Aflatoxin Binding by Probiotics

Aflatoxin B1 (AFB1) is a food contaminant with detrimental impact on human and animal health. Intervention approaches focus on preand post-harvest measures to reduce AFB1 levels in crops or on the individual level to modulate bioactivation and excretion of AFB1 or reduce its bioavailability. Probiotic bacteria have been identified as a potential means to reduce availability of AFB1 as well as other food contaminants. In this study we used both in vitro and in vivo approaches to study the interplay between probiotic bacteria and AFB1 in the intestinal environment. Initially, the binding ability of several probiotics was explored in vitro. Intestinal mucus was found to compete with AFB1 binding sites on the surface of bacteria. This should be taken into consideration when choosing a probiotic for AFB1 binding, as was also evident from our studies in the duodenal loop of chicks, where different probiotics with similar binding capacity in vitro, had different effects on AFB1 absorption from the intestine. As a subsequent step, rats were dosed orally with AFB1 and probiotics and fecal excretion of AFB1 was significantly but transiently increased by probiotic dosing, possibly reflecting a reduction in absorption of AFB1 from the intestinal lumen. Furthermore, AFB1 induced hepatotoxicity was slightly reduced and weight loss was alleviated in rats dosed with probiotics. To study whether the AFB1 binding by the probiotic bacteria has an effect on its transport and toxicity to the intestinal tissue, Caco-2 cells were incubated with AFB1 and direct toxic effects on epithelial integrity and genotoxic effects were observed in the presence and absence of the bacteria. When the probiotic bacteria were added, AFB1 toxicity could be reduced. In conclusion, these studies clearly show the protective effects of probiotic bacteria against AFB1 induced intestinal and systemic toxicity via binding AFB1 and reducing its transport in different test systems. National Library of Medicine Classification: QW 125.5.P7, QW 142.5.A8, QW 630, WI 402 Medical Subject Headings: Aflatoxin B1/metabolism; Aflatoxin B1/toxicity; Caco-2 Cells; Chickens; Duodenum; Feces; Intestinal Absorption; Intestines/metabolism; Lactobacillus; Mucus/microbiology; Propionibacterium; Probiotics; Rats; Urine