Effects of a mixed additive based on Saccharomyces cerevisiae and Lactobacillus rhamnosus on broilers exposed to aflatoxin B1 by contaminated feed

The objective of the present study was to explore the influence of dietary supplementation with a mixed additive (MA) containing a probiotic and anti-mycotoxin (Saccharomyces cerevisiae RC016 and Lactobacillus rhamnosus RC007) and its interaction on the performance and health (biochemistry and liver/intestine histopathology) of broilers fed diets contaminated with aflatoxin B1 (AFB1) at 506000±22.1ng/kg. The MA contained S. cerevisiae RC016 (1×107cells/g) and L. rhamnosus RC007 (1×108cells/g) in relation 1:1. A total of sixty-one-day-old Cobb broilers were randomly allocated into four treatment groups with three replicates of 5 birds each for a five-week-old feeding experiment. The experimental diet for each treatment (T) was formulated as follows: T1, a commercial diet (CD); T2, CD+AFB1; T3, CD+0.1% MA; T4, CD+AFB1+0.1% MA. The MA improved (p<0.01) production parameters (weight gain, conversion rate, and carcass yield) and reduced (p<0.01) the toxic effect of AFB1 on the relative weight of the livers. In addition, the macro and microscopic alterations of livers and the possible intestinal injury related to histological damage in the presence of mycotoxin were reduced. The use of probiotic MA based on S. cerevisiae RC016 and L. rhamnosus RC007 in animal feed provides greater protection against mycotoxin contamination and is safe for use as a supplement in animal feed, providing beneficial effects that improve animal health and productivity. This is of great importance at the economic level for the avian production system.

Potential benefits of yeast Saccharomyces and their derivatives in dogs and cats: a review

Yeast Saccharomyces and its derivatives have been largely used in livestock and poultry nutrition for their potential positive impact on growth, performance, and general health. Originally included in animal diets as a source of protein, yeasts can also offer a wide range of by-products with interesting bioactive compounds that would confer uses beyond nutrition. Although its supplementation in livestock, poultry and even in humans is well documented, the available body of literature on the use of yeast and its derivatives in companion animals' food, mainly dogs and cats' diets, is still developing. Despite this, gut microbiota modulation, immune system enhancement or decreasing of potentially pathogenic microorganisms have been reported in pets when using these products, highlighting their possible role as probiotics, prebiotics, and postbiotics. This review attempts to provide the reader with a comprehensive on the effects of Saccharomyces and its derivatives in pets and the possible mechanisms that confer their functional properties.

In-feed nutritional additive probiotic Saccharomyces boulardii RC009 can substitute for prophylactic antibiotics and improve the production and health of weaning pigs

Background and Aims

Non-therapeutic antibiotic use is associated with the current decrease in antibiotic therapeutic efficiency and the emergence of a wide range of resistant strains, which constitutes a public health risk. This study aimed to evaluate the use of Saccharomyces cerevisiae var. boulardii RC009 as a nutritional feed additive to substitute the prophylactic use of antibiotics and improve the productive performance and health of post-weaning piglets.

Materials and Methods

Four regular nutritional phases were prepared. Post-weaning pigs (21-70 days old) received one of two dietary treatments: T1-basal diet (BD-control group) with in-feed antibiotics as a prophylactic medication (one pulse of Tiamulin in P3 and one pulse of Amoxicillin in P4); and T2-BD without in-feed antibiotics but with Saccharomyces boulardii RC009 (1 × 1012 colony forming unit/T feed). The feed conversion ratio (FCR), total weight gain (TWG-kg), and daily weight gain (DWG-kg) were determined. A post-weaning growth index (GI) was calculated and animals (160 days old) from each treatment were analyzed at the abattoir after sacrifice for carcass weight and respiratory tract lesions.

Results

Pigs consuming probiotics had higher TWG and DWG than the control group. The group of animals with low body weight obtained the same results. Saccharomyces boulardii administration decreased diarrhea, and FCR reduction was related to a GI improvement. A significant increase in carcass weight and muscle thickness reduction was observed in animals received the probiotic post-weaning.

Conclusion

Saccharomyces boulardii RC009, a probiotic additive, was found to improve the production parameters of pigs post-weaning and enhance their health status, indicating that it may be a promising alternative to prophylactic antibiotics.

Mycotoxin Contamination Status of Cereals in China and Potential Microbial Decontamination Methods

The presence of mycotoxins in cereals can pose a significant health risk to animals and humans. China is one of the countries that is facing cereal contamination by mycotoxins. Treating mycotoxin-contaminated cereals with established physical and chemical methods can lead to negative effects, such as the loss of nutrients, chemical residues, and high energy consumption. Therefore, microbial detoxification techniques are being considered for reducing and treating mycotoxins in cereals. This paper reviews the contamination of aflatoxins, zearalenone, deoxynivalenol, fumonisins, and ochratoxin A in major cereals (rice, wheat, and maize). Our discussion is based on 8700 samples from 30 provincial areas in China between 2005 and 2021. Previous research suggests that the temperature and humidity in the highly contaminated Chinese cereal-growing regions match the growth conditions of potential antagonists. Therefore, this review takes biological detoxification as the starting point and summarizes the methods of microbial detoxification, microbial active substance detoxification, and other microbial inhibition methods for treating contaminated cereals. Furthermore, their respective mechanisms are systematically analyzed, and a series of strategies for combining the above methods with the treatment of contaminated cereals in China are proposed. It is hoped that this review will provide a reference for subsequent solutions to cereal contamination problems and for the development of safer and more efficient methods of biological detoxification.

Respiratory tract clinometry, fat thickness, haematology and productive parameters associated with direct-fed microbials used as growth promoter antibiotic alternative in weaned piglets

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Both probiotics reduced lumbar fat thickness.

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The probiotics inclusion showed a tendency to increase the carcass weight.

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Direct-fed microbials demonstrated their ability to substitute as antibiotics usage.

The objective was to evaluate the effect of two probiotic yeast strains (Saccharomyces. cerevisiae RC016 and Kluyveromyces marxianus VM004) as a substitute of growth promoter antibiotics on health status and productive parameters in weaned piglets. Commercial line hybrid piglets (Choice n=200), weaned at 21 d age were allotted by sex, and assigned in 4 pens per treatment (2 pens males and 2 pens females), 10 pigs per pen divided into 2 blocks (with or without antibiotics). Dietary treatments included a basal diet (BD) supplemented with probiotic Saccharomyces cerevisiae RC016 and Kluyveromyces marxianus VM004 (100 g, 1 × 1010 CFU/g, respectively), with or without antibiotics, mixed per ton of growth phases diets. Pigs were fed ad libitum with treatments T1) BD with antibiotics (BD); T2) BD with antibiotics + Saccharomyces cerevisiae; T3) BD without antibiotics + Saccharomyces cerevisiae; T4) BD with antibiotics + Kluyveromyces marxianus; T5) BD without antibiotics + Kluyveromyces marxianus. The effects on respiratory tract clinometry, carcass quality, organs weight, blood haematology and productive parameters were evaluated. When clinical signs occurred (diarrhoea, stomach ulcers, respiratory signs), they decreased with both probiotics addition, mainly Saccharomyces cerevisiae. The productive parameters promotion by both probiotics was similar than that using antibiotics. The probiotics inclusion increased the carcass weight and significantly reduced the lumbar fat thickness (P ≤ 0.05). Supplementation with both probiotics demonstrated their ability to substitute the antibiotics use on clinometry, carcass quality and on the productive parameters promotion of weaned piglets.

Probiotic gut-borne Saccharomyces cerevisiae reduces liver toxicity caused by aflatoxins in weanling piglets

The present study was conducted to investigate the aflatoxin B1 (AFB1) liver toxicity and gut histomorphometry after gut borne-Saccharomyces cerevisiae supplementation to AFB1-contaminated piglet diets. Thirty-two male mixed-breed piglets (weaned at 21 days old) were housed in individual pens and allowed to acclimate for 7 days. Animals were randomly assigned to four treatments of 22 days: T1 – low AFB1 levels diet (L, 31.6 μg/kg); T2 – L + S. cerevisiae 1 g/kg; T3 – high AFs levels diet (H, 495 μg/kg); T4 – H + S. cerevisiae 1 g/kg. The addition of probiotic yeast was able to reduce 72% of residual AFB1 present in the liver. The liver histopathology of piglets fed AFB1 showed a typical macroscopic and microscopic pattern of subclinical aflatoxicosis that was prevented by the yeast. Also, the addition of the yeast was able to decrease the alanine-aminotransferase (25.5±0.71 U) and aspartate-aminotransferase (26.5±6.10 U) even showing values lower than the control ones. The apparent absorption area showed the greater surface when the probiotic was present alone compared to the control (T1), whereas when present together with the toxin demonstrated a modulatory effect. The addition of probiotic gut-borne S. cerevisiae in the pig diets was effective in counteracting the toxic effects of harmful AFB1 in livers besides a tendency to improve the histomorphometric parameters and modulating the toxic effect of AFB1 on intestine. These results are promising for the production of feed additives that will be used in animal feed, since the probiotic action and the decontamination of mycotoxins in the same product are complemented.

Effect of Saccharomyces cerevisiae addition to feed contaminated with aflatoxin B1 on the health and performance indices of tambaqui (Colossoma macropomum) fingerlings

The objective of this study was to evaluate the effects of the addition of Saccharomyces cerevisiae to feed contaminated with aflatoxin B1 (AFB1) on the performance and health of tambaqui fingerlings. A fully randomised study design was used, represented by four treatments: (T1) with 0.0 μg/kg of AFB1 and 0.0 colony forming unit (cfu)/g of yeast (control); (T2) with 0.0 μg/kg of AFB1 and 106 cfu/g of yeast; (T3) with 100 μg/kg of AFB1 and 0.0 cfu/g of yeast and (T4) with 100 μg/kg of AFB1 and 106 cfu/g of yeast, with four repetitions per treatment. Over a period of 34 days, 192 fingerlings with an initial weight of 2.9±0.2 g and length of 26.1±1.3 mm were used, distributed in 16 tanks with 12 fish per experimental unit. The following parameters were evaluated: water quality, zootechnical performance, histopathological analysis, counting and isolation of yeasts from the feed and intestine. No significant differences were observed (P>0.05) in the initial weight, initial length, final length, specific growth rate, mean length gain, Fulton condition factor (K Factor) or survival rate of the tambaqui fingerlings during the trial period. Statistical differences (P<0.05) were found between the treatments with respect to fingerling final weight, mean weight gain and average feed intake. Histopathological changes in the liver and kidney tissues from tambaqui fingerlings were more pronounced in T3 and T4. Based on histopathological findings, the yeast was unable to reduce the characteristic effects of aflatoxicosis in tambaqui fingerlings fed with 100 μg/kg AFB1. The S. cerevisiae A8L2 strain was able to colonise the intestine of tambaqui fingerlings, however, its addition in conjunction with 100 μg/kg AFB1 to fingerling feed did not promote improvements in performance indices or the histopathological parameters of these animals.

Probiotics as a biological detoxification tool of food chemical contamination: A review

Nowadays, people are exposed to diverse environmental and chemical pollutants produced by industry and agriculture. Food contaminations such as persistent organic pollutants (POPs), heavy metals, and mycotoxins are a serious concern for global food safety with economic and public health implications especially in the newly industrialized countries (NIC). Mounting evidence indicates that chronic exposure to food contaminants referred to as xenobiotics exert a negative effect on human health such as inflammation, oxidative stress, and intestinal disorders linked with perturbation of the composition and metabolic profile of the gut microflora. Although the physicochemical technologies for food decontamination are utilized in many cases but require adequate conditions which are often not feasible to be met in many industrial sectors. At present, one promising approach to reduce the risk related to the presence of xenobiotics in foodstuffs is a biological detoxification done by probiotic strains and their enzymes. Many studies confirmed that probiotics are an effective, feasible, and inexpensive tool for preventing xenobiotic-induced dysbiosis and alleviating their toxicity. This review aims to summarize the current knowledge of the direct mechanisms by which probiotics can influence the detoxification of xenobiotics. Moreover, probiotic-xenobiotic interactions with the gut microbiota and the host response were also discussed.

Influence of technological procedures on viability, probiotic and anti-mycotoxin properties of Saccharomyces boulardii RC009, and biological safety studies

The objective was to evaluate the technological processing (protection strategies and storage conditions) influence on viability, on probiotic properties and adsorbent aflatoxin B₁ capacity of S. boulardii RC009. Also, the yeast biological safety was evaluated. Lyophilisation (DL) and encapsulation ​+ ​lyophilisation (EL) were conducted. Yeast protected with maltodextrin (M) or WPC stored at 4 ​°C reduced 1 and 2 log the viability, respectively. Yeast protected with M stored at 25 ​°C reduced 1 log after 70 ​d; with WPC the viability significantly reduced 3 log after 30 ​d. Technological processing improved the coaggregation’s capacity with pathogens and DL process allowed the greatest AFB₁ adsorption. S. boulardii 10⁶ ​cells/mL were no toxic to Vero cells (p˂0.05). Saccharomyces boulardii RC009 protected with M or WPC maintained viability after technological processing. It possesses a great capacity for AFB₁ adsorption and probiotic properties and could be considered a candidate with proven safety for functional food products development.

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Commercial refinery syrup was a good substrate for Saccharomyces boulardii growth.

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Maltodextrin and WPC were efficient protectors in ensuring the yeast viability.

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The lyophilised yeast achieved high percentages of AFB1 adsorption.

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Saccharomyces boulardii cells were non-toxic in Vero cells up to 106 ​CFU/mL.

Biological Control and Mitigation of Aflatoxin Contamination in Commodities

Aflatoxins (AFs) are toxic secondary metabolites produced mostly by Aspergillus species. AF contamination entering the feed and food chain has been a crucial long-term issue for veterinarians, medicals, agroindustry experts, and researchers working in this field. Although different (physical, chemical, and biological) technologies have been developed, tested, and employed to mitigate the detrimental effects of mycotoxins, including AFs, universal methods are still not available to reduce AF levels in feed and food in the last decades. Possible biological control by bacteria, yeasts, and fungi, their excretes, the role of the ruminal degradation, pre-harvest biocontrol by competitive exclusion or biofungicides, and post-harvest technologies and practices based on biological agents currently used to alleviate the toxic effects of AFs are collected in this review. Pre-harvest biocontrol technologies can give us the greatest opportunity to reduce AF production on the spot. Together with post-harvest applications of bacteria or fungal cultures, these technologies can help us strictly reduce AF contamination without synthetic chemicals.

Saccharomyces cerevisiae as a probiotic agent and a possible aflatoxin B1 adsorbent in simulated fish intestinal tract conditions

ABSTRACT The aim of this study was to evaluate in vitro the probiotic potential and absorption of Saccharomyces cerevisiae for the aflatoxin B1 in simulated fish intestinal tract conditions. Three yeast strains were used, two from brewery: S. cerevisiae RC1 and S. cerevisiae RC3 and one from a fish farming environment: S. cerevisiae A8L2. The selected yeasts were subjected to the following in vitro tests: homologous inhibition, self-aggregation, co-aggregation, antibacterial activity, gastrointestinal conditions tolerance and adsorption of AFB1. All S. cerevisiae strains showed good capability of self-aggregation and co-aggregation with pathogenic bacteria. All yeast strains were able to survive the gastrointestinal conditions. In acidic conditions, the factors (strain vs. time) had interaction (P=0.0317), resulting in significant variation among the strains tested in the time periods analyzed. It was observed that there was also interaction (P=0.0062) in intestinal conditions, with an increased number of cells in the 12-hour period for all strains tested. In the adsorption test, the A8L2 strain was statistically more effective (P<0.005) for both AFB1 concentrations evaluated in this study (10 and 25ng/mL). Thus, it was observed that the strains of S. cerevisiae have potential probiotic and adsorbent of AFB1.

Aflatoxin B1 adsorption/desorption dynamics in the presence of Lactobacillus rhamnosus RC007 in a gastrointestinal tract-simulated model

AIMS

(i) To determine the aflatoxin B₁ (AFB₁ ) adsorption and desorption dynamics in the presence of Lactobacillus rhamnosus RC007 under simulated transit of AFB₁ at each gastrointestinal tract (GIT-saliva, stomach and intestine) stage consecutively and then, separately, (ii) to study the ability of L. rhamnosus RC007 to biotransform AFB₁ as a strategy that complements the adsorption process.

METHODS AND RESULTS

The AFB₁ adsorption and desorption assay simulating the GIT passage of AFB₁ (93·89 ng g^-1 ) in the presence of L. rhamnosus RC007 (10⁸ CFU per ml) was conducted. Moreover, lactic acid production was determined. Results demonstrated that predominant environmental conditions in salivary solution induced a low AFB₁ adsorption, while the transit through the gastric solution and intestinal solution allowed high percentages of adsorption and did not generate significant AFB₁ desorption.

CONCLUSIONS

The AFB₁ adsorption and desorption dynamics in the presence of L. rhamnosus RC007 was favoured by gastric and intestinal environment.

SIGNIFICANCE AND IMPACT OF THE STUDY

The knowledge of the adsorption dynamics of AFB₁ with a micro-organism of interest will allow predicting its behaviour at each stage of the GIT.

Beneficial effects of Saccharomyces cerevisiae RC016 in weaned piglets: in vivo and ex vivo analysis

Probiotics represents an alternative to replace antibiotics as growth promoters in animal feed and are able to control enteric bacterial diseases and to improve gut immunity. Saccharomyces cerevisiae RC016 showed previously inhibition/coagregation of pathogens) and mycotoxins adsorbent ability (aflatoxin B₁, ochratoxin A and zearalenone). The aim of this work was to evaluate beneficial properties of S. cerevisiae RC016 in a non-inflammatory in vivo model in weaned piglets and in an intestinal inflammation ex vivo model induced by the mycotoxin deoxynivalenol (DON). Secretory immunoglobulin A (s-IgA) levels, intestinal cytokines, goblet cells and production parameters were evaluated in a pig model. For the in vivo assays, twelve pigs were weaned at 21 days and assigned to two groups: Control (n=6) and Yeast (n=6). Animals received yeast strain for three weeks. After 22 days the small intestine was recovered for determination of goblet cells and s-IgA. For the ex vivo assay, jejunal explants were obtained from 5 weeks old crossbred piglets and treated as follow: (1) control; (2) treated for 3 h with 10 μM DON used as an inflammatory stressor; (3) incubated with 10⁷ cfu/ml yeast strain; (4) pre-incubated 1 h with 10⁷ cfu/ml yeast strain and then treated for 3 h with 10 μM DON. CCL20, interleukin (IL)-1β, IL-8 and IL-22 gene expression was determined by qPCR. Oral administration of S. cerevisiae RC016 increased s-IgA, the number of goblet cells in small intestine and all the growth parameters measured. In the ex vivo model, the cytokine profile studied showed a potential anti-inflammatory effect of the administration of the yeast. In conclusion, S. cerevisiae RC016 is a promising candidate for feed additives formulation to improve animal growth and gut immune system. This yeast strain could be able to improve the gut health through counteracting the weaning-associated intestinal inflammation in piglets.

The production of yeast cell wall using an agroindustrial waste influences the wall thickness and is implicated on the aflatoxin B1 adsorption process

The objectives of this study were: to evaluate the use of dry distillery grain soluble extract - DDGse to produce yeast biomass and to obtain cell wall (CW), to use the CW as an aflatoxin B₁ (AFB₁) adsorbent, to study the variation in the composition and thickness of the CW under the influence of DDGse to evaluate their implication on the adsorption process using transmission electron microscopy (TEM) and fourier-transform infrared spectroscopy (FITR). The production of biomass and CW were variable. The CW thickness values showed that S. boulardii strain grown in yeast extract peptone dextrose (YPD) or DDGse medium, with no significant differences observed. The thickness of the CW for S. cerevisiae (RC012 and VM014) were increased when the cells were grown in DDGse medium, the thickness was almost double compared to the values obtained in YPD medium. The spectra IR of each CW in the two culture media shown regions corresponding to polysaccharides, proteins and lipids. Cells grown in DDGse medium adsorbed more AFB₁ than those grown in YPD. The CW adsorbed more AFB₁ than the same amount of whole cell. Future studies should be done to determine the type of carbohydrates and the relationship between chitin - beta glucans responsible for mycotoxin adsorption.

Pediococcus acidolactici and Pediococcus pentosaceus isolated from a rainbow trout ecosystem have probiotic and ABF1 adsorbing/degrading abilities in vitro

Probiotics are being used in biological control of bacterial pathogens, as an alternative to antibiotics, to improve health and production parameters in fish farming. Fish farming production is severely affected by aflatoxins (AFs), which are a significant problem in aquaculture systems. Aflatoxins exert substantial impact on production, causing disease with high mortality and a gradual decline of reared fish stock quality. Some aspects of aflatoxicosis in fish, particularly its effects on the gastrointestinal tract, have not been well documented. The aim of the present study was to evaluate probiotic properties of lactic acid bacterial (LAB) strains isolated from rainbow trout intestine and feed. Moreover, AFB₁-binding and/or degrading abilities were also evaluated to assess their use in the formulation of feed additives. Growth at pH 2, the ability to co-aggregate with bacterial pathogens, inhibition of bacterial pathogens, and determination of the inhibitory mechanism were tested. Aflatoxin B₁ (AFB₁) adsorption and degradation ability were also tested. All strains were able to maintain viable (10⁷ cells ml^-1) at pH 2. Pediococcus acidilactici RC001 and RC008 showed the strongest antimicrobial activity, inhibiting all the pathogens tested. The strains produced antimicrobial compounds of different nature, being affected by different treatments (catalase, NaOH and heating), which indicated that they could be H₂O_2, organic acids or proteins. All LAB strains tested showed the ability to coaggregate pathogenic bacteria, showing inhibition percentages above 40%. Pediococcus acidilactici RC003 was the one with the highest adsorption capacity and all LAB strains were able to degrade AFB₁ with percentages higher than 15%, showing significant differences with respect to the control. The ability of some of the LAB strains isolated in the present work to compete with pathogens, together with stability against bile and gastric pH, reduction of bioavailability and degradation of AFB₁, may indicate the potential of LAB for use in rainbow trout culture.

Evaluation of Saccharomyces cerevisiae as an anti-fumonisin B1 additive in a horse digestion model

In this study, the capacity of Saccharomyces cerevisiae to adsorb fumonisin B1 (FB1) was evaluated in in vitro assays. The digestion of nutrients from maize contaminated with FB1 was assessed as well as the influence of digestive enzymes and pH on the bioavailability of FB1 in solution. Adsorption assays in buffers containing 5 µg/ml of FB1 were conducted to determine the strain to be used in the in vitro digestion assays. Four different yeast strains (1, 2, 3 and 4) along with five different cell concentrations of each one were studied under pH 2 and 6.8 at 39 °C. Strain 4 showed higher adsorption values at 1×109 cfu/ml, adsorbing 39.4% of the mycotoxin at pH 2 and 37.5% at pH 6.8. After that, the in vitro enzymatic digestion was conducted in two separated experiments. First, maize artificially contaminated with FB1 (5 µg/g) was used in five different treatments. Then, assays with maize naturally contaminated with FB1 (Maize A: 3.2 µg/g and Maize B: 29.0 µg/g) were conducted. In all samples, FB1 was quantified by HPLC-FL in liquid fraction and in solid residue. Samples of maize in natura and solid residues were subjected to chemical analysis of dry matter, organic matter, crude protein, neutral detergent fibre and starch to estimate the digestion of nutrients. The presences of FB1 and S. cerevisiae (Strain 4) in these assays had no influence on the digestion of the maize nutrients. The adsorption capacity of yeast was observed more clearly in treatments with higher concentrations of FB1 in the maize grain. S. cerevisiae strain 4 removed between 8 to 18% of FB1 in solution, showing a limited capacity to adsorb FB1 under in vitro conditions of horse enzymatic digestion.

Aflatoxins and Saccharomyces cerevisiae: yeast modulates the intestinal effect of aflatoxins, while aflatoxin B1 influences yeast ultrastructure

The gastrointestinal tract (GIT) is the main site where absorption of food components takes place and the first system coming into contact with mycotoxins of dietary origin. The aim of this work was to study the effect of probiotic Saccharomyces cerevisiae RC016 on intestinal villi of rats exposed to aflatoxins for 60 days. Moreover, the effect of in vitro aflatoxin B1 (AFB1) exposure on yeast cell ultrastructure was evaluated. Six treatments were applied (n=6) to inbred male Wistar rats: (1) uncontaminated feed control (F); (2) yeast control; (3) F + 40 μg/kg AFB1 + 20 μg/kg aflatoxin G1 (AFG1); (4) F + 100 μg/kg AFB1 + 50 μg/kg AFG1; (5) F + 40 μg/kg AFB1 + 20 μg/kg AFG1 + daily oral dose 108 viable S. cerevisiae cells; and (6) F + 100 μg/kg AFB1 + 50 μg/kg AFG1 + daily oral dose 108 viable S. cerevisiae cells. Morphometric measurements (villus length and width, crypt depth, quantification of goblet cells) were assessed using image analysis. S. cerevisiae RC016 cells were exposed to 20 μg/ml of AFB1 in intestinal solutions or in phosphate buffered saline and cells processed for transmission electron microscopy and high resolution light microscopy studies. Dietary exposure to the yeast did not induce significant differences in villus width but increased villus length and crypt depth. Aflatoxin-contaminated diets induced an increase in villus length, width and crypt depth and a significant decrease in the number of goblet cells which were improved by the addition of S. cerevisiae RC016. A significant increase in the yeast cell diameter was observed when RC016 was exposed to aflatoxins, suggesting this as an advantage since a larger cell would be able to adsorb mycotoxins more efficiently. The ability of this strain to act as probiotic and aflatoxin binder makes it a candidate for the formulation of new additives to improve animal performance.

Bakery by-products based feeds borne-Saccharomyces cerevisiae strains with probiotic and antimycotoxin effects plus antibiotic resistance properties for use in animal production

The aim of this study was to select S. cerevisiae strains able to exert probiotic and antimycotoxin effects plus antibiotics resistance properties for use in animal production. S. cerevisiae LL74 and S. cerevisiae LL83 were isolated from bakery by-products intended for use in animal feed and examined for phenotypic characteristics and nutritional profile. Resistance to antibiotic, tolerance to gastrointestinal conditions, autoaggregation and coaggregation assay, antagonism to animal pathogens and aflatoxin B₁ binding were studied. S. cerevisiae LL74 and S. cerevisiae LL83 showed resistance to all the antibiotics assayed (ampicillin, streptomycin, neomycin, norfloxacin, penicillin G, sulfonamide and trimethoprim). The analysis showed that exposure time to acid pH had a significant impact onto the viable cell counts onto both yeast strains. Presence of bile 0.5% increased significantly the growth of the both yeast strains. Moreover, they were able to tolerate the simulated gastrointestinal conditions assayed. In general, the coaggregation was positive whereas the autoaggregation capacity was not observed. Both strains were able to adsorb AFB₁. In conclusion, selected S. cerevisiae LL74 and S. cerevisiae LL83 have potential application to be used as a biological method in animal feed as antibiotic therapy replacement in, reducing the adverse effects of AFB₁ and giving probiotic properties.

Development of an in vitro method for the prediction of mycotoxin binding on yeast-based products: case of aflatoxin B₁, zearalenone and ochratoxin A

To date, no official method is available to accurately define the binding capacity of binders. The goal is to define general in vitro parameters (equilibrium time, pH, mycotoxin/binder ratio) for the determination of binding efficacy, which can be used to calculate the relevant equilibrium adsorption constants. For this purpose, aflatoxin B1 (AFB1), zearalenone (ZEA) or ochratoxin A (OTA) were incubated with one yeast cell wall in pH 3, pH 5 or pH 7 buffers. The percentage of adsorption was recorded by quantitation of remaining mycotoxins in the supernatant and amount of mycotoxin adsorbed on the residue. The incubation of yeast cell wall in the presence of mycotoxins solved in buffer, lead to unexpected high adsorption percentage when the analysis was based only on remaining mycotoxins in the supernatant. The decrease of mycotoxins in the supernatant was not correlated to the amount of mycotoxins found in the residue. For this reason we modified the conditions of incubation. Yeast cell wall (5 mg) was pre-incubated in buffer (990 μl) at 37 °C during 5 min and then 10 μl of an alcoholic solution of mycotoxin (concentration 100 times higher than the final concentration required in the test tube) were added. After incubation, the solution was centrifuged, and the amount of mycotoxins were analysed both in the supernatant and in the residue. A plateau of binding was reached after 15 min of incubation whatever the mycotoxins and the concentrations tested. The adsorption of ZEA was better at pH 5 (75 %), versus 60 % at pH 3 and 7. OTA was only significantly adsorbed at pH 3 (50 %). Depending on the pH, the adsorptions of OTA or ZEA were increased or decreased when they were together, indicative of a cooperative effect.

In vitro study on the effect of Saccharomyces cerevisiae strains on growth and mycotoxin production by Aspergillus carbonarius and Fusarium graminearum

The effect of Saccharomyces cerevisiae RC008 and RC016 strains, previously selected based on their aflatoxin B₁ mycotoxin binding ability and beneficial properties, against Aspergillus carbonarius and Fusarium graminearum under different interacting environmental conditions was evaluated. In vitro studies on the lag phase, growth rate and ochratoxin A/zearalenone and DON production were carried out under different regimens of a(w) (0.95 and 0.99); pH (4 and 6); temperature (25 and 37 °C) and oxygen availability (normal and reduced). Both yeast strains showed antagonistic activity and decreasing growth rate compared to the control. In general, the RC016 strain showed the greatest inhibitory activity. Except at the interacting condition 0.95 a(W), normal oxygen availability and 37 °C, at both pH values, A. carbonarius and F. graminearum were able to produce large amounts of mycotoxins in vitro. In general, a significant decrease in levels of mycotoxins in comparison with the control was observed. S. cerevisiae RC008 and RC016 could be considered as effective agents to reduce growth and OTA, ZEA and DON production at different interacting environmental conditions, related to those found in stored feedstuff. The beneficial and biocontrol properties of these strains are important in their use as novel additives for the control of mycotoxigenic fungi in stored feedstuffs.

Saccharomyces cerevisiae strains and the reduction of Aspergillus parasiticus growth and aflatoxin B1 production at different interacting environmental conditions, in vitro

The effect of Saccharomyces cerevisiae RC008 and RC016, previously selected based on their aflatoxin B(1) binding ability and beneficial properties, against Aspergillus parasiticus under different interacting environmental conditions was evaluated. Studies concerning the lag phase, growth rate and aflatoxin B(1) production were carried out in vitro under different regimes of a (w) (0.95 and 0.99), pH (4 and 6), temperature (25 and 37°C), and oxygen availability (normal and reduced). Both yeast strains showed great antagonistic activity at pH 4, decreasing growth rate compared with the control. The RC008 strain showed the greatest inhibitory activity at all assayed conditions. A. parasiticus produced large amounts of AFB(1) in vitro. A significant decrease of AFB(1) levels in comparison with the control were observed with yeast interaction. Differences between control and treatment values ranged from 130 to 5400 ng ml(-1). S. cerevisiae RC008 and RC016 could be considered as effective agents in reducing growth and AFB(1) production at different interacting environmental conditions, related to that found in stored feedstuff. The importance of the present work lies in the search for live strains with both probiotic and biocontrol properties able to prolong the safe storage of feedstuff and exert beneficial properties after animal consumption and which could be included in a novel product for animal feed.

Evaluation of Saccharomyces cerevisiae strains as probiotic agent with aflatoxin B₁ adsorption ability for use in poultry feedstuffs

In this study the aflatoxin B₁ (AFB₁) removal capacity, the tolerance to salivary and gastrointestinal conditions, autoaggregation and coaggregation with pathogenic bacteria of Saccharomyces cerevisiae strains isolated from broiler feces, were evaluated. Only four of twelve isolated strains were identified as Saccharomyces cerevisiae using molecular techniques. The results obtained in AFB₁ binding studies indicated that the amount of AFB₁ removed was both strain and mycotoxin-concentration dependent. Therefore, a theoretical model was applied in order to select the most efficient strain to remove AFB₁ in a wide range of mycotoxin concentration. The results indicated that S. cerevisiae 08 and S. cerevisiae 01 strains were the most efficient microorganisms in the mycotoxin removal. Viability on simulated salivary and gastrointestinal conditions was investigated and S. cerevisiae 08 strain showed the best results, achieving 98% of total survival whereas S. cerevisiae 01 reached only 75%. Autoaggregation and coaggregation assays showed S. cerevisiae 08 as the most appropriate strain, mainly because it was the unique strain able to coaggregate with the four bacterial pathogens assayed. Consequently, S. cerevisiae 08 is the best candidate for future in vivo studies useful to prevent aflatoxicosis. Further quantitative in vitro and in vivo studies are required to evaluate the real impact of yeast-binding activity on the bioavailability of AFB₁ in poultry. However, this study could be useful in selecting efficient strains in terms of AFB₁ binding and provide an important contribution to research into microorganisms with potential probiotic effects on the host.

Saccharomyces cerevisiae strains retain their viability and aflatoxin B1 binding ability under gastrointestinal conditions and improve ruminal fermentation

The aim was to evaluate both the ability of yeast strains to survive and bind AFB(1) under ruminant gastrointestinal conditions and the effect of these yeast strains on ruminal fermentation. Yeast viability was studied under simulated gastrointestinal conditions. AFB(1) binding ability was evaluated at different pH values as present in the ruminant gastrointestinal tract. The effect of yeast strains on cellulose digestion and volatile fatty acids production by ruminal bacteria was also evaluated. All yeast strains were able to survive under gastrointestinal conditions and to adsorb AFB(1) at the different pH assayed. The strain RC016 showed the highest binding percentage at the three tested pH. The number of cellulolytic bacteria in ruminal fluid increased in the presence of RC008 and RC016 yeast strains. The concentration of acetate and propionate after ruminal fermentation increased with the addition of RC008 and RC016 strains; this effect was less significant with RC009 strain. Strains RC008 and RC016 are potential probiotic to be included in animal feed: they help to increase fibber digestibility and could reduce AFB(1 )bioavailability in the gastrointestinal tract. Viable S. cerevisiae RC008 and RC016 strains with both probiotic and mycotoxins adsorption properties could be used as feed additives in ruminant feedstuff.