Binding Rather Than Metabolism May Explain the Interaction of Two Food-Grade Lactobacillus Strains with Zearalenone and Its Derivative ɑ́-Zearalenol

Abstract

The interaction between two Fusarium mycotoxins, zearalenone (ZEN) and its derivative ␣-zearalenol (␣-ZOL), with two food-grade strains of Lactobacillus was investigated. The mycotoxins (2 g ml ؊1 ) were incubated with either Lactobacillus rhamnosus strain GG or L. rhamnosus strain LC705. A considerable proportion (38 to 46%) of both toxins was recovered from the bacterial pellet, and no degradation products of ZEN and ␣-ZOL were detected in the high-performance liquid chromatograms of the supernatant of the culturing media and the methanol extract of the pellet. Both heat-treated and acid-treated bacteria were capable of removing the toxins, indicating that binding, not metabolism, is the mechanism by which the toxins are removed from the media. Binding of ZEN or ␣-ZOL by lyophilized L. rhamnosus GG and L. rhamnosus LC705 was a rapid reaction: approximately 55% of the toxins were bound instantly after mixing with the bacteria. Binding was dependent on the bacterial concentration, and coincubation of ZEN with ␣-ZOL significantly affected the percentage of the toxin bound, indicating that these toxins may share the same binding site on the bacterial surface. These results can be exploited in developing a new approach for detoxification of mycotoxins from foods and feeds.Zearalenone (ZEN) (Fig. 1) is a nonsteroidal estrogenic mycotoxin produced by several species of Fusarium (F. graminareum, F. crookwellemse, F. culmorum, and F. semitectum) which primarily colonize maize and also colonize, to a lesser extent, barley, oats, wheat, and sorghum (12,17,20,30). The level of ZEN in human food can be as high as 289 g/g (15, 31). Several derivatives of ZEN, including ␣-zearalenol (␣-ZOL) and ␤-zearalenol (␤-ZOL) as well as monohydroxylated, dihydroxylated, and formylated ZEN, have been isolated from cultures of Fusarium (27).ZEN has predominantly estrogenic properties that are manifested in female swine, cattle, and sheep as reproductive problems (13). Concentrations of 1 to 5 g of ZEN/g of feed are sufficient to produce clinical symptoms in swine (29). The alpha-reduction of the keto group increases the estrogenic activity of ZEN. ␣-ZOL has about 10 to 20 times the activity of ZEN and some 100 times that of ␤-ZOL (24).ZEN and its metabolites act as growth stimulants, and their occurrence in food has been related to the early onset of puberty in children from Puerto Rico (28). The cooccurrence of ZEN and trichothecenes in contaminated corn has been correlated with the incidence of human esophageal cancer in China (8). The estimated safe human intake of ZEN has been reported to be 0.05 g/kg of body weight/day (17).A small number of studies on the degradation and biotransformation of ZEN by various microorganisms have been published. El-Sharkawy et al. (7) investigated the conversion of ZEN by seven genera (23 species) of microorganisms. The metabolites formed included ␣-ZOL and ␤-ZOL and another polar metabolite, zearalenone-4-O-sulfate. ZEN was reduced stereoselectively by cultures of Candida tropicalis, Zygosaccharomyces...

Effects of multispecies probiotic supplementation on intestinal microbiota in irritable bowel syndrome

“…Inhibition of pathogen adhesion, 29 production of an antimicrobial substance, 30 binding of heavy metals and aflatoxins 31,32 Propionibacterium freudenreichii ssp. …”

Biological Control of Molds and Mycotoxins in Foods

“…Even though the authors have not discussed, the difference observed between the inhibitory effect in the presence and absence of the LAB cells could be attributed to a binding or sequestration effect caused by the LAB cells. Binding of mycotoxins by LAB has been well documented in the literature (53,54,55,56,57).…”

“…L. rhamnosus was evaluated for its potential to remove or degrade zearalenone and α-zearalenol, and both viable and non-viable cells (heat and acid treated) were able to remove about 50% of the toxin from solution, indicating that binding rather than metabolism was the mechanism in action (55). This finding was substantiated by the lack of detection of degradation products in solution.…”

“…This finding was substantiated by the lack of detection of degradation products in solution. When L. rhamnosus was exposed to both toxins at the same time, its ability to remove zearalenone and α-zearalenol from solution was significantly reduced, indicating that these toxins may share the same binding site on the bacterial cell (55).…”

Fermentation Processes Using Lactic Acid Bacteria Producing Bacteriocins for Preservation and Improving Functional Properties of Food Products

“…Both heat-treated and acid-treated bacteria were capable of removing the toxins, indicating that binding, not metabolism is the mechanism by which the toxins are removed from the media (El-Nezami et al, 2002). Zearalenone was also degraded by a mixed bacterial culture.…”