Effect of citrus pulp on the viability of Saccharomyces boulardii in the presence of enteric pathogens

Authors: WILSON, JESSICA - Mississippi State University; MCLAURIN, TYLER - Mississippi State University; Carroll, Jeffery - Jeff Carroll; SHIELDS-MENARD, SARA - Mississippi State University; SCHMIDT, TY - University Of Nebraska; Callaway, Todd; DONALDSON, JANET - Mississippi State University

Submitted to: Agriculture, Food and Analytical Bacteriology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/16/2013
Publication Date: 12/1/2013
Publication URL: https://handle.nal.usda.gov/10113/61137
Citation: Wilson, J.G., Mclaurin, T.C., Carroll, J.A., Shields-Menard, S., Schmidt, T.B., Callaway, T.R., Donaldson, J.R. 2013. Effect of citrus pulp on the viability of Saccharomyces boulardii in the presence of enteric pathogens. Agriculture, Food and Analytical Bacteriology. 3:303-311.

Interpretive Summary: Saccharomyces cerevisiae subtype boulardii is a dietary supplement that improves animal health and reduces the impact of enteric pathogens in cattle and swine. Citrus by-products are also fed as dietary supplements that have the additional benefit of inhibiting enteric pathogens. Previous research identified that S. boulardii supplementation with citrus pulp reduced (P < 0.01) the average daily gain of weanling pigs challenged with Salmonella enterica, suggesting that citrus pulp reduced the effectiveness of S. boulardii. Therefore, in the present study, an in vitro analysis was conducted of the activity of S. boulardii in swine fecal microbial media supplemented with citrus pulp. Citrus pulp inclusion reduced (P < 0.01) populations of S. boulardii by 1.6 log10 within 48 h post-exposure, suggesting potential antifungal properties. S. boulardii directly affects populations of Salmonella. Collectively, these results suggest that citrus pulp reduces the viability of S. boulardii and that the subsequent effects of this interaction on enterics are varied. These data strongly suggest that caution should be exercised in providing citrus pulp to livestock being fed diets supplemented with live yeast probiotics.

Technical Abstract: Saccharomyces cerevisiae subtype boulardii is frequently used as a dietary supplement to promote intestinal health and reduce the impact of growth of enteric pathogens in livestock, including cattle and swine. Citrus by-products are also fed as dietary supplements that have the additional benefit of inhibiting the growth of enteric pathogens. However, previous research identified that supplementation of S. boulardii to feed containing citrus pulp reduced (P < 0.01) the average daily gain of weanling pigs challenged with Salmonella enterica, suggesting that citrus pulp reduces the effectiveness of S. boulardii. To investigate this possibility, an in vitro analysis was conducted on the activity of S. boulardii in swine fecal microbial media supplemented with citrus pulp. Citrus pulp inclusion reduced (P < 0.01) populations of S. boulardii by 1.6 log10 within 48 h post-exposure, suggesting that this product may exhibit antifungal properties. Co-incubation of Salmonella with S. boulardii reduced populations of the yeast by 1.5 log10 (P < 0.001). Inclusion of citrus pulp did not contribute to a reduction of yeast populations but did reduce populations of Salmonella. These data suggest that S. boulardii directly affects populations of Salmonella. The cell lysate from S. boulardii was also found to provide a carbon source that was utilizable by E. coli, but not Salmonella. Together, these results suggest that citrus pulp reduces the viability of S. boulardii and that the subsequent effects of this interaction on enterics are varied. Though further research is needed to determine how citrus pulp influences the activity of S. boulardii in vivo, these data strongly suggest caution should be exercised in providing citrus pulp to livestock being fed diets supplemented with live yeast probiotics.