FIGURE 6.

Interbacterial curli formation between E. coli and S. typhimurium curli mutants restored bacteria adherence to agar surface. A, overnight cultures of E. coli, S. typhimurium, or a 1:1 (A₆₀₀/A₆₀₀) mixture of E. coli and S. typhimurium curli mutants were spread on YESCA agar in 12-well tissue culture plates, then incubated at 26 °C for 3 days. Bacterial adhesiveness was determined by the percentage of adhered bacteria after vigorous washing as described under ”Experimental Procedures.“ B, overnight cultures of E. coli constitutively expressing YFP from plasmid pAH16, S. typhimurium expressing constitutively expressing mCherry from pAH9 (60), or the mixed culture of E. coli/pAH16 and S. typhimurium/pAH9 were spread on YESCA agar on 12-well tissue culture plates, incubated at 26 °C for 3 days, and washed in PBS with vigorous shaking. Percentage of adhesive S. typhimurium was determined by mCherry signal with the excitation wavelength at 600 ± 9 nm and the emission wavelength at 630 ± 20 nm.