Curli expression of enterotoxigenicEscherichia coli

Abstract

One hundred and four enterotoxin producing Escherichia coli strains of wide geographical origin were tested for the expression of curli fimbriae by transmission electronmicroscopy and by ELISA using curli-specific antibodies, as well as for the presence of curli-specific gene sequences by PCR. All isolates, irrespective of the production of the fimbriae, carried sequences specific for the structure (csgA) and for one of the regulator genes (crl) of curli expression, respectively. Curli fimbriae were detected in 56 strains (53.8 %). Thirty-six strains expressed curli only when growing at 30 degrees C, 4 isolates were weakly curliated at 37 degrees C only, while on 16 strains curli was observed at both temperatures. On isolates carrying curli at both temperatures the expression of the fimbria was significantly stronger at 30 degrees C than at 37 degrees C. Curli proficiency significantly, but not completely, correlated with the binding of the Congo Red dye. The expression of curli did not confer epithelial cell invasiveness to ETEC strains but, once expressed at 30 degrees C, it facilitated the adherence of the bacteria to plastic surfaces. Curli present in more than half of the ETEC strains and expressed preferentially at low temperatures could be a factor facilitating the environmental survival of this food- and water-borne pathogen.

Community behavior and amyloid-associated phenotypes among a panel of uropathogenic E. coli

“…However, curli-independent variability in the CR phenotype among strains has been noted [35], attributed to factors such as the ability of CR to bind to cellulose[34], and should not be the only assay used to score bacterial amyloid production. Photographs of a representative set of nine isolates illustrate the range of variations in colony morphology and dye binding exhibited by the isolates.…”

Biofilm formation on the surface of polylactide during its biodegradation in different environments

“…Szabo et al [34] noted that adhesion of Escherichia coli to plastic surfaces is better at 30 • C than at 37 • C. Temperature may affect the formation of cellular structures, and these in turn may increase cell bonding to abiotic surfaces. A temperature of 20 • C facilitates the formation of fimbriae in A. veronii [35,36].…”

RcsB Contributes to the Distinct Stress Fitness among Escherichia coli O157:H7 Curli Variants of the 1993 Hamburger-Associated Outbreak Strains

“…Importantly, these transcriptional regulators interact with each other and modulate their own expression levels, resulting in a complex regulation network that fine-tunes curli biogenesis in response to various environmental and physiological signals (43,44). Natural variation in curli expression has been reported for E. coli strains isolated from diverse environments (46,61). Increased curli production has been linked to mutations in the ompR gene (68) or the csgD promoter (54,64).…”