Equilibrium Isotherm Approach to Measure the Capability of Yeast Cell Wall to Adsorb Clostridium perfringens

Yeast cell wall (YCW) products are currently used as substitutes to antibiotic growth promoters, to improve animal performances, and to reduce the incidence of infectious diseases in livestock. They are claimed to bind enteropathogens, thus interfering with their colonization in the intestinal mucosa. Although the anti-infectious activity of YCW products on Gram-positive pathogens like Clostridium perfringens has been reported in vivo, in vitro evidences on the adsorption of C. perfringens by YCW fractions are not yet available. Preliminary results showed that purified YCW products exert antimicrobial activity toward C. perfringens. Using the adsorption isotherm approach, we measured the ability of YCW products in adsorbing C. perfringens, thus reducing its viability. Dosages of YCW products >1 mg/mL adsorbed 4 Log colony-forming unit (CFU)/mL of C. perfringens in buffered solution. The maximum adsorption of the bacterium was reached in 3 h, whereas only one product of four YCW products retained the adsorption up to 6 h. The analysis of equilibrium isotherms and adsorption kinetics revealed that all products adsorb C. perfringens in a dose- and time-dependent manner, with high affinity and capacity, sequestering up to 4 Log CFU/mg of product. The determination of adsorption parameters allows to differentiate among adsorbents and select the most efficient product. This approach discriminated among YCW products more efficiently than the antimicrobial assay. In conclusion, this study suggests that the ability of YCW products in reducing C. perfringens viability can be the result of an adsorption mechanism.