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Identification of Dairy Fungal Contamination and Reduction of Aflatoxin M1 Amount by Three Acid and Bile Resistant
F Faghihi Shahrestani1, M Tajabadi Ebrahimi2, M Bayat1,1
1Department of Pathobiology, Faculty of Veterinary Specialized Science, Science and Research Branch, Islamic Azad University, Tehran, Iran.
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.
Insights
This study found that three lactic acid bacteria (LAB) strains significantly reduce carcinogenic Aflatoxin M1 (AFM1) in traditional milk and cheese. These findings offer a promising natural strategy for improving dairy product safety.
Area of Science:
- Food Science
- Microbiology
- Toxicology
Background:
- Aflatoxins (AFs), particularly Aflatoxin M1 (AFM1), are carcinogenic contaminants found in cow's milk even after pasteurization.
- AFM1 poses a significant public health risk, necessitating effective strategies for its reduction in dairy products.
- Lactic acid bacteria (LAB) have shown potential in mitigating AFs, but routine application is limited.
Purpose of the Study:
- To evaluate the efficacy of three selected LAB strains in reducing AFM1 levels in traditional Iranian milk and cheese.
- To compare AFM1 contamination levels with the National Iranian Standard.
- To identify and characterize LAB strains with significant AFM1-reducing capabilities.
Main Methods:
- Collected 85 traditional milk and cheese samples from Shiraz, Iran.
- Screened 50 LAB strains for antifungal properties and bile salt resistance.
- Assessed AFM1 reduction by selected LAB strains in spiked samples and compared with natamycin.
- Sequenced and registered effective LAB strains in the NCBI database.
- Analyzed AFM1 levels using Chi-square test at a 95% confidence level.
Main Results:
- Fifteen samples exceeded the National Iranian Standard for AFM1, with identified fungal contaminants including Penicillium spp. and Aspergillus niger.
- Three LAB strains demonstrated significant AFM1 reduction: Lactobacillus fermentum CECT562 (T) (0.05 reduction), Lactobacillus brevis ATCC14869 (T) (0.03 reduction), and Enterococcus faecium LMG 11423 (T) (0.03 reduction).
- The selected LAB strains showed a notable decrease in AFM1 levels in traditional dairy matrices.
Conclusions:
- The three selected LAB strains, Lactobacillus fermentum, Lactobacillus brevis, and Enterococcus faecium, effectively reduce AFM1 in traditional milk and cheese.
- Implementing the National Iranian Standard more rigorously is crucial for controlling dairy product safety.
- These LAB strains represent a viable natural approach for mitigating AFM1 contamination in dairy products.
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