Alkali extraction of beta-d-glucans from Saccharomyces cerevisiae cell wall and study of their adsorptive properties toward zearalenone.
The isolated cell wall of Saccharomyces cerevisiae has some capacity to adsorb zearalenone (affinity near 30%) and reduce the bioavailability of toxins in the digestive tract. The adsorption process was quantified in vitro, and the data obtained when plotted with Hill's equation indicated a cooperative process. The model showed that the adsorption capacity was related to the yeast cell wall composition. This work focused on the role of various beta-d-glucan types in the efficacy of zearalenone adsorption by yeast cell wall and sought to elucidate some of the adsorption mechanisms. Zearalenone was mixed at 37 degrees C with a constant quantity of alkali-soluble or alkali-insoluble beta-d-glucans isolated from yeast cell walls, and the amount of adsorbed zearalenone was measured. Given that the alkali solubility of beta-d-glucans is a determining factor for their three-dimensional conformation and that the alkali-insoluble fraction had a greater affinity (up to 50%) than the alkali-soluble fraction ( approximately 16%), it was concluded that the three-dimensional structure strongly influences the adsorption process. The alkali insolubility of beta-d-glucans led to the formation of single and/or triple helices, which have been identified as the most favorable structures for zearalenone adsorption efficacy. The beta(1,3)-d-glucan and beta(1,6)-d-glucan compositions of the two alkali-extracted fractions and their involvement in the adsorption process are discussed.
Yiannikouris
Alexandros
A
UR1053 INRA, Unité de Recherches sur les Herbivores Centre de Clermont-Theix, 63122 St-Genès Champanelle, France.
François
Jean
J
Poughon
Laurent
L
Dussap
Claude-Gilles
CG
Bertin
Gérard
G
Jeminet
Georges
G
Jouany
Jean-Pierre
JP
D000327:Adsorption; D002473:Cell Wall / Q000737:chemistry*; D005936:Glucans / Q000737:chemistry* / Q000302:isolation & purification*; D006863:Hydrogen-Ion Concentration; D012441:Saccharomyces cerevisiae / Q000737:chemistry*; D012995:Solubility; D015025:Zearalenone / Q000737:chemistry*
D005936:Glucans; D015025:Zearalenone