Screening of Lactobacillus casei strains for their ability to bind aflatoxin B1

It has been proposed that the consumption of lactic acid bacteria capable of binding or degrading food-borne carcinogens would reduce human exposure to these deleterious compounds. In the present study, the ability of eight strains of Lactobacillus casei to bind aflatoxin B-1 in aqueous solution was investigated. Additionally, the effect of addition of bile salts to the growth medium on aflatoxin B-1 binding was assessed. The eight strains tested were obtained from different ecological niches (cheese, corn silage, human feces, fermented beverage). The strains exhibited different degrees of aflatoxin binding; the strain with the highest AFB(1) binding was L. casei L30. which bound 49.2% of the available aflatoxin (4.6 mu g/mL). In general, the human isolates bound the most aflatoxin B-1 and the cheese isolates the least. Stability of the bacterial-aflatoxin complex was assessed by repeated washings. Binding was to a limited degree (0.6-9.2% release) reversible; the L. casei 7R1-aflatoxin B-1 complex exhibited the greatest stability. L. casei L30, a human isolate. was the strain least sensitive to the inhibitory effects of bile salts. Exposure of the bacterial cells to bile significant increased aflatoxin B-1 binding and the differences between the strains was reduced. (C) 2009 Published by Elsevier Ltd.