Key role of teichoic acids on aflatoxin B₁binding by probiotic bacteria

Abstract

Aims: To assess the ability of five probiotic bacteria to bind aflatoxin B1 and to determine the key role of teichoic acids in the binding mechanism. Methods and Results: The strains were incubated in aqueous solutions containing aflatoxin B1 (AFB1). The amount of free toxin was quantified by HPLC. Stability of the bacteria–aflatoxin complex was evaluated by repeated washes with buffer. In order to understand the binding process, protoplasts, spheroplasts and cell wall components of two strains were analysed to assess their capacity to bind AFB1. Additionally, the role of teichoic acids in the AFB1 binding process was assessed. Lactobacillus reuteri strain NRRL14171 and Lactobacillus casei strain Shirota were the most efficient strains for binding AFB1. The stability of the AFB1–bacteria complex appears to be related to the binding ability of a particular strain; AFB1 binding was also pH‐dependent. Our results suggest that teichoic acids could be responsible for this ability. Conclusions: Our results provide information concerning AFB1 binding by previously untested strains, leading to enhanced understanding of the mechanism by which probiotic bacteria bind AFB1. Significance and Impact of the Study: Our results support the suggestion that some probiotic bacteria could prevent absorption of aflatoxin from the gastrointestinal tract.

Reduction of Aflatoxin M1 Levels during Ethiopian Traditional Fermented Milk (Ergo) Production

“…This evidence strongly supports the first mechanism that the toxin is removed predominantly by noncovalent binding with the chemical components of the bacterial cell wall. This mechanism is further evidenced by the reports of HernandezMendoza et al (2009) [41] who demonstrated that cell components such as teichoic acids are the possible binding sites for AFB1.…”

“…bulgaricus, and Bifidobacterium lactis), alone or in combination, in UHT (ultrahigh temperature) skim milk. On the other hand, other researchers showed that the binding ability of AFB1 to LAB is strain specific [18,34,41]. Regarding the effect of pH change during ergo fermentation, Elsanhoty et al (2014) [18] considered the pH change during fermentation as a factor affecting the binding interaction and showed an increase in the level of AFM1 reduction by the decrease in pH during bacterial treatment.…”

“…The second is the degradation through hydrolysis of the lactone ring of the toxin by the developing acid during the fermentation [37]. However, numerous recent investigations on the possible mechanisms of AFM1 removal by treatment with dairy strains of LAB and bifidobacteria suggested a physical union, adhesion to bacterial cell wall components (polysaccharides and peptidoglycans), instead of degradation by hydrolysis or covalent binding [35,[37][38][39][40][41]. For instance, Bovo et al 2013 [35] demonstrated AFM1 binding by Saccharomyces cerevisiae strain and a pool of three LAB strains (Lactobacillus rhamnosus, Lactobacillus delbrueckii spp.…”

Recent Trends in Microbiological Decontamination of Aflatoxins in Foodstuffs

“…In reference [57] authors explained that the integrity of the bacterial cell wall is important in the process of toxin removal by both viable and non-viable cells. In their study of AFB 1 , they observed that both the bacterial cell wall and its purified fragments were able to remove aflatoxin from the medium.…”

Antimicrobial Effect of Lactobacillus reuteri on Cariogenic Bacteria Streptococcus gordonii, Streptococcus mutans, and Periodontal Diseases Actinomyces naeslundii and Tannerella forsythia

“…Most interesting for the control of periodontal diseases is LAB, with antimicrobial and anti-inflammatory properties such as L. reuteri, L. fermentum, and L. casei Shirota [15,16]. Of these bacteria, L. reuteri is most interesting for the control of oral microbiota as it produces reuterin, a wide spectrum antimicrobial agent [17].…”