Identification of Dairy Fungal Contamination and Reduction of Aflatoxin M1 Amount by Three Acid and Bile Resistant Probiotic Bacteria.

Abstract

Aflatoxins (AFs) released by fungi are observed in the cow’s milk even after pasteurization. Aflatoxin M1 (AFM1) has particularly an incredible clinical significance, as a critical carcinogenic agent for humans. Several strategies have been implemented for lowering the AFM1 amount, such as the employment of probiotics, particularly lactobacilli or lactic acid bacteria (LAB). However, this strategy has not been applied routinely until today. This study aimed to evaluate the effect of three LABs on the reduction of AFM1 in traditional milk and cheese samples. In total, 85 milk (n=45) and cheese (n=40) samples were obtained from the open markets of Shiraz, Iran, from February to June 2018. Additionally, the AFM1 levels were evaluated, compared to those of the National Iranian Standard. The data were then analyzed in SPSS software (version 20) through the Chi-square test. Statistical analysis was performed at a 95% confidence level (p-value of <0.00001). Out of 50 purchased LABs, the efficient antifungal property and resistance to bile salts were observed in five strains. The mean value of these five strains was calculated after adding 5 ppm AFM1, compared to natamycin. The strains with a reduction in AFM1 level were sequenced and registered in the NCBI database.In total, 15 samples with contamination higher than the allowed limit included Penicillium spp, Aspergillus niger, Saccharomyces cerevisia, Saccharomyces paradoxus, and Yarrowia lipolytica.The results also showed reduced AFM1 levels in three LAB-treated strains. Lactobacillus fermentum CECT562 (T), Lactobacillus brevis ATCC14869 (T), and Enterococcus faecium LMG 11423 (T) had this capability to 0.05, 0.03, and 0.03 respectively. The National Iranian Standard should be implemented to have control over traditional dairy products with more care. The three LABs selected in the current study revealed a significant effect on reducing AFM1 levels in traditional milk and cheese.