Demonstration of exopolysaccharide production by enterohemorrhagicEscherichia coli

Abstract

Enterohemorrhagic Escherichia coli O157:H7 produces visibly slimy colonies when grown on Sorbitol/MacConkey or Maloney's agar plates at room temperature, indicative of exopolysaccharide (EPS) production. Eighteen of 27 (67%) wild-type E. coli O157:H7 isolates produced enough EPS to be visually distinguishable. Of five strains that showed no visible EPS production on these media, four (80%) did produce slimy colonies on media containing higher salt concentrations. Measurements of EPS production by colorimetric determination of uronic acid indicated that EPS production was affected by growth temperature, atmosphere, and medium. Wild-type E. coli O157:H7 strain 932 produced the greatest amounts of EPS when grown anaerobically at 37 degrees C, whereas its plasmid-cured derivative 932P produced large quantities of EPS when grown aerobically at room temperature. Electron micrographs revealed thin, flexible fibers extending from the bacterial cell surface. Cells of strain 932P grown aerobically at room temperature were completely encased in a thick EPS matrix. Chemical analysis of purified EPS revealed that it is very similar or identical to colanic acid. E. coli O157:H7 adheres better to INT 407 cells when grown under conditions that favor high EPS production than when grown under conditions that repress EPS production.

Positive control of the two‐component RcsC/B signal transduction network by DjlA: a member of the DnaJ family of molecular chaperones in Escherichia coli

“…Enteropathogenic strains of E. coli have been shown to be capable of elucidating mucoid capsule (Junkins and Doyle, 1992), although colanic acid capsule plays no apparent role in evasion from phagocytosis or resistance to complement-mediated killing (Allen et al, 1987). A thorough understanding of the mechanism of activation of the rcs signalling pathway would resolve the mystery of why E. coli possesses such a tightly regulated adaptive response.…”

Exopolysaccharide Sugars Contribute to Biofilm Formation bySalmonella entericaSerovar Typhimurium on HEp-2 Cells and Chicken Intestinal Epithelium

“…The EPS matrices from different bacteria are composed of polysaccharides, including alginate in Pseudomonas aeruginosa when forming biofilm in cystic fibrosis patients (11), cellulose in Salmonella enterica serovar Enteritidis (30), and colanic acid in Escherichia coli (9). It has been suggested that most bacteria can produce EPS in specific environmental conditions, but production is typically lost by culture on bacteriological media in a laboratory setting (19). Thus, while bacterial species have genes that determine the amount and composition of the EPS produced, environmental surfaces and conditions are also important factors in EPS production and play a role where specific bacterial species can form biofilms (4,5).…”

Gordonia polyisoprenivorans from groundwater contaminated with landfill leachate in a subtropical area: characterization of the isolate and exopolysaccharide production

“…The ability of strains of G. polyisoprenivorans to produce smooth and rough variants was previously noted in strains VH2 (2,23) and Y2K (2). Fusconi and Godinho (14) selected this strain for EPS production studies on the basis of the mucoid aspect of colonies on solid media and the mucoid mode of growth in liquid media, characteristics that indicate production of large amounts of EPS by bacterial strains (8,18). Experimental measurement of EPS produced by Lc strain during growth on one out of the two carbon sources confirmed predictions of EPS production by the strain.…”