In vitro removal of ochratoxin A by two strains of Saccharomyces cerevisiae and their performances under fermentative and stressing conditions

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

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

Wine Microbiology and Predictive Microbiology: A Short Overview on Application, and Perspectives

Predictive microbiology (PM) is an essential element in food microbiology; its aims are the determination of the responses of a given microorganism combining mathematical models with experimental data under certain environmental conditions, and the simulation a priori of the growth/inactivation of a population based on the known traits of a food matrix. Today, a great variety of models exist to describe the behaviour of several pathogenic and spoilage microorganisms in foods. In winemaking, many mathematical models have been used for monitoring yeast growth in alcoholic fermentation as well as to predict the risk of contamination of grapes and grape products by mycotoxin producing fungi over the last years, but the potentialities of PM in wine microbiology are underestimated. Thus, the goals of this review are to show some applications and perspectives in the following fields: (1) kinetics of alcoholic and malolactic fermentation; (2) models and approaches for yeasts and bacteria growth/inactivation; (3) toxin production and removal.

Bacillus subtilis ANSB168 Producing d-alanyl-d-alanine Carboxypeptidase Could Alleviate the Immune Injury and Inflammation Induced by Ochratoxin A

Ochratoxin A (OTA) is toxic to animals and threatens food safety through residues in animal tissues. A novel degrading strain Bacillus subtilis ANSB168 was isolated and further investigated. We cloned d-alanyl-d-alanine carboxypeptidase DacA and DacB from ANSB168 and over-expressed them in Escherichia coli Rosetta (DE3). Then, we characterized the OTA degradation mechanism of DacA and DacB, which was degrading OTA into OTα. A total of 45 laying hens were divided into three equal groups. The control group was fed basal feed, and other groups were administered with OTA (250 μg/kg of feed). A freeze-dried culture powder of ANSB168 (3 × 10⁷ CFU/g, 2 kg/T of feed) was added to one of the OTA-fed groups for 28 days from day one of the experiment. We found that OTA significantly damaged the kidney and liver, inducing inflammation and activating the humoral immune system, causing oxidative stress in the layers. The ANSB168 bioproduct was able to alleviate OTA-induced kidney and liver damage, relieving OTA-induced inflammation and oxidative stress. Overall, DacA and DacB derived from ANSB168 degraded OTA into OTα, while the ANSB168 bioproduct was able to alleviate damages induced by OTA in laying hens.

Enhancement of β-Glucan Biological Activity Using a Modified Acid-Base Extraction Method from Saccharomyces cerevisiae

Beta glucan (β-glucan) has promising bioactive properties. Consequently, the use of β-glucan as a food additive is favored with the dual-purpose potential of increasing the fiber content of food products and enhancing their health properties. Our aim was to evaluate the biological activity of β-glucan (antimicrobial, antitoxic, immunostimulatory, and anticancer) extracted from Saccharomyces cerevisiae using a modified acid-base extraction method. The results demonstrated that a modified acid-base extraction method gives a higher biological efficacy of β-glucan than in the water extraction method. Using 0.5 mg dry weight of acid-base extracted β-glucan (AB extracted) not only succeeded in removing 100% of aflatoxins, but also had a promising antimicrobial activity against multidrug-resistant bacteria, fungi, and yeast, with minimum inhibitory concentrations (MIC) of 0.39 and 0.19 mg/mL in the case of resistant Staphylococcus aureus (MRSA) and Pseudomonas aeruginosa, respectively. In addition, AB extract exhibited a positive immunomodulatory effect, mediated through the high induction of TNFα, IL-6, IFN-γ, and IL-2. Moreover, AB extract showed a greater anticancer effect against A549, MDA-MB-232, and HepG-2 cells compared to WI-38 cells, at high concentrations. By studying the cell death mechanism using flow-cytometry, AB extract was shown to induce apoptotic cell death at higher concentrations, as in the case of MDA-MB-231 and HePG-2 cells. In conclusion, the use of a modified AB for β-glucan from Saccharomyces cerevisiae exerted a promising antimicrobial, immunomodulatory efficacy, and anti-cancer potential. Future research should focus on evaluating β-glucan in various biological systems and elucidating the underlying mechanism of action.

The impact of cultivation systems on the nutritional and phytochemical content, and microbiological contamination of highbush blueberry

The aim of this study was to compare the nutritional and use value of berries grown in organic and conventional systems. The polyphenol content, fruit colour and firmness, and yeast, mould, and mycotoxin contents were assessed in blueberry fruit freshly harvested and stored for 8 weeks in controlled conditions (CA: CO₂-12%; O₂-1.5%, temperature 1.5 °C). The Shannon–Wiener diversity index was comparable in both systems and was lower for mould in organic fruit than in conventional fruit. Mycotoxins (deoxynivalenol, zearalenone) were found only in organic fruits. The optimal mineral content and pH of the soil allowed the cultivation of blueberry in accordance with organic standards. The storage of highbush blueberry fruit in CA cold storage for 8 weeks resulted in a slight deterioration in fruit quality and polyphenol content. The lower nutritional value of these fruits is compensated by the lack of pesticides and artificial fertilizers residues. The use of fungicides in conventional cultivation reduces the population of sensitive fungi and therefore reduces the contamination of fruits with mycotoxins.

Degradation of ochratoxin A by supernatant and ochratoxinase of Aspergillus niger W-35 isolated from cereals

Ochratoxin A (OTA) is a mycotoxin produced by Aspergillus spp. and Penicillium spp. and poses a threat to food safety. Biodegradation may be a promising strategy for reducing the OTA contamination in the future. In this study, Aspergillus niger strain W-35 was isolated from cereals and studied for its ability to degrade OTA. Results showed that the supernatant of W-35 could degrade OTA both in vitro and in commercial feeds after incubation at 37 °C for 12 h by 78.0 and 37.0%, respectively. Ochratoxin α (OTα) was assayed as a degradation product by HPLC-FLD. Furthermore, an enzyme specific for OTA degradation (ochratoxinase, OTase) obtained from W-35 was successfully expressed in Escherichia coli BL21, and degraded OTA at a rate of 85.1% for 12 h. These results indicated that this OTA degradation is enzymatic and that the responsible enzyme is extracellular OTase. Reliable degradation of OTA has the potential for wide-ranging applications in the food and feed industries.

Occurrence and preventive strategies to control mycotoxins in cereal-based food

Mycotoxins contamination in cereal-based food is ubiquitous according to systematic review of the scientific documentation of worldwide mycotoxin contamination in cereal and their products between 2008 and 2018, thus representing food safety issue especially in developing tropical countries. Food processing plays a vital role to prevent mycotoxin contamination in food. Therefore, it is with great urgency to develop strategies to inhibit fungi growth and mycotoxin production during food processing. This review begins by discussing physicochemical properties of five most common mycotoxins (aflatoxins, fumonisins, ochratoxins, deoxynivalenol, and zearalenone) found in cereal grains, regulation for mycotoxins in food, and their potential negative impact on human health. The fate of mycotoxins during major cereal-based food processing including milling, breadmaking, extrusion, malting, and brewing was then summarized. In the end, traditional mitigation strategies including physical and chemical and potential application of biocontrol agent and essential oil nanoemulsions that can be applied during food processing were discussed. It indicated that no single method is currently available to completely prevent mycotoxin contamination in cereal foods.

Current methods for mycotoxins analysis and innovative strategies for their reduction in cereals: an overview

Mycotoxins are secondary metabolites produced by moulds in food that are considered a substantial issue in the context of food safety, due to their acute and chronic toxic effects on animals and humans. Therefore, new accurate methods for their identification and quantification are constantly developed in order to increase the performance of extraction, improve the accuracy of identification and reduce the limit of detection. At the same time, several industrial practices have shown the ability to reduce the level of mycotoxin contamination in food. In particular, a decrease in the amount of mycotoxins could result from standard processes naturally used for food processing or by procedures strategically introduced during processing, with the specific aim of reducing the amount of mycotoxins. In this review, the current methods adopted for accurate analyses of mycotoxins in cereals (aflatoxins, ochratoxins, trichothecenes, fumonisins) are discussed. In addition, both conventional and innovative strategies adopted to obtain safer finished products from common cereals intended for human consumption will be explored and analysed. © 2018 Society of Chemical Industry.

Advances in Biodetoxification of Ochratoxin A-A Review of the Past Five Decades

Ochratoxin A (OTA) is a toxic secondary fungal metabolite that widely takes place in various kinds of foodstuffs and feeds. Human beings and animals are inevitably threatened by OTA as a result. Therefore, it is necessary to adopt various measures to detoxify OTA-contaminated foods and feeds. Biological detoxification methods, with better safety, flavor, nutritional quality, organoleptic properties, availability, and cost-effectiveness, are more promising than physical and chemical detoxification methods. The state-of-the-art research advances of OTA biodetoxification by degradation, adsorption, or enzymes are reviewed in the present paper. Researchers have discovered a good deal of microorganisms that could degrade and/or adsorb OTA, including actinobacteria, bacteria, filamentous fungi, and yeast. The degradation of OTA to non-toxic or less toxic OTα via the hydrolysis of the amide bond is the most important OTA biodegradation mechanism. The most important influence factor of OTA adsorption capacity of microorganisms is cell wall components. A large number of microorganisms with good OTA degradation and/or adsorption ability, as well as some OTA degradation enzymes isolated or cloned from microorganisms and animal pancreas, have great application prospects in food and feed industries.

Impact of food processing and detoxification treatments on mycotoxin contamination

Mycotoxins are fungal metabolites commonly occurring in food, which pose a health risk to the consumer. Maximum levels for major mycotoxins allowed in food have been established worldwide. Good agricultural practices, plant disease management, and adequate storage conditions limit mycotoxin levels in the food chain yet do not eliminate mycotoxins completely. Food processing can further reduce mycotoxin levels by physical removal and decontamination by chemical or enzymatic transformation of mycotoxins into less toxic products. Physical removal of mycotoxins is very efficient: manual sorting of grains, nuts, and fruits by farmers as well as automatic sorting by the industry significantly lowers the mean mycotoxin content. Further processing such as milling, steeping, and extrusion can also reduce mycotoxin content. Mycotoxins can be detoxified chemically by reacting with food components and technical aids; these reactions are facilitated by high temperature and alkaline or acidic conditions. Detoxification of mycotoxins can also be achieved enzymatically. Some enzymes able to transform mycotoxins naturally occur in food commodities or are produced during fermentation but more efficient detoxification can be achieved by deliberate introduction of purified enzymes. We recommend integrating evaluation of processing technologies for their impact on mycotoxins into risk management. Processing steps proven to mitigate mycotoxin contamination should be used whenever necessary. Development of detoxification technologies for high-risk commodities should be a priority for research. While physical techniques currently offer the most efficient post-harvest reduction of mycotoxin content in food, biotechnology possesses the largest potential for future developments.

Metabolites of Microbial Origin with an Impact on Health: Ochratoxin A and Biogenic Amines

Safety and quality are significant challenges for food; namely, safety represents a big threat all over the world and is one of the most important goal to be achieved in both Western Society and Developing Countries. Wine safety mainly relies upon some metabolites and many of them are of microbial origin. The main goal of this review is a focus on two kinds of compounds (biogenic amines and mycotoxins, mainly Ochratoxin A) for their deleterious effects on health. For each class of compounds, we will focus on two different traits: (a) synthesis of the compounds in wine, with a brief description of the most important microorganisms and factors leading this phenomenon; (b) prevention and/or correction strategies and new trends. In addition, there is a focus on a recent predictive tool able to predict toxin contamination of grape, in order to perform some prevention approaches and achieve safe wine.

Differential Adsorption of Ochratoxin A and Anthocyanins by Inactivated Yeasts and Yeast Cell Walls during Simulation of Wine Aging

The adsorption of ochratoxin A (OTA) by yeasts is a promising approach for the decontamination of musts and wines, but some potential competitive or interactive phenomena between mycotoxin, yeast cells, and anthocyanins might modify the intensity of the phenomenon. The aim of this study was to examine OTA adsorption by two strains of Saccharomyces cerevisiae (the wild strain W13, and the commercial isolate BM45), previously inactivated by heat, and a yeast cell wall preparation. Experiments were conducted using Nero di Troia red wine contaminated with 2 μg/L OTA and supplemented with yeast biomass (20 g/L). The samples were analyzed periodically to assess mycotoxin concentration, chromatic characteristics, and total anthocyanins over 84 days of aging. Yeast cell walls revealed the highest OTA-adsorption in comparison to thermally-inactivated cells (50% vs. 43% toxin reduction), whilst no significant differences were found for the amount of adsorbed anthocyanins in OTA-contaminated and control wines. OTA and anthocyanins adsorption were not competitive phenomena. Unfortunately, the addition of yeast cells to wine could cause color loss; therefore, yeast selection should also focus on this trait to select the best strain.

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.

Selection of autochthonous Saccharomyces cerevisiae strains as wine starters using a polyphasic approach and ochratoxin A removal

Over the last few years, the selection of autochthonous strains of Saccharomyces cerevisiae as wine starters has been studied; however, researchers have not focused on the ability to remove ochratoxin A (OTA) as a possible trait to use in oenological characterization. In this article, a polyphasic approach, including yeast genotyping, evaluation of phenotypic traits, and fermentative performance in a model system (temperature, 25 and 30°C; sugar level, 200 and 250 g liter(-1)), was proposed as a suitable approach to select wine starters of S. cerevisiae from 30 autochthonous isolates from Uva di Troia cv., a red wine grape variety grown in the Apulian region (Southern Italy). The ability to remove OTA, a desirable trait to improve the safety of wine, was also assessed using enzyme-linked immunosorbent assay. The isolates, identified by PCR-restriction fragment length polymorphism analysis of the internal transcribed spacer region and DNA sequencing, were differentiated at strain level through the amplification of the interdelta region; 11 biotypes (I to XI) were identified and further studied. Four biotypes (II, III, V, VIII) were able to reduce OTA, with the rate of toxin removal from the medium (0.6 to 42.8%, wt/vol) dependent upon the strain and the temperature, and biotypes II and VIII were promising in terms of ethanol, glycerol, and volatile acidity production, as well as for their enzymatic and stress resistance characteristics. For the first time, the ability of S. cerevisiae to remove OTA during alcoholic fermentation was used as an additional trait in the yeast-selection program; the results could have application for evaluating the potential of autochthonous S. cerevisiae strains as starter cultures for the production of typical wines with improved quality and safety.