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Fig. 5 | BMC Microbiology

Fig. 5

From: Disruption of rcsB by a duplicated sequence in a curli-producing Escherichia coli O157:H7 results in differential gene expression in relation to biofilm formation, stress responses and metabolism

Fig. 5

Determination of the ability of the rcsB gene of the CR parental strain (NADC 6564) for complementing the CR+ isolate (NADC 6565) for the phenotypes putatively altered due to the loss of the RcsB function. a The overnight cultures of the CR parental strain carrying the empty vector pCRXL and the CR+ mutant strain complemented with plasmid pSM757 (pCRXL carrying a cloned copy of the rcsDB operon), pSM759 (pCRXL carrying a cloned copy of the rcsB gene), or pCRXL were grown at 28 °C in LB-No Salt broth. Aliquots (5-μl) of these cultures were spot-inoculated on Congo red-containing agar plates. After 48 h of incubation at 28 °C, the color (white or red) of the growth produced at the spots of inoculation was photographed. b The overnight cultures of the CR parental strain carrying pCRXL and the CR+ mutant strain complemented with plasmid pSM757, pSM759 or pCRXL were grown at 37 °C in LB broth and 2-μl aliquots of these cultures were spot-inoculated on soft-motility agar plates. After incubation at 28 °C or 37 °C for appropriate length of time, the motility zones (visible as white-colored rings at the spot of inoculation) produced on these plates were captured by photographing. c The CR parental strain carrying the pCRXL vector and the CR+ mutant strain complemented with plasmid pSM757 (pCRXL carrying a cloned copy of the rcsDB operon), pSM759 (pCRXL carrying a cloned copy of the rcsB gene), or pCRXL were grown (LB-No Salt, pH 5.5) overnight at 28 °C. These cultures were diluted 1:1000 in LB No Salt (pH 2.5) and incubated at 28 °C or 37 °C. Aliquots (100 μl) were withdrawn from these cultures at 0, 2, 4 and 6 h intervals and 10-fold serial dilutions of these cultures were plated on LB-agar plates containing kanamycin. After incubation at 37 °C, the numbers of colonies produced on these plates were counted (CFU/ml) and plotted against time (h) on a XY graph. Each time point represents means of three independent assays and error bars represent standard deviation of 2

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