Aflatoxin B-1 binding by a mixture of Lactobacillus and Propionibacterium: In vitro versus ex vivo

Aflatoxin B-1 (AFB(1)) is a well-known carcinogen and reducing its bioavailability is of great interest for human and animal health. Several probiotic bacteria are able to bind AFB(1) in vitro, including Lactobacillus rhamnosus LC-705 and Propionibacterium freudenreichii subsp. shermanii JS. A mixture of these two probiotics is used by the food and feed industry as biopreservative (Bioprofit), making it a promising candidate for future applications. Consequently, this study aims to investigate the in vitro and ex vivo ability of this probiotic mixture to bind AFB(1). For in vitro experiments, probiotic mixture was suspended in an AFB(1) solution (5 mu M), incubated for 1 to 30 min, centrifuged, and AFB(1) residues were quantitated in supernatant and pellet. For ex vivo experiments, duodenal loops of chicks were ligated and injected with either AFB(1) solution alone or probiotic mixture suspension and AFB(1) solution. Lumen content was centrifuged and AFB(1) was quantitated in supernatant and pellet. Additionally, AFB(1) was extracted from duodenal tissue to calculate tissue uptake. In vitro, 57 to 66% of AFB(1) was removed from the solution by the probiotic mixture, but only 38 to 47% could be extracted from the bacterial surface. In ex vivo experiments, only up to 25% of AFB(1) was bound by bacteria, and tissue uptake of AFB(1) was significantly reduced when probiotic bacteria were present in the duodenal loop. Furthermore, the effect of intestinal mucus on the bacterial binding ability was investigated in vitro and was found to significantly reduce AFB(1) binding by the probiotic mixture. However, probiotic mixture could only retard but not prevent AFB(1) absorption in duodenal loops. Further work needs to assess the potential of probiotics in different experimental setups.