00 px W x 600 px H; bars, 100 px. S. aureus develops BLS under 20% EO2 but not 10% EO2 S. aureus is one of the first microorganisms

that colonize and grow within the thick mucus in the lung alveoli of CF patients [8]. Thus, we determined whether S. aureus would develop BLS in ASM+ under selleck kinase inhibitor 20% or 10% EO2. The S. aureus strain AH133 which carries the GFP plasmid pCM11, was grown for 3 d at 37°C. Under 20% EO2, AH133 produced a well developed BLS within the entire gelatinous mass (Figure 9). However, under 10% EO2, the structures were far less developed with individual cells/small microcolonies scattered within the gelatinous mass (Figure 9). Compared to BLS produced under 20% EO2, total biovolume, mean thickness, and surface area of BLS produced under 10% EO2 were significantly reduced (P < 0.0001 for each value) (Table 5). In contrast, the roughness coefficient

and surface to biovolume ratio values were significantly increased (P < 0.0001 for each value) (Table 5). This suggests that unlike P. aeruginosa, S. aureus produces more developed BLS under 20% EO2 rather than under 10% EO2. Figure 9 Growth under 10% EO 2 reduces S. aureus AH133 BLS development. S. aureus strain AH133 was grown in ASM+ under 20% EO2 or 10% EO2 without shaking for 3 d. The BLS were analyzed as described in Figure 3. (A) Representative micrographs of the BLS; magnification, 10X; bar, 200.00 nm. (B) KPT-330 supplier Respective 3-D images constructed from the CLSM micrographs. Boxes, 800.00 px W x 600 px H; bars, 100 px. Table 5 Effect of oxygen on Staphylococcus aureus AH133 BLS a EO2 Image stacks (#) b Total biovolume (μm3/μm2) b Mean thickness (μm) b Roughness coefficient b Total surface area × 107(μm2) b Surface to volume ratio (μm2/μm3) b 20% 9 7.00 ± 0.46 7.57 ± 0.50 0.58 ± 0.17 0.76 ± 0.12 0.57 ± 0.09 10% 9 0.22 ± 0.03 0.27 ± 0.04 1.90 ± 0.02 0.07 ± 0.00 1.59 ± 0.01 a Strains were grown for 3 d without shaking. b See Table 1 for description of parameters.

DNA ligase P. aeruginosa eliminates BLS established by S. aureus within ASM+ The lungs of CF patients are colonized with a variety of pathogens, including S. aureus, P. aeruginosa, and K. pneumoniae, over the course of time [1]. However, as the disease progresses, the predominate pathogen within the CF infected lung is P. aeruginosa[1, 8]. Previous studies showed that QS-controlled extracellular factors produced by P. aeruginosa, including quinoline molecules and LasA, inhibited the planktonic growth of S. aureus and S. epidermidis[31, 32]. Additionally, recent studies showed that the P. aeruginosa extracellular polysaccharide as well as the organic compound cis-2-decenoic acid disrupted established biofilms produced by Gram-positive bacteria [33]. Therefore, we first determined if PAO1 inhibits the growth of the S. aureus strain AH133 in ASM+. We co-inoculated ASM+ with approximately 1 x 107 CFU/ml each of PAO1 and AH133 and incubated the culture for 48 h at 37°C under 20% EO2.