|Tu, Shu i|
Submitted to: Journal of Food Safety
Publication Type: Peer reviewed journal
Publication Acceptance Date: 2/17/2011
Publication Date: 8/1/2011
Citation: Medina, M.B., Uknalis, J., Tu, S. 2011. Effects of sugar addition in luria bertania (LB) media on Escherichia coli 0157:H7. Journal of Food Safety. 31(3):386-394. Interpretive Summary: Human pathogenic bacteria, E. coli O157:H7 produces Shiga-like toxins (SLT) that causes hemolytic uremic syndrome (HUS). The HUS may result in kidney damage and sometimes is fatal to those infected. The mechanism controlling SLT production is not clearly understood. We studied the effects of changing bacterial growth media on SLT production. Our results showed that addition of sugars reduced the production of SLT and indole, a chemical secreted by bacteria for cell to cell communication. However, the reduction in the production of indole was restored (but not SLT) by lowering the acidity of the media. This study provided useful information for developing means to control the pathogenicity of the toxin producing E. coli.
Technical Abstract: Human pathogenic E. coli O157:H7 produces Shiga-like toxins (SLT) that causes hemolytic uremic syndrome. Typically SLT are released when a bacterium lyses but the mechanism on controlling SLT production is not clearly understood. This paper studies the growth and cell growth and metabolism of the E. coli in Luria Bertani (LB) broth with and without added sugars. Sugars added to LB broth cause a variety of changes to pathogenic E. coli O157:H7. In plain LB media the bacteria produce indole and SLT With the addition of sugar to the broth, the cells produce significantly less of these compounds (11% indole and 33% shiga toxin in glucose LB broth). The use of LB broth conditioned by E. coli K12 growth, also reduced the growth (80% in plain LB, lactose and glucose + lactose CM, 1.5% in glucose CM) and SLT production (< 8% in all CM) of a subsequently inoculated pathogenic strain. The chemistry of these inhibitions and possible role of quorum sensing molecules are discussed.