Detoxification of zearalenone by three strains of lactobacillus plantarum from fermented food in vitro

Toxins in Fermented Foods: Prevalence and Preventions-A Mini Review

Fermented foods (FF) are widely consumed around the world, and FF are one of the prime sources of toxins and pathogenic microbes that are associated with several foodborne outbreaks. Mycotoxins (aflatoxins, fumonisins, sterigmatocystin, nivalenol, deoxynivalenol, zearalenone, ochratoxin, and alternariol), bacterial toxins (shiga toxin and botulinum), biogenic amines, and cyanogenic glycosides are the common toxins found in FF in addition to the pathogenic microbes. Fermented milk products and meat sausages are extremely vulnerable to contamination. Cumulative updated information about a specific topic such as toxins in FF is essential for the improvement of safer preparation and consumption of fermented foods. Accordingly, the current manuscript summarizes the reported mycotoxins, bacterial toxins, and/or toxins from other sources; detection methods and prevention of toxins in FF (use of specific starter culture, optimized fermentation process, and pre- and post-processing treatments); and major clinical outbreaks. This literature survey was made in Scopus, Web of Science, NCBI-PubMed, and Google Scholar using the search terms "Toxins" and "Fermented Foods" as keywords. The appropriate scientific documents were screened for relevant information and they were selected without any chronological restrictions.

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.

Zearalenone reduction by commercial peroxidase enzyme and peroxidases from soybean bran and rice bran

The peroxidase (POD) enzyme, obtained from different sources, has been described in the literature regarding its good results of reduction in concentration or degradation levels of mycotoxins, such as aflatoxin B1, deoxynivalenol and zearalenone (ZEA). This study aimed at evaluating the action of commercial POD and POD from soybean bran (SB) and rice bran (RB) in ZEA reduction in a model solution and the characterisation of the mechanism of enzyme action. POD was extracted from SB and RB in phosphate buffer by orbital agitation. Evaluation of the action of commercial POD and POD from SB and RB in ZEA reduction was carried out in phosphate buffer and aqueous solution, respectively. Parameters of (Michaelis-Menten constant) (KM) and maximal rate (Vmax) were determined in the concentration range from 0.16 to 6 µg mL-1. ZEA reduction was determined and the mechanism of enzyme action was characterised by FTIR and high-pressure liquid chromatography-electrospray tandem mass spectrometry. Commercial POD and POD from RB and SB reduced ZEA concentration by 69.9%, 47.4% and 30.6% in 24 h, respectively. KM values were 39.61 and 8.90 µM, whereas Vmax values were 0.170 and 0.011 µM min-1 for commercial POD and POD from RB, respectively. The characterisation of the mechanism of enzyme action showed the oxidoreductive action of commercial POD in the mycotoxin. The use of commercial POD and POD from agro-industrial by-products, such as SB and RB, could be a promising alternative for ZEA biodegradation.

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.

The Binding Efficiency and Interaction of Lactobacillus casei Shirota Toward Aflatoxin B1

The use of probiotic as dietary approach to prevent exposure to food contaminant, aflatoxin B1 (AFB1) has greatly increased. Several studies found that AFB1 binding to the bacterial cell wall is strain-specific. Moreover, the interaction between AFB1 and bacterial cell wall is not well-understood, thus warrants further investigation. This research was conducted to assess the ability of Lactobacillus casei Shirota (Lcs) to bind AFB1 at different concentrations and to determine AFB1 binding efficiency of different Lcs cell components including live cell, heat-treated, and cell wall. In addition, the interaction between AFB1 and Lcs was also evaluated via scanning electron microscopy (SEM) and through an animal study. The binding of AFB1 by all Lcs cell components depends on the concentration of available AFB1. Among all Lcs cell components, the live Lcs cells exhibited the highest binding efficiency (98%) toward AFB1. Besides, the SEM micrographs showed that AFB1 induced structural changes on the bacterial cell surface and morphology including rough and irregular surface along with a curve rod-shaped. In vivo experiment revealed that Lcs is capable to neutralize the toxicity of AFB1 on body weight and intestine through the binding process. The animal’s growth was stunted due to AFB1 exposure, however, such effect was significantly (p < 0.05) alleviated by Lcs. This phenomenon can be explained by a significant (p < 0.05) decreased level of blood serum AFB1 by Lcs (49.6 ± 8.05 ng/mL) compared to AFB1-exposed rats without treatment (88.12 ± 10.65 ng/mL). Taken together, this study highlights the potential use of Lcs as a preventive agent against aflatoxicosis via its strong binding capability.

Adsorption of aflatoxin B1, zearalenone and ochratoxin A by microorganisms isolated from Kefir grains

A strategy to reduce the deleterious effects of mycotoxins is to use dietary supplements that contain microorganisms that bind mycotoxins and decrease their gastrointestinal absorption. Novel strains were isolated from a Kefir culture and assessed for their mycotoxin adsorption and biotransformation ability. The most active strains were identified using DNA sequencing, and the stability of microorganism/mycotoxin complexes was evaluated using buffer solutions to simulate the pH conditions in the gastrointestinal tract. Our results showed that the microorganism consortium of Kefir grains adsorbed 82 to 100% of aflatoxin B1 (AFB1), zearalenone (ZEA) and ochratoxin A (OTA) when cultivated in milk. The main strains that were capable of mycotoxin adsorption were identified as Lactobacillus kefiri, Kazachstania servazzii and Acetobacter syzygii. The strain L. kefiri KFLM3 was the most active, adsorbing 80 to 100% of the studied mycotoxins when cultivated in milk. Nonetheless, the strain K. servazzii KFGY7 retained more mycotoxin after the desorption experiments (65, 69 and 67% for AFB1, OTA and ZEA, respectively). These findings suggest that Kefir consumption may help to reduce gastrointestinal absorption of these mycotoxins and consequently reduce their toxic effects. The isolated strains may be of interest for the development of fermented dairy products for human consumption that have a new probiotic characteristic, the adsorption of mycotoxins.

Effects of Electron Beam Irradiation on Zearalenone and Ochratoxin A in Naturally Contaminated Corn and Corn Quality Parameters

Zearalenone (ZEN) and ochratoxin A (OTA) are secondary toxic metabolites widely present in grains and grain products. In this study, the effects of electron beam irradiation (EBI) on ZEN and OTA in corn and the quality of irradiated corn were investigated. Results indicated that EBI significantly affected ZEN and OTA. The degradation rates of ZEN and OTA at 10 kGy in solution were 65.6% and 75.2%, respectively. The initial amounts significantly affected the degradation rate. ZEN and OTA in corn were decreased by the irradiation dose, and their degradation rates at 50 kGy were 71.1% and 67.9%, respectively. ZEN and OTA were more easily degraded in corn kernel than in corn flour. Moisture content (MC) played a vital role in ZEN and OTA degradation. High MC was attributed to high ZEN and OTA degradation. The quality of irradiated corn was evaluated on the basis of irradiation dose. L* value changed, but this change was not significant (p > 0.05). By contrast, a* and b* decreased significantly (p < 0.05) with irradiation dose. The fatty acid value increased significantly. The pasting properties, including peak, trough, breakdown, and final and setback viscosities, were also reduced significantly (p < 0.05) by irradiation. Our study verified that EBI could effectively degrade ZEN and OTA in corn. Irradiation could also affect corn quality.

Detoxification of Aflatoxin B₁ by Zygosaccharomyces rouxii with Solid State Fermentation in Peanut Meal

Aflatoxins are highly carcinogenic, teratogenetic, and morbigenous secondary metabolites of Aspergillus flavus and A. parasiticus that can contaminate multiple staple foods, such as peanut, maize, and tree nuts. In this study, Zygosaccharomyces rouxii was screened out and identified from fermented soy paste—one kind of traditional Chinese food—to detoxify aflatoxin B₁ (AFB₁) by aerobic solid state fermentation in peanut meal. The optimal degradation condition was chosen from single factor experiment, and the most effective detoxification rate was about 97%. As for liquid fermentation, we tested the binding ability of Z. rouxii, and the highest binding rate reached was 74.3% (nonviable cells of Z. rouxii) in phosphate-buffered saline (PBS). Moreover, the biotransformation of AFB₁ through fermentation of Z. rouxii in peanut meal was further verified by liquid chromatography/mass spectrometry (LC/MS). According to TIC scan, after fermentation by Z. rouxii, the AFB₁ in peanut meal was prominently degraded to the lowering peaks of AFB₁. Additionally, m/s statistics demonstrated that AFB₁ may be degraded to some new products whose structural properties may be different from AFB₁, or the degradation products may be dissolved in the aqueous phase rather than the organic phase. As far as we know, this is the first report indicating that the safe strain of Z. rouxii has the ability to detoxify AFB₁.

Reaction of zearalenone and α-zearalenol with allyl isothiocyanate, characterization of reaction products, their bioaccessibility and bioavailability in vitro

This study investigates the reduction of zearalenone (ZEA) and α-zearalenol (α-ZOL) on a solution model using allyl isothiocyanate (AITC) and also determines the bioaccessibility and bioavailability of the reaction products isolated and identified by MS-LIT. Mycotoxin reductions were dose-dependent, and ZEA levels decreased more than α-ZOL, ranging from 0.2 to 96.9% and 0 to 89.5% respectively, with no difference (p⩽0.05) between pH 4 and 7. Overall, simulated gastric bioaccessibility was higher than duodenal bioaccessibility for both mycotoxins and mycotoxin-AITC conjugates, with duodenal fractions representing ⩾63.5% of the original concentration. Simulated bioavailability of reaction products (α-ZOL/ZEA-AITC) were lower than 42.13%, but significantly higher than the original mycotoxins. The cytotoxicity of α-ZOL and ZEA in Caco-2/TC7 cells was also evaluated, with toxic effects observed at higher levels than 75μM. Further studies should be performed to evaluate the toxicity and estrogenic effect of α-ZOL/ZEA-AITC.

Saccharomyces cerevisiae cell wall components as tools for ochratoxin a decontamination

The aim of this study was to evaluate the usefulness of Saccharomyces cerevisiae cell wall preparations in the adsorption of ochratoxin A (OTA). The study involved the use of a brewer’s yeast cell wall devoid of protein substances, glucans obtained by water and alkaline extraction, a glucan commercially available as a dietary supplement for animals and, additionally, dried brewer’s yeast for comparison. Fourier Transform Infrared (FTIR) analysis of the obtained preparations showed bands characteristic for glucans in the resulting spectra. The yeast cell wall preparation, water-extracted glucan and the commercial glucan bound the highest amount of ochratoxin A, above 55% of the initial concentration, and the alkaline-extracted glucan adsorbed the lowest amount of this toxin. It has been shown that adsorption is most effective at a close-to-neutral pH, while being considerably limited in alkaline conditions.