracts of Aspergillus oryzae and its Mycotoxin-Alleviating Effect on Pig Production Performance

In order to remove zearalenone (ZEA) detriment—Bacillus subtilis, Candida utilis, and cell-free extracts from Aspergillus oryzae were used to degrade ZEA in this study. The orthogonal experiment in vitro showed that the ZEA degradation rate was 92.27% (p < 0.05) under the conditions that Candida utilis, Bacillus subtilis SP1, and Bacillus subtilis SP2 were mixed together at 0.5%, 1.0%, and 1.0%. When cell-free extracts from Aspergillus oryzae were combined with the above probiotics at a ratio of 2:1 to make mycotoxin-biodegradation preparation (MBP), the ZEA degradation rate reached 95.15% (p < 0.05). In order to further investigate the MBP effect on relieving the negative impact of ZEA for pig production performance, 120 young pigs were randomly divided into 5 groups, with 3 replicates in each group and 8 pigs for each replicate. Group A was given the basal diet with 86.19 μg/kg ZEA; group B contained 300 μg/kg ZEA without MBP addition; and groups C, D, and E contained 300 μg/kg ZEA added with 0.05%, 0.10%, and 0.15% MBP, respectively. The results showed that MBP addition was able to keep gut microbiota stable. ZEA concentrations in jejunal contents in groups A and D were 89.47% and 80.07% lower than that in group B (p < 0.05), indicating that MBP was effective in ZEA biodegradation. In addition, MBP had no significant effect on pig growth, nutrient digestibility, and the relative mRNA abundance of estrogen receptor alpha (ERα) genes in ovaries and the uterus (p > 0.05).

Microbial reduction of zearalenone by a new isolated Lysinibacillus sp. ZJ-2016-1

Zearalenone (ZEA) has a strong reproductive toxicity. Reducing and eliminating ZEA from food and feed is of great significance. The aim of the present study was to screen bacteria for reduction of ZEA. A pure culture of strain ZJ-2016-1, identified as Lysinibacillus sp. by 16S rRNA gene sequence analysis methods, was isolated from chicken large intestine digesta and showed to be effective in eliminating ZEA; 32 μg/ml of ZEA in Luria-Bertani medium was completely removed within 48 h by whole cells of ZJ-2016-1. Heating treatment significantly reduced the removal rate of ZEA from 95.8 to 10.4% in the culture supernatant, suggesting that the microbial reduction of ZEA was likely enzymatic. The optimal conditions for the microbial reduction of ZEA by ZJ-2016-1 included temperature of 37 °C and pH of 7.0. To sum up, these results indicated that the Lysinibacillus strain is a promising bacterium resource for reducing ZEA, and its genes and enzymes involved in microbial reduction of ZEA should be further explored.

The application of digestive tract lactic acid bacteria with high esterase activity for zearalenone detoxification

BACKGROUND

Zearalenone (ZEA) is an estrogenic mycotoxin produced by several Fusarium species and frequently contaminates cereals used for food or animal feed. This study attempted to select lactic acid bacteria (LAB) with high esterase activity from the digestive tract, with the goal of using these bacteria for ZEA detoxification.

RESULTS

No ZEA activity-related biotransformation products were observed in three isolates (B1, B2 and D10) during incubation in the presence of ZEA. All three LAB strains were Lactobacillus plantarum, but the API 50 CHL results suggested that the three isolates were different strains. Increased esterase activity was associated with an increase in cell growth, and the ZEA-detoxifying capabilities of isolates rely on the concentration of bacteria in the culture medium. The lipolytic activity and ZEA removal assay indicated that ZEA degradation by the supernatant fraction was dependent on esterase activity; the supernatant of B2 strain showed the highest ZEA degradation ability and did not release the binding ZEA back into the medium. The D10 strain showed fast ZEA binding ability during the late log phase but began to release the bound ZEA back into the medium after the early stationary phase. All isolates showed good acid and bile salt tolerance ability but all strains showed low adhesion ability to epithelial cells.

CONCLUSION

Based on the ZEA removal characterization and ability of the isolates, it is suggested that the isolates could be applied to ZEA detoxification of contaminated feed, but the with the requirement of high cell number for ZEA binding and limited degradation time before absorption of ZEA in the digestive tract. © 2018 Society of Chemical Industry.

Alleviation of mycotoxin biodegradation agent on zearalenone and deoxynivalenol toxicosis in immature gilts

Background

The current study was carried out to evaluate the effects of mycotoxin biodegradation agent (MBA, composed of Bacillus subtilis ANSB01G and Devosia sp. ANSB714) on relieving zearalenone (ZEA) and deoxynivalenol (DON) toxicosis in immature gilts.

Methods

A total of forty pre-pubertal female gilts (61.42 ± 1.18 kg) were randomly allocated to four diet treatments: CO (positive control); MO (negative control, ZEA 596.86 μg/kg feed and DON 796 μg/kg feed); COA (CO + 2 g MBA/kg feed); MOA (MO + 2 g MBA/kg feed). Each treatment contained 10 replicates with 1 gilt per replicate. Gilts were housed in an environmentally controlled room with the partially slatted floor.

Results

During the entire experimental period of 28 d, average daily gain (ADG) and average daily feed intake (ADFI) of gilts in MO group was significantly reduced compared with those in CO group. The vulva size of gilts was significantly higher in MO group than CO group. In addition, significant increases in the plasma levels of IgA, IgG, IL-8, IL-10 and PRL were determined in MO group compared with that in CO group. ZEA and DON in the diet up-regulated apoptotic caspase-3 in ovaries and uteri, along with down-regulated the anti-apoptotic protein Bcl-2 in ovaries. The supplementation of MBA into diets co-contaminated with ZEA and DON significantly increased ADG, decreased the vulva sizes, reduced the levels of IgG, IL-8 and PRL in plasma, and regulated apoptosis in ovaries and uteri of gilts.

Conclusions

The present results indicated that feeding diet contaminated with ZEA and DON simultaneously (596.86 μg/kg + 796 μg/kg) had detrimental effects on growth performance, plasma immune function and reproductive status of gilts. And MBA could reduce the negative impacts of these two toxins, believed as a promising feed additive for mitigating toxicosis of ZEA and DON at low levels in gilts.

Strategies and Methodologies for Developing Microbial Detoxification Systems to Mitigate Mycotoxins

Mycotoxins, the secondary metabolites of mycotoxigenic fungi, have been found in almost all agricultural commodities worldwide, causing enormous economic losses in livestock production and severe human health problems. Compared to traditional physical adsorption and chemical reactions, interest in biological detoxification methods that are environmentally sound, safe and highly efficient has seen a significant increase in recent years. However, researchers in this field have been facing tremendous unexpected challenges and are eager to find solutions. This review summarizes and assesses the research strategies and methodologies in each phase of the development of microbiological solutions for mycotoxin mitigation. These include screening of functional microbial consortia from natural samples, isolation and identification of single colonies with biotransformation activity, investigation of the physiological characteristics of isolated strains, identification and assessment of the toxicities of biotransformation products, purification of functional enzymes and the application of mycotoxin decontamination to feed/food production. A full understanding and appropriate application of this tool box should be helpful towards the development of novel microbiological solutions on mycotoxin detoxification.

Review on biological degradation of mycotoxins

The worldwide contamination of feeds and foods with mycotoxins is a significant problem. Mycotoxins pose huge health threat to animals and humans. As well, mycotoxins bring enormous economic losses in food industry and animal husbandry annually. Thus, strategies to eliminate or inactivate mycotoxins in food and feed are urgently needed. Traditional physical and chemical methods have some limitations such as limited efficacy, safety issues, losses in the nutritional value and the palatability of feeds, as well as the expensive equipment required to implement these techniques. Biological degradation of mycotoxins has shown promise because it works under mild, environmentally friendly conditions. Aflatoxin (AF), zearalenone (ZEA) and deoxynivalenol (DON) are considered the most economically important mycotoxins in terms of their high prevalence and significant negative effects on animal performance. Therefore, this review will comprehensively describe the biological degradation of AF, ZEA and DON by microorganisms (including fungi and bacteria) and specific enzymes isolated from microbial systems that can convert mycotoxins with varied efficiency to non- or less toxic products. Finally, some strategies and advices on existing difficulties of biodegradation research are also briefly proposed in this paper.

Occurrence, prevention and remediation of toxigenic fungi and mycotoxins in silage: a review

Ruminants are considered to be less sensitive towards mycotoxins than monogastric animals because rumen microbiota have mycotoxin-detoxifying capacities. Therefore the effect of mycotoxins towards ruminants has been studied to a lesser extent compared with monogastric animals. Worldwide, a high proportion of the ruminant diet consists of silages made of forage crops (i.e. all parts of the crop above the stubble are harvested). In practice, silages are often contaminated with multiple mycotoxins. Exposure to a cocktail of mycotoxins can hamper animal production and have severe health consequences. In this article the different aspects associated with mycotoxin contamination of silage are reviewed 'from seed to feed'. An overview is given on the occurrence of toxigenic fungal species and their concomitant mycotoxins in forage crops before and after ensiling. The mycotoxin load of visually non-mouldy samples and mouldy hot spots within the same silo is also compared. Subsequently, this review delves into different problem-solving strategies. A logical first step is prevention of mould growth and mycotoxin production in the field, during harvest and during ensiling. If prevention should fail, several remediation strategies are available. These are listed, mainly focusing on the possibilities of microbial degradation of mycotoxins in vivo in silage. © 2015 Society of Chemical Industry.

The toxic effects of combined aflatoxins and zearalenone in naturally contaminated diets on laying performance, egg quality and mycotoxins residues in eggs of layers and the protective effect of Bacillus subtilis biodegradation product

The toxic effect of aflatoxins (AF) and zearalenone (ZEA) and their combination on laying performance, egg quality and toxins residues in eggs, as well as the efficacy of Bacillus subtilis biodegradation product (BDP) for ameliorating these effects in layers were evaluated. Layers were submitted to a two phase experiment. The first phase was an intoxication period (18-23 wk) with birds fed 7 (3 × 2 + 1) diets (3 treatments with mycotoxins: AF (123.0 μg/kg), ZEA (260.2 μg/kg), or AF + ZEA (123.0 + 260.2 μg/kg); 2 treatments with or without BDP (1000 g/t); and a control group contained no toxins nor BDP). The next phase was a recovery period (24-29 wk) in which birds were fed a toxin-free diet. In the intoxication period, AF and AF + ZEA groups exhibited lower egg production, feed intake and shell thickness, and higher AFB1, AFB2 and AFM1 residues as compared with the control group. In addition, AF and ZEA exerted synergistic effects on egg production and feed intake. Moreover, AF alone or combined with ZEA had a continuous toxic effect on laying performance in the recovery phase. Addition of BDP offset these negative effects, showing that BDP has a protective effect on layers fed contaminated diets.

Ameliorative effects of Bacillus subtilis ANSB01G on zearalenone toxicosis in pre-pubertal female gilts

The purpose of this research was to investigate the toxicity of zearalenone (ZEA) on the growing performance, genital organs, serum hormones and histopathological changes of pre-pubertal female gilts, and to evaluate the efficacy of Bacillus subtilis ANSB01G in alleviating ZEA toxicosis in gilts. Eighteen pre-pubertal female gilts were randomly allocated to three treatments with one replicate per treatment. The gilts were fed following three diets for 24 days: the Control group was given a basic diet with normal corn; Treatment 1 (T1) was prepared by substituting corn naturally contaminated with ZEA for all normal corn in the basic diet (with a final concentrations of 238.57 μg kg(-1) of ZEA); and Treatment 2 (T2) was prepared by mixing the T1 diet with 2 kg T(-1) of fermented-dried culture of ANSB01G. The results showed that the presence of ZEA in diets significantly increased the vulva size and reproductive organ weight of the T1 gilts as compared with the Control group, and the addition of ANSB01G to diet naturally contaminated with ZEA obviously ameliorated these symptoms, as was observed in the T2 group. The presence of low doses of ZEA in the T1 diet had no significant effect on the level of follicle-stimulating hormone (FSH), luteotrophic hormone (LH) or serum oestradiol (E2) in the serum of gilts, but the prolactin (PRL) level in group T1 increased significantly. The gilts of the T1 group exhibited conspicuous cell enlargement and fatty degeneration of the corpus uteri, swelling, inflammation and lymphocyte infiltration of liver cells as compared with the Control group. The presence of ANSB01G can alleviate these hyperoestrogenic effects caused by ZEA, maintaining the body of gilt in a normal and healthy status. It is suggested that reproductive organs of gilts are seriously affected even if they are fed a low dose of ZEA in less time, and the addition of B. subtilis ANSB01G can effectively alleviate ZEA toxicosis in gilts.