TABLE 1.

Influence of reduced water availability on biofilm properties^a

Treatment and day	Microcolony surface area (μm2)b	Density (cells/100 μm2)c	% cell-free areac	Biofilm cell ht (μm)d	EPS thickness at air interface (μm)e
None
1	32,622 ± 5,234			6.2 ± 0.3	1.5 ± 0.1
2		114.8 ± 0.8	22.2 ± 0.4	6.3 ± 0.3	1.9 ± 0.5
4	40,801 ± 2,457			6.1 ± 0.3	1.6 ± 0.1
−1.5-MPa water potential, NaCl
1	23,899 ± 3,821			6.7 ± 0.2	2.0 ± 0.3
2		72.3 ± 0.9	24.6 ± 0.3	6.3 ± 0.2	1.9 ± 0.3
4	38,568 ± 2,457			6.8 ± 0.9	1.9 ± 0.1
−1.5-MPa water potential, PEG 8000
1	1,568 ± 405			11.0 ± 0.8	2.7 ± 0.5
2		71.8 ± 1.6	49.7 ± 1.1	12.3 ± 0.4	3.5 ± 0.2
4	4,900 ± 1,056			14.4 ± 0.9	3.9 ± 0.5

^aData are expressed as means ± standard errors of the means.

^bMicrocolony area at the substratum surface. Values were derived from the average microcolony surface area per field of view (number of samples, 3 to 4) containing 1 to 14 microcolonies.

^cThe proportion of a 100-μm² area devoid of cells. Values were derived from 29 to 39 x-y plane CSLM images from 8 to 13 randomly chosen microcolonies obtained in two separate experiments.

^dThe height from the substratum to the top of biofilm. Values were derived from nine random height measurements of three to eight x-y projections of a stacked series of x-y plane CSLM images.

^eThe thickness of the calcofluor-stained layer from the top of the biofilm to the air interface. Values were derived from the images used for the biofilm cell height measurements.