Article Figures & Data
Figures
- FIG. 1.
Effects of glucose on biofilm formation by E. coli K-12 strains and their csrA mutants (A) and by enteric pathogens (B) in CFA medium. The K-12 parent strains were MG1655 (MG), MC4100 (MC), and W3110 (W). Clinical strains were E. coli P18 (E.c.), C. freundii P5 (Citro), K. pneumoniae P30 (Kleb), E. coli O157:H7 EF302 (O157), and S. enterica Typhimurium ATCC 14028 (S.t.). Biofilm was determined after 24 h of growth at 26°C in the presence or absence of 0.2% glucose. Each bar shows the average and standard error of three separate experiments (P < 0.0001). ∗, significant difference with respect to cultures lacking glucose. Essentially identical effects of glucose were observed in LB medium (not shown).
- FIG. 2.
Growth curves of MG1655, its isogenic csrA mutant, TRMG1655, and their crp and cya derivatives. Cultures were grown at 26°C in LB medium containing 0.2% glucose (A) or CFA medium (B) and sampled at the indicated times, and growth was determined (A600).
- FIG. 3.
Effects of crp on specific biofilm formation by MG1655 and its isogenic csrA mutant TRMG1655. Cultures of crp wild type or isogenic mutant strains were grown for 24 h in CFA medium, and biofilm was determined after 24 h at 26°C. Each bar shows the average and standard error of three experiments (P < 0.0001). ∗, significant difference between the crp mutant and its parent strain. Results were essentially identical in LB medium containing 0.2% glucose (not shown)
- FIG. 4.
Effects of cya and exogenous cAMP on specific biofilm formation by MG1655 and its csrA mutant TRMG1655. Cultures were grown for 24 h in LB medium plus 0.2% glucose or CFA medium in the presence of 0, 2, or 5 mM cAMP. Each bar shows the average and standard error of three experiments. ∗, that cya disruption significantly decreased biofilm formation (P < 0.0001); ∗∗, addition of cAMP to the culture resulted in a significant increase in biofilm (P < 0.0001).
- FIG. 5.
Temporal effects of glucose on biofilm formation at 24 or 48 h of growth. Glucose (0.2% [wt/vol], final concentration) was added at the indicated times after inoculation of MG1655 or its csrA mutant, TRMG1655, into CFA or LB medium. Crystal violet staining was measured at A630 at either 24 or 48 h of growth, and results were calculated as percentages of values for the control cultures that lacked glucose. Each point is the average and standard error of three separate experiments. ∗ and ∗∗, significant decrease or increase (P < 0.0001), respectively, in biofilm formation relative to controls lacking glucose.
Tables
- TABLE 1.
Bacterial strains or phage used in this study
Strain or phage Relevant genotype or description Reference or source E. coli K-12 strains MG1655 F− λ− Michael Cashel CAG18642 zhf-331::Tn10; 57.5 min 30 MC4100 F Δ(argF-lac)U169 rpsL relA flhD deoC ptsF rbsR 11 ML2a met gal hsdK R supE supF Δcya::Kanr 10 SA2777a F rpsL relA Δcrp::cam S. Garges and S. Adhya W3110 F− λ−mcrA mcrB IN(rrnD-rrnE)1 Richard E. Wolf, Jr. TR1-5BW3414a csrA::Kanr 25 Clinical strains P5 C. freundii 14 P18 E. coli 14 P30 K. pneumoniae 14 EF302 E. coli O157:H7 16 ATCC 14028 S. enterica serovar Typhi- urium 2 Bacteriophage P1vir Strictly lytic P1; forms clear plaques 30 ↵ a Mutant alleles Δcya::kanR, Δcrp::cam, and csrA::kanR were moved among strains by P1vir transduction or cotransduction. The strain prefix TR indicates the presence of the csrA::Kanr allele.
