The aim of the present study was to determine species of the fungal genera Aspergillus, Fusarium, and Penicillium and fumonisin B₁ (FB₁), aflatoxin B₁ (AFB₁), and ochratoxin A (OTA) contamination from feed intended for fish farms. A total of 60 samples were sampled from tilapia farms in the Rio de Janeiro State, Brazil. The quantitative enumeration of fungi as colony-forming units per gram of feed (CFU/g) was performed using the surface spread method in different culture media. The results were expressed as fungal isolation frequency and relative density. Fungal total counts ranged from <1 × 10² to 4.7 × 10⁴ CFU/g. Fusarium counts were not observed. Among toxigenic genera, Aspergillus (68%) was the most prevalent, followed by Penicillium species (60%). Aspergillus niger aggregate (36%), Aspergillus flavus (35%), and Penicillium citrinum (71%) were the most prevalent species. A high percentage of samples (98%) were contaminated with FB₁ levels, while 55% and 3.3% were contaminated with AFB₁ and OTA, respectively. The simultaneous occurrence of these mycotoxins emphasizes the need for further research in the area to better assess the risk to the health of fish farms and their implications for the health of consumers of this meat.

Zearalenone (ZEA) and its derivatives are mycotoxins with estrogenic effects on mammals. The biotransformation for ZEA in animals involves the formation of two major metabolites, α- and β-zearalenol (α-ZOL and β-ZOL), which are subsequently conjugated with glucuronic acid. The capability of Saccharomyces cerevisiae strains isolated from silage to eliminate ZEA and its derivatives α-ZOL and β-ZOL was investigated as, also, the mechanisms involved. Strains were grown on Yeast Extract-Peptone-Dextrose medium supplemented with the mycotoxins and their elimination from medium was quantified over time by HPLC-FL. A significant effect on the concentration of ZEA was observed, as all the tested strains were able to eliminate more than 90% of the mycotoxin from the culture medium in two days. The observed elimination was mainly due to ZEA biotransformation into β-ZOL (53%) and α-ZOL (8%) rather than to its adsorption to yeast cells walls. Further, the biotransformation of α-ZOL was not observed but a small amount of β-ZOL (6%) disappeared from culture medium. ZEA biotransformation by yeasts may not be regarded as a full detoxification process because both main end-products are still estrogenic. Nonetheless, it was observed that the biotransformation favors the formation of β-ZOL which is less estrogenic than ZEA and α-ZOL. This metabolic effect is only possible if active strains are used as feed additives and may play a role in the detoxification performance of products with viable S. cerevisiae cells.

The present study was conducted to investigate the ability of Saccharomyces cerevisiae RC016 (Sc)-based feed additive to reduce liver toxicity, residual aflatoxin B1 (AFB1) levels and influence intestinal structure in broiler chickens fed chronic aflatoxin B1-contaminated diets. A total of 100 one-day-old male commercial line (Ross) broiler chickens were divided into 4 treatments, with 5 pens per treatment and 5 broiler chickens per pen. Birds were randomly assigned to 4 treatments, which were namely treatment 1 (T1), control diet (CD); T2, CD + Sc at 1 g/kg; T3, CD + AFB1 at 100 μg/kg; T4, CD + Sc at 1 g/kg + AFB1 at 100 μg/kg. The liver histopathology of broiler chickens fed diets with AFB1 showed diffused microvacuolar fatty degeneration. The addition of Sc showed normal hepatocytes similar to the control. The small intestine villi from AFB1 group showed atrophy, hyperplasia of goblet cells, prominent inflammatory infiltrate and oedema. In contrast, the small intestine villi from birds that received the yeast plus AFB1 showed an absence of inflammatory infiltrate, and atrophy; moreover, a lower number of goblet cells compared to the groups with AFB1 was observed. The morphometric intestine studies showed that a significant decrease (P < 0.05) in the crypt depth values when Sc was applied to AFB1-contaminated diets. Although the intestinal villus height and apparent adsorption area did not show significant differences (P > 0.05), there was a tendency to improve these parameters. The residual levels of AFB1 in livers were significantly reduced (P < 0.05) in the presence of the yeast. The present work demonstrated that the addition of Sc alone or in combination with AFB1 in the broiler chicken diets had a beneficial effect in counteracting the toxic effects of AFB1 in livers besides improving the histomorphometric parameters and modulating the toxic effect of AFB1 in the intestine.