The role of glycolytic substrates in the initiation and maintenance phases of colonization of the mouse large intestine by Escherichia coli MG1655 and Escherichia coli EDL933
Escherichia coli is a gram-negative motile rod, and is one of the most common bacterial strains isolated from the human intestinal tract (1,2). E. coli K-12, strain MG1655, is a non-pathogenic laboratory strain of E. coli whose genome has been fully sequenced (1). E. coli O157:H7, strain EDL933, a shigatoxin-producing E. coli (STEC), is a human pathogen, whose genome has also been fully sequenced (34). E. coli EDL933 was first isolated in August of 1982 from patients in the United States suffering from an outbreak of bloody diarrhea, which was traced to contaminated hamburgers (8,9,10,11). E. coli O157:H7 infections are transmitted via the fecal-oral route (8,9,11,16,17), with an infectious dose believed to be similar to that of Shigella (13). Genetically, E. coli EDL933 and E. coli K-12 are highly divergent (34). These genetic differences may play a role in the ability of both strains to initiate, grow, and maintain co-colonization in the mouse large intestine, in the presence of one another. The streptomycin-treated mouse model was used to determine the colonization abilities of both strains (66,132). Molecular techniques were utilized to make gene deletions in E. coli EDL933 to determine which glycolytic substrates may play a key role in the ability of low numbers of E. coli EDL933 to initiate, grow, and maintain colonization of the mouse large intestine in the presence of high numbers of E. coli MG 1655. Colonization experiments showed that utilization of ribose is required for E. coli EDL933 to maintain colonization, but not necessary for E. coli MG1655. Fucose is a required nutrient for E. coli EDL933 during maintenance of colonization, and is a preferred nutrient source for E. coli MG1655 during maintenance. It appears that gluconate is a preferred nutrient for E. coli MG1655 during maintenance of colonization, but is not necessary for colonization of E. coli EDL933. Overall, this study suggests that the utilization of glycolytic substrates is important in the maintenance phase of colonization by E. coli strains. However, the gene or genes involved in the initiation of colonization, as well as growth in the mouse large intestine, are not as easily defined. ^
Regina L Miranda,
"The role of glycolytic substrates in the initiation and maintenance phases of colonization of the mouse large intestine by Escherichia coli MG1655 and Escherichia coli EDL933"
Dissertations and Master's Theses (Campus Access).