191 The aggregation capacity of oligosaccharides from different yeast preparations to bind different pathogenic bacteria.

Abstract

An in vitro binding assay was used to measure the ability of 3 yeast products to bind bacteria. The products tested were: ethanol production derived S. cerevisiae (SC), hydrolyzed S. cerevisiae (HSC) and whole yeast cells derived from Pichia guilliermondii (Citristim®). All products were used at dose rates of 0.000, 0.025, 0.050, 0.075 and 0.100%. Six strains of Escherichia coli and six strains of Salmonella enterica ser. Enterica were tested. The 6 strains included 2 poultry, 2 swine, and 2 ruminant. Strains were incubated at 37 °C for 24 hours in Luria Agar plates (108 CFU/mL) before use. Gastric treatment was applied to mimic digestive process; products were treated with a pH of 2.5 and pepsin (1 mg/mL) solution and incubated at 37ºC for 2 hours. Test doses were then mixed with the microorganism suspension (1:1). Pure mannose (0.05M) served as positive control and results set as 100% aggregation. All suspensions were assessed as fresh preparations between slide and coverslip. A minimum of twenty microscopic fields for each determination were assessed. Doses of 0.000 to 0.075% for SC and HSC for all strains showed lower (P < 0.05) aggregation capacity compared with mannose. For poultry and swine strains, the highest dose of SC and HSC, and Citristim at 0.025% showed similar aggregation to mannose. Doses of Citristim of 0.050% and higher showed equal or better (P < 0.05) aggregation capacity compared with mannose for all strains. In conclusion, CitriStim at 0.025% was equally as effective as the standard, pure mannose. Above 0.050% CitriStim, the aggregation of pathogenic fimbriated bacteria was significantly better than SC and HSC (P < 0.05).