Saccharomyces cerevisiae Cell Wall Isolates are Potential Inhibitors of Bacterial Growth

Abstract

Saccharomyces cerevisiae cell wall components are thought to bind and help pass pathogenic bacteria, such as E. coli, through the intestines 1. The binding between bacteria and S. cerevisiae is thought to occur between type‐1 mannose specific fimbriae, a common feature of pathogenic bacteria, and the mannoproteins that comprise 30–50% of the cell wall of S. cerevisiae by weight 2, 3, 4. With the fimbriae bound to mannoproteins, bacteria are unable to adhere to the walls of the intestine and thus, no colonization occurs. This interaction provides a potential antibiotic free method to prevent E. coli infection. The goals of this project are two‐fold. First, to develop a cell wall harvesting procedure and characterize the cell wall fractions. Second, to evaluate the binding interaction of S. cerevisiae with E. coli and its effect on E. coli proliferation. A cell wall isolation procedure has been optimized using temperature induced autolysis of a cell culture at 50 °C and pH 5.0 for 24 hours followed by purification washes with salt solutions. Cell wall fractions have been characterized using the Bradford assay, Coomassie stained SDS gels, and Western blot analysis employing the lectin Concanavalin A antibody to detect mannose. The cell wall fractions have been found to contain high levels of mannoproteins. An in‐vitro binding assay, adapted from Ganner et al. 2013, has been employed to evaluate the interaction between the cell wall fractions and E. coli. Cell wall coated microplate wells display a faster progression to log phase than controls due to the cell wall‐fimbriae binding interaction increasing retention of initial colony forming units. In‐vivo, a stronger binding interaction would inhibit bacterial infection by disrupting initial attachment of E. coli to the intestinal lining. Work is currently being performed to better understand factors influencing the binding mechanism as previous studies have indicated an unclear connection between total mannoprotein content and binding capacity. 2Support or Funding InformationSJFC Internal funds