Dairy fungal contamination and reduction of aflatoxin M1 amount by three acid– and bile–resistant introductory probiotics versus Natamycin

Document Type: Original Articles

Authors

1 Department of Pathobiology, Faculty of Veterinary Specialized Science, Science and Research Branch, Islamic Azad University, Tehran, Iran.

2 Department of Science, Faculty of Basic Science, Tehran Central branch, Islamic Azad University, Tehran, Iran

3 Tehran University of Medical Science, Tehran, Iran

4 Department of Food of Microbiology, Faculty of Veterinary Specialized Science, Science and Research Branch, Tehran Islamic Azad university, Tehran, Iran.

Abstract

Background: Aflatoxins (AFs) released by fungi, withstand in the cow’s milk even after pasteurization. Aflatoxin M1 (AFM1) has particularly an incredible clinical significance, as a critical carcinogenic agent for human. Several strategies have been implemented for lowering AFM1 amount, such as the employment of probiotics; particularly those Lactobacilli or lactic acid bacteria (LAB). Nevertheless, this strategy not been applied routinely until today.
Objectives: In this study, we designed to evaluate the effect of three LABs on reduction of AFM1 in traditional milk and cheese.
Materials and Methods: In this study, 45 milk samples and 40 cheese samples were obtained from open market of Shiraz city in the course of Feb–June 2018. Additionally, the AFM1 levels were compared to the National Iranian Standard and were analyzed by SPSS version 20 and chi-square statistical analysis with about 95% accuracy and significant level (p-value<0.00001). Of 50 LABs purchased, the efficient antifungal property, and resistance to bile salts was observed in 5 strains. These 5 strains were tested for mean afterward adding of 5 ppm AFM1, compared to natamycin. The strains with reduction in AFM1 level were sequenced and registered in NCBI database.
Results: Fifteen samples had contamination higher than allowed limit having Penicillium spp, Aspergillus niger, Saccharomyces cerevisia, Saccharomyces paradoxus and Yarrowia lipolytica. The results outlined reduced AFM1 level in three LAB-treated strains. Lactobacillus fermentum CECT562 (T), Lactobacillus brevis ATCC14869 (T), Enterococcus faecium LMG 11423(T) had this capability to 0.05, 0.03, and 0.03 respectively.
Discussion: The National Iranian Standard obedience must be performed and controlled with more care in traditional dairy products. The three LABs selected in the current study revealed important influence on reducing AFM1 level in the traditional milk and cheese.

Keywords