Characterization of biofilm-like structures formed by Pseudomonas aeruginosa in a synthetic mucus medium

BMC Microbiology

Table 1 Effect of time and environmental variables on PAO1/pMRP9-1 BLS

Variable	Image stacks (#)^a	Total biovolume (μm³/μm²)^b	Mean thickness (μm)^c	Roughness coefficient^d	Total surface area × 10⁷ (μm²)^e	Surface to volume ratio (μm²/μm³)^f
Time (under 20% EO ₂ )
48 h	10	6.52 ± 0.43	11.6 ± 0.28	0.53 ± 0.02	1.65 ± 0.24	1.54 ± 0.10
72 h	10	11.1 ± 0.40	15.5 ± 0.23	0.18 ± 0.02	2.15 ± 0.03	1.01 ± 0.04
6 d	10	18.2 ± 0.32	17.8 ± 0.06	0.02 ± 0.00	0.96 ± 0.12	0.28 ± 0.04
Mucin concentration (3 d under 20% EO ₂ )
1X	10	11.1 ± 0.40	15.5 ± 0.23	0.18 ± 0.02	2.15 ± 0.03	1.01 ± 0.04
0.5X	10	13.5 ± 0.24	17.0 ± 0.05	0.08 ± 0.00	2.44 ± .045	0.94 ± 0.03
2X	10	15.4 ± 0.35	17.3 ± 0.08	0.06 ± 0.00	1.97 ± .098	0.67 ± 0.05
DNA concentration (3 d under 20% EO ₂ )
1X	10	11.1 ± 0.40	15.5 ± 0.23	0.18 ± 0.02	2.15 ± 0.03	1.01 ± 0.04
0.5X	10	2.42 ± 0.54	4.37 ± 1.37	1.33 ± 0.20	0.76 ± .220	1.55 ± 0.15
1.5X	10	2.48 ± 0.22	5.52 ± 0.64	1.07 ± 0.07	0.96 ± .086	2.02 ± 0.01
Oxygen concentration (EO ₂ ) ^g
20%	10	11.1 ± 0.40	15.5 ± 0.23	0.18 ± 0.02	2.15 ± 0.03	1.01 ± 0.04
10%	10	19.4 ± 0.28	17.9 ± 0.04	0.01 ± 0.00	0.46 ± 0.12	0.13 ± 0.03
0%	10	0.28 ± 0.19	0.41 ± 0.27	1.94 ± 0.04	0.07 ± 0.06	1.75 ± 0.30

^a Each experiment was done in duplicate. Two 10-image stacks were obtained from random positions within the BLs. A total of 40-image stacks were analyzed were analyzed using the COMSTAT program [20]. Values represent the mean ± SEM.
^bEstimates the biomass of the BLS.
^cMeasures spatial size of the BLS.
^dAssessment of the variation in the thickness of the BLS, or BLS heterogeneity.
^eTotal of the area occupied in each image stack.
^fEstimates the portion of the biofilm exposed to nutrients; biovolume divided by the surface area of the substratum.
^g20%, aerobic; 10%, microaerobic; 0%, anaerobic; cultures were grown for 3 d, except 0% EO₂ for 6d.

ISSN: 1471-2180