Alkali extraction of beta-D-glucans from Saccharomyces cerevisiae cell wall and study of their adsorptive properties toward zearalenone
2004
Yiannikouris, A. | Francois, J. | Poughon, L. | Dussap, C.G. | Bertin, G. | Jeminet, G. | Jouany, J.P.
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 β-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 °C with a constant quantity of alkali-soluble or alkali-insoluble β-D-glucans isolated from yeast cell walls, and the amount of adsorbed zearalenone was measured. Given that the alkali solubility of β-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 (~16%), it was concluded that the three-dimensional structure strongly influences the adsorption process. The alkali insolubility of β-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 β(1,3)-D-glucan and β(1,6)-D-glucan compositions of the two alkali-extracted fractions and their involvement in the adsorption process are discussed.
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