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Figure 1 | BMC Microbiology

Figure 1

From: Biofilms formed by Candida albicans bloodstream isolates display phenotypic and transcriptional heterogeneity that are associated with resistance and pathogenicity

Figure 1

Candida albicans clinical isolates vary in their ability to form biofilms. Forty-two C. albicans bloodstream isolates were used to evaluate biofilm formation of strains derived from a clinical setting. (A) Standardised C. albicans (1 × 106 cells/mL) in RPMI-1640 were grown in flat-bottomed 96 well microtitre plates for 24 h at 37°C. Mature biofilms were carefully washed with PBS, allowed to air dry and biomass quantified by staining with 0.05% w/v crystal violet solution. The biofilms were washed and destained with 100% ethanol. Biomass was quantified spectrophotometrically by reading absorbance at 570 nm in a microtitre plate reader (FluoStar Omega, BMG Labtech). Eight replicates were used for each isolate and was carried out on two separate occasions, with the mean of each represented. C. albicans LBF (square), HBF (triangle) and IBF (circle) were defined by the upper and lower quartiles, as shown by crystal violet stained biofilms. (B) Three C. albicans LBF and HBF were standardised (1 × 106 cells/mL) in RPMI-1640 and grown in 12 well plates for 24 h at 37°C. Biofilms were washed with PBS, biomass scraped and passed through 0.22 μm filters before the filters containing the biofilms were dried at 37°C for 24 h. Biofilm dry weight was then measured for LBF and HBF, in triplicate on three separate occasions. Data represents mean ± SD with significance **p < 0.005. (C) One C. albicans LBF (i, ii) and HBF (iii, iv) were grown on Thermanox™ coverslips for 24 h at 37°C. Biofilms were then processed and viewed on a JEOL JSM-6400 scanning electron microscope and images assembled using Photoshop software. Note the lack of biomass and hyphal cells in LBF. Scale bars represent 20 μm and 5 μm for 1000× (i, iii) and 3000× (ii, iv) magnifications, respectively.

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