Figure 1.
Colonization of P. aeruginosa biofilms by E. coli in R2A medium in a microfluidic flow cell.
E. coli appears red and P. aeruginosa appears green or yellow. A) E. coli deposited on 3-day old P. aeruginosa biofilm (grid unit is 23.8 µm). B) Resulting mixed E. coli – P. aeruginosa biofilm on day 6 (grid unit is 23.8 µm). C) Horizontal section near the base of the biofilm and vertical sections of the biofilm shown in panel B (scale bar = 20 µM). D) P. aeruginosa and E. coli biomass in mixed biofilms on day 6 compared with biomass of 6-day old mono-cultured P. aeruginosa biofilms.
Figure 2.
Co-development of E. coli and P. aeruginosa biofilms in a microfluidic flow cell and R2A medium.
E. coli appears red and P. aeruginosa appears green or yellow. A) 3-day old co-inoculated P. aeruginosa - E. coli biofilm (grid unit is 23.8 µm). B) Horizontal section near the base of the biofilm and vertical sections of the biofilm shown in panel A (scale bar = 20 µM). C) P. aeruginosa and E. coli biofilm biomass on day 3.
Figure 3.
Colonization of P. aeruginosa biofilms by E. coli under varying R2A medium concentrations in a microfluidic flow cell.
E. coli appears red and P. aeruginosa appears green. Column A) E. coli deposited on 3-day old mono-species P. aeruginosa biofilms under 4x and 8x R2A concentrations (grid unit is 23.8 µm). B) P. aerugiosa and E. coli biofilms on day 6, 3 days after introduction of E. coli (grid unit is 23.8 µm). C) Horizontal section near the base of the biofilm and vertical sections of the biofilm shown in panel B (scale bar = 40 µm). D) Biomass fraction vs. biofilm height graph. P. aeruginosa biofilm biomass increased with R2A concentration. E. coli dominated the community under all medium concentrations regardless of the P. aeruginosa cluster morphology. Biofilms were counter-stained by SYTO 62.
Figure 4.
E. coli colonization of pre-established P. aeruginosa biofilms under varying R2A medium concentrations.
A) Average biofilm biomass vs. R2A concentration for 1) P. aeruginosa on day 3, 2) E. coli on day 6, and 3) P. aeruginosa on day 6. B) Average P. aeruginosa cluster height vs. R2A concentration on day 3.
Figure 5.
Colonization of P. aeruginosa biofilms by E. coli under a controlled flow gradient in a planar flow cell and in R2A medium.
E. coli appears red and P. aeruginosa appears green. Results are presented for two local fluid velocities, 0.96 mm/s (top row) and 1.69 mm/s (bottom row). Column A) E. coli deposited on 3-day old P. aeruginosa biofilms (grid unit is 23.8 µm). B) Mixed P. aerugiosa and E. coli biofilms on day 6, 3 days after E. coli inoculation (grid unit in B is 23.8 µm). C) Horizontal section near the base of the biofilm and vertical sections of the biofilm shown in panel B (scale bar = 15 µm). D) Distribution of P. aerugiosa and E. coli biomass as function of height, indicating that E. coli was the dominant species throughout the biofilm. E. coli appears red and P. aeruginosa-GFP appears green.
Figure 6.
Biomass of P. aeruginosa and E. coli biofilms subjected to different local velocities in R2A medium.
A) Average biomass vs. fluid velocity for mono-cultured, 3-day old P. aeruginosa biofilms. B) Average biomass vs. fluid velocity on day 6 of experiments on colonization of P. aeruginosa by E. coli (after 3 days of mono-culture P. aeruginosa growth plus an additional 3 days after introduction of E. coli).
Figure 7.
Colonization of E. coli biofilms by P. aeruginosa in R2A medium.
E. coli appears red and P. aeruginosa-GFP appears green or yellow. A) After 3-days of mono-species growth, E. coli formed sparse biofilms composed of small, isolated cell clusters (grid unit is 23.8 µm). B) Mixed P. aeruginosa and E. coli biofilm on day 6, after 3 days of mono-species E. coli growth plus 3 additional days of multi-species growth after inoculation of P. aeruginosa. (grid unit in B is 23.8 µm). Following introduction of P. aeruginosa, E. coli grew prolifically and adopted a configuration similar to that observed in other mixed-species experiments. C) Horizontal section near the base of the biofilm and vertical sections of the biofilm shown in panel B (scale bar = 20 µm). D) Biomass of 3-day- and 6-day-old E. coli mono-cultured biofilms. E) Biomass of co-developed biofilms after 3 days of E. coli growth plus 3 additional days of multi-species growth after inoculation of P. aeruginosa.
Figure 8.
Colonization of indole-deficient E. coli JW3686 biofilms by P. aeruginosa in R2A medium.
E. coli appears red and P. aeruginosa-GFP appears green or yellow. A) Mono-cultured, 3-day old E. coli formed sparse biofilms composed of small, isolated cell clusters (grid unit is 23.8 µm). B) Mixed P. aeruginosa and E. coli biofilm on day 6, after 3 days of mono-species E. coli growth plus 3 additional days of multi-species growth after inoculation of P. aeruginosa. (grid unit in B is 23.8 µm). Following introduction of P. aeruginosa, E. coli grew extensively and adopted a configuration similar to that observed in other mixed-species experiments. C) Horizontal section near the base of the biofilm and vertical sections of the biofilm shown in panel B (scale bar = 40 µm).
Figure 9.
Biomass of E. coli JW3686 and BW25113 biofilms in mono-culture and after colonization by P. aeruginosa in R2A medium.
A) Average biomass of mono-cultured E. coli on day 3. B) Average biomass of E. coli and P. aeruginosa in mixed biofilms on day 6, 3 days after introduction of P. aeruginosa.