08 E-05 8.1 E-15 Small subunit 3 15 39 0.08 4.68 E-13 Tricarboxylic acid cycle 6 2 20 1.75 E-05 0.11 Amino acid biosynthesis

3 13       Glutamate 0 4 13 – 6.2 E-04 Leucine 0 2 5   9 E-03 Other 3 7 – - – ATP synthesis 6 9 20 1.75 E-05 4.9 E-09 Respiratory chain 8 11 26 5.36 E-07 2.02 E-10 Stress response 4 5 – - – 1Number of genes in the annotated database Figure 9 Common differentially regulated genes in 1 h and 3 h biofilm to batch comparison and C. albicans cells growing under hypoxic condition. Loss of strong adhesion is not influenced by oxygen Selleck GF120918 availability at the interface or in the medium The porous structure of silicone elastomers results in a high gas permeability [40]. (Silicone elastomer is 25 times as permeable p38 MAPK inhibitors clinical trials to oxygen as natural rubber). Thus it is likely that oxygen penetration at the tubing surface might establish a gradient of oxygen at the biofilm/surface interface. The timing of the structural

transition in which hyphae extending from the edges of the biofilm were first observed corresponds with the loss of adhesion (Figure 3) suggesting that the two phenomena might be related. We tested the hypothesis that availability of oxygen at the biofilm/surface interface was providing a stimulus to induce detachment by placing a gas tight glass sleeve around the biofilm reactor and filling the sleeve with nitrogen gas. Nitrogen was induced after 40 min of growth to allow time for the biofilm to establish firm adhesion to the surface. The presence of the nitrogen had a measurable effect on hyphal length which was reduced by 62% compared to the standard conditions (29 μm versus 47 μm, p value 1.4 e-6). However, there was no visible difference in the detachment phenotype

at 3 h. We performed additional experiments to see if we could perturb the detachment Fludarabine in vitro phenotype by availability of oxygen by either filling the glass sleeve with pure oxygen or saturating the medium with pure oxygen during biofilm development. Although these there were subtle perturbations in the biofilm structure (data not shown) the detachment phenotype was not appreciably altered. Mutant strain analysis suggests that transcriptional regulation of a single gene candidate is not responsible for mediating the loss of strong adhesion Based on the array analysis presented above we chose seven genes (AMS1, PSA2, CWH8, PGA13, orf19.822, AQY1, and ALS1) for further analysis. (A cwh8/cwh8 mutant could not be produced since it formed a trisomic suggesting that it is a lethal mutation). In addition to genes indicated by our array analysis, we chose two genes for further study based on their possible function in the detachment process as suggested by previous work (YWP1 and MKC1) [16, 41].