Dairy products contain different kinds of chemical pollutants i.e. antibiotics, pesticides, mycotoxins and dioxins. Fungal toxins such as aflatoxins would enter from animal feed into their milk also dairy products thus, it could be a hazardous issue in dairy industries. Milk and its products are consumed commonly by most of the people and aflatoxin M1 contamination can seriously threaten their health, particularly children and elderly. Since aflatoxin is resistant to common thermal processes like pasteurization also disposing of contaminated products could lead to environmental problems, further efforts have been done to remove this contaminant from milk or other dairy products completely or at least to some extent. Food safety issues, product quality reduction also low efficiency and high costs of the physicochemical processes to remove mycotoxins limit applying them in industrial scale. Thus, extensive researches have been conducted to replace physicochemical methods with safer and more efficient ones. According to the literatures, biological methods seem more adequate to achieve this aim and remove aflatoxin M1. One of the best strategies to reduce toxin amount or prevent entering to the dairy products is taking advantage of lactic acid bacteria which can remove toxins by binding them to their cell wall. In this study, probiotic yogurts were firstly prepared by Lactobacillus acidophilus LA-5 in combination with or without yogurt starter culture and survival of the probiotic bacterium was evaluated. The ability of Lactobacillus acidophilus LA-5 to remove aflatoxin M 1 in probiotic yogurt, producing from contaminated milk in three levels of 0.1, 0.5 and 0.75 µg/L aflatoxin M 1 , was evaluated and compared to the control (yogurt produced from the traditional yogurt starter culture). The results showed that Lactobacillus acidophilus LA-5 is well enough resistant against yogurt starters with just one log reduction during storage (21 days) at 4 °C and the bacterial count of this strain reached at 10 7 CFU/g. This characteristic support this product as a probiotic yogurt. The toxin reduction has been evaluated by competitive ELISA and confirmed by HPLC. This study showed Lactobacillus acidophilus LA-5 probiotic bacterium could reduce the level of aflatoxin M1 above 90% in comparison with the control samples (23/46, 75/37 and 82/38 %, respectively). Statistical analysis also demonstrated that the storage time and concentration of inoculated aflatoxin in media have a significant effect on the toxin reduction by yogurt starter cultures and probiotic bacteria. It is shown that employing Lactobacillus acidophilus LA-5 in comparison with non-biological methods not only is more beneficial but also able to reduce the aflatoxin contamination of the dairy products without any side effects. Moreover, detoxification ability of the LA-5 (individually or combined) is more efficient than the conventional yogurt starter cultures in different levels of aflatoxin.
