To provide in vitro evidences on the antimicrobial effect of yeast cell wall (YCW), the effectiveness of YCW fractions in inhibiting the growth of several C. perfringens strains was quantitatively determined. The bacterium was grown in the presence of different YCW fractions at different concentration levels. The effect of YCW fractions on the growth parameters was analyzed. One product out of four materials was selected as the best candidate for C. perfringens inhibition. The selected product, at an optimal dosage of 1.25 mg/mL, increased the lag phase duration, and reduced the maximum growth rate and the final cell count in a significant manner with respect to the control. The adsorption of the pathogen to YCW was studied using the isotherm adsorption approach. The effect of YCW dosage, incubation time, and bacterial concentration on the adsorption was evaluated. The study proved that the product adsorbed C. perfringens cells in a dose and time dependent manner. Equilibrium isotherms showed that the cell adsorption onto the product was fast, stable over the time, and occurred with high affinity and capacity. The selected product sequestered up to 104 cells of C. perfringens per mg. To the best of our knowledge, this is the first report showing the in vitro efficacy of yeast fraction products to inhibit the growth of C. perfringens, and to reduce the culturable cells by an adsorption process. The in vitro approach proposed herein is as a powerful tool to study the adsorption of aerobic or anaerobic pathogens by eubiotics.
Keywords: yeast cell wall, antimicrobial, Clostridium, adsorption, feed additives