Alkali Extraction of β-d-Glucans from Saccharomyces cerevisiae Cell Wall and Study of Their Adsorptive Properties toward Zearalenone

Abstract

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.

Yeast cell based feed additives: studies on aflatoxin B1and zearalenone

“…The mechanism of binding by β-Dglucans has been investigated by Yiannikouris and co-workers and has been discussed in several publications, e.g. (Yiannikouris et al 2004a;Yiannikouris et al 2006;Yiannikouris et al 2004b;Yiannikouris et al 2004c). It was shown that it is important to differentiate between the adsorption affinity of whole yeast cell wall and processed cell wall.…”

“…A further factor influencing the binding ability is the presence of chitin which stiffens the cell wall structure and restricts access of e.g. ZON to the binding sites of β-D-glucans (Yiannikouris et al 2004c). Therefore, the preparation of the cell wall material prior to its application as a mycotoxin binder is of major importance and greatly influences the adsorption ability of the final product.…”

Recent Trends in Microbiological Decontamination of Aflatoxins in Foodstuffs

“…Protective effect against aflatoxins produced by yeasts was confirmed in rats. However, when yeast cells were inactivated by heat, they were inefficient [80] but when glucomannanes extracted from the cell wall of yeasts were used, there was an increase in the efficiency of the bond with AFB 1 , OTA and T-2 toxin [81][82][83][84], individually or in combination [75,79,85,86]. The addition of SC in the diet reduced AFB 1 toxic effects in chickens [72,87].…”

Yeast (Saccharomyces cerevisiae) Glucan Polysaccharides – Occurrence, Separation and Application in Food, Feed and Health Industries

“…The second major yeast cell wall polysaccharide, (1→3)(1→6)--D-glucan, might also contribute to yeast cell wall biological properties (section 5 of this chapter), but its major role in animal nutrition is its ability to bind mycotoxins and detoxify animal feed. The (1→3)(1→6)--D-glucan is a part of the cell wall's "triple helix tridimensional structure, with spring-like mechanical properties, responsible for yeast cell wall strength and ability to absorb toxins" (Yannikouris et al, 2004) (see section 2, this chapter). Toxins occurring in plant-derived animal feed belong to one of two groups.…”