Aflatoxin B1 Binding by a Mixture of Lactobacillus and Propionibacterium: In Vitro Versus Ex Vivo

Abstract

Aflatoxin B1 (AFB) 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 AFB1 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 AFB1. For in vitro experiments, probiotic mixture was suspended in an AFB1 solution (5 microM), incubated for 1 to 30 min, centrifuged, and AFB1 residues were quantitated in supernatant and pellet. For ex vivo experiments, duodenal loops of chicks were ligated and injected with either AFB1 solution alone or probiotic mixture suspension and AFB1 solution. Lumen content was centrifuged and AFB1 was quantitated in supernatant and pellet. Additionally, AFB1 was extracted from duodenal tissue to calculate tissue uptake. In vitro, 57 to 66% of AFB1 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 AFB1 was bound by bacteria, and tissue uptake of AFB1 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 AFB1 binding by the probiotic mixture. However, probiotic mixture could only retard but not prevent AFB1 absorption in duodenal loops. Further work needs to assess the potential of probiotics in different experimental setups.

Lactobacillus rhamnosus Strain GG Reduces Aflatoxin B 1 Transport, Metabolism, and Toxicity in Caco-2 Cells

“…Chronic aflatoxin exposure has also been associated with growth faltering (12,13), and in independent studies from the Gambia, intestinal enteropathy, characterized by "intestinal leakiness," has been associated with early childhood growth faltering (2,25). Given that (i) enterocytes have the metabolic enzymes to generate the reactive aflatoxin epoxide (4), (ii) aflatoxin exposure is frequent at high levels (38,39) in regions reporting an association between growth faltering and intestinal leakiness (2,25), and (iii) aflatoxin exposure has been associated with infant growth faltering (13,14,39), it is plausible that observations of aflatoxin-associated growth faltering may be explained at least in part by a direct action of the aflatoxin epoxide within the enterocytes. To assess this direct toxic effect of AFB 1 on the Caco-2 monolayer, we studied its effect on monolayer integrity, using TER measurements.…”

Dairy Propionibacteria: Less Conventional Probiotics to Improve the Human and Animal Health

“…Kinetics of adsorption and desorption of Aflatoxin B1 by viable and no viable bacteria have also been determined [215]. Tested ex vivo in the intestinal lumen of chicks, there was a 63% reduction in the uptake of AFB1 by the intestinal tissue in the presence of P.freudenreichii JS and its binding ability seems to be even better than in vitro results [211]. When combined with L. rhamnosus LC-705, 57-66% of AFB1 was removed by the probiotic mixture in vitro whereas 25% of AFB1 was bound by bacteria in ex vivo experiments being tissue uptake of AFB1 also reduced when probiotic bacteria were present in the duodenal loop [211] Intestinal mucus significantly reduced AFB1 binding by the probiotic mixture and viceversa (preincubation with AFB1 reduced mucus binding) [216].…”

“…The capacity of Propionibacterium freudenreichii strain JS used alone and combined with lactobacilli (L. rhamnosus GG or LC705) to remove mycotoxins has been studied by in vitro [210][211][212], ex vivo [211] and in vivo assays [213][214]. It has been determined that both viable and heat-killed forms of propionibacteria are able to remove efficiently aflatoxin B1, fumonisins and trichotecenes from liquid media.…”

“…Mycotoxins are also forage contaminants, which impair animal performances and health. Several probiotic bacteria, commonly used in food products, have been shown to bind Aflatoxin B1 and the toxins produced by Fusarium sp such as zearalenone, fumonisins B1 and B2 and trichothecenes, like deoxynivalenol (DON), nivalenol (NIV) and T-2 toxin (T-2) preventing their absorption in the gastrointestinal tracts of animals and humans [210][211][212][213][214].…”

Recent Trends in Microbiological Decontamination of Aflatoxins in Foodstuffs

“…Bioavailability may be reduced by enterosorption, which is done by adding nutritionally inert adsorbent compounds to the diet. These compounds are mycotoxin sequestrants, and prevent the toxin from being absorbed in the gastrointestinal tract of the animals, making its distribution to the target organs impossible [14]. This method has limited practical use, due to the safety of the adsorbent agents used, and the difficulty in applying them to human foods [15].…”