Factors affecting the sequestration of aflatoxin by Lactobacillus rhamnosus strain GG

The interaction of a potent carcinogen, aflatoxin B(1) (AFB(1)), with a probiotic strain of lactic acid bacteria, Lactobacillus rhamnosus strain GG (GG), has been investigated. The binding of AFB(1) to GG in the late exponential-early stationary phase was studied for viable, heat-killed and acid-killed bacteria. In general, viable, heat-killed and acid-killed GG responded in a similar manner. The effects of pronase E, lipase and m-periodate on AFB(1) binding and release were consistent with AFB(1) binding predominantly to carbohydrate components of the bacteria. The effect of urea suggested hydrophobic interactions play a major role in binding. Increasing concentration (0.01-1 M) of NaCl or CaCl(2) had minor effects on AFB(1) binding suggesting some involvement of electrostatic interactions. An increase in pH from 2.5 to 8.5 had no effect on AFB(1) binding but decreased binding of AFB(2a), possibly due to hydrogen bonding interactions.