Aims:  To examine Saccharomyces cerevisae strains with previously reported beneficial properties and aflatoxin B1 binding capacity, for their ability to remove ochratoxin A (OTA) and zearalenone (ZEA) and to study the relation between cell wall thickness and detoxificant ability of yeast strains. Methods and Results:  A mycotoxin binding assay at different toxin concentrations and the effect of gastrointestinal conditions on mycotoxin binding were evaluated. Ultrastructural studies of yeast cells were carried out with transmission electronic microscopy. All tested strains were capable of removing OTA and ZEA. Saccharomyces cerevisiae RC012 and RC016 showed the highest OTA removal percentage, whereas RC009 and RC012 strains showed the highest ZEA removal percentages. The cell diameter/cell wall thickness relation showed a correlation between cell wall amount and mycotoxin removal ability. After exposure to gastrointestinal conditions, a significant increase in mycotoxin binding was observed. Conclusions:  All tested Saccharomyces cerevisiae strains were able to remove OTA and ZEA, and physical adsorption would be the main mechanism involved in ochratoxin A and ZEA removal. Gastrointestinal conditions would enhance adsorption and not decrease mycotoxin–adsorbent interactions. Significance and Impact of the Study:  Live strains with mycotoxin binding ability and beneficial properties are potential probiotics that could be included in animal feed. Previous and present results suggest that the RC008 and RC016 strains are very promising candidates for functional feed product development.

Mycotoxins are metabolites produced by fungi growing on foods or feeds and represent a serious hazard to humans and animals. Concerns related to the negative health impact of aflatoxins have led to the investigation of strategies to prevent, eliminate or reduce the presence of these toxins in contaminated products. Saccharomyces cerevisiae strains are among promising candidates that can be used in animal feed for improving the robustness of animals in the production environment. The aim of this work was to isolate and select S. cerevisiae strains from pig environment with aflatoxin B1 (AFB1) binding ability, able to tolerate gastrointestinal conditions and with some potential beneficial properties to the host. S. cerevisiae strains were isolated from animal feed, faeces and gut and identified by morphological and molecular techniques. AFB1 binding percentages varied among yeast strains according to the AFB1 concentration used. The RC016 strain showed the highest adsorption percentage at the three AFB1 concentrations tested in this work (50, 100 and 500 ng/ml) followed by RC008 strain. All yeast strains were able to survive under gastrointestinal conditions and to strongly adhere to Vero cells. All S. cerevisiae strains showed co-aggregation with pathogenic bacteria (Escherichia coli, Enterobacter cloacae and Salmonella enterica sub sp. enterica). Only RC016 and RC008 strongly inhibited the three pathogens assayed. S. cerevisiae strains RC016 and RC008 are promising microorganisms for inclusion in animal feed.

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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.

Aflatoxins (AF) are the most important mycotoxins produced by toxigenic strains of various Aspergillus spp. Biological decontamination of mycotoxins using microorganisms is a well-known strategy for the management of mycotoxins in feeds. Saccharomyces cerevisiae strains have been reported to bind aflatoxin B1 (AFB1). The aim of this study was to evaluate the ability of S. cerevisiae CECT 1891 in counteracting the deleterious effects of AFB1 in broiler chicks. Experimental aflatoxicosis was induced in 6-d-old broilers by feeding them 1.2 mg of AFB1/kg of feed for 3 wk, and the yeast strain was administrated in feed (10(10) cells/kg), in the drinking water (5 × 10(9) cells/L), or a combination of both treatments. A total of 160 chicks were randomly divided into 8 treatments (4 repetitions per treatment). Growth performance was measured weekly from d 7 to 28, and serum biochemical parameters, weights, and histopathological examination of livers were determined at d 28. The AFB1 significantly decreased the BW gain, feed intake, and impaired feed conversion rate. Moreover, AFB1 treatment decreased serum protein concentration and increased liver damage. The addition of S. cerevisiae strain to drinking water, to diets contaminated with AFB1, showed a positive protection effect on the relative weight of the liver, histopathology, and biochemical parameters. Furthermore, dietary addition of the yeast strain to drinking water alleviated the negative effects of AFB1 on growth performance parameters. In conclusion, this study suggests that in feed contaminated with AFB1, the use of S. cerevisiae is an alternative method to reduce the adverse effects of aflatoxicosis. Thus, apart from its excellent nutritional value, yeast can also be used as a mycotoxin adsorbent.

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Aims: To evaluate gliotoxin production by Aspergillus fumigatus strains isolated from feedstuff intended for domestic animals and pets, and to determine the amount of gliotoxin in these substrates. Methods and Results: A total of 150 feedstuff samples were collected. They were composed of 30 samples each of five different feed types (pigs, poultry, cattle, horse and pets). Aspergillus fumigatus gliotoxin production ability and gliotoxin presence in feedstuff was determined by HPLC. Aspergillus fumigatus strains were isolated from all of the tested samples. Strains from cattle, horses and pet food were able to produce gliotoxin. Corn silage samples intended for cattle did not show gliotoxin contamination. All the other tested samples had gliotoxin levels ranging from 29 to 209 lg g)1. Horse and poultry feed samples had the greatest contamination frequency. Conclusions: Feed samples contaminated with gliotoxin are potentially toxic to animals. Significance and Impact of the Study: The presence of gliotoxin could affect animal productivity and health. Moreover, there are risks of contamination to farm workers handling improperly stored animal feed. Aspergillus fumigatus strains isolated from different sources should be investigated to determine prevention and control strategies.This work was carried out with grants from PICT, SECYT (UNRC), Ministerio de Ciencia y Tecnologı´a de Co´ rdoba y PICT-CNPq

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