Effects of ethanol on biofilm formation and carbohydrate production.

<p>Biofilms formed by <i>A. baumannii</i> ATCC 17978 cells cultured in LB supplemented with 0%, 1% or 2% ethanol were visualized by crystal violet staining (A) and further quantified by colorimetry, after elution of the retained stain, in relation to the total biomass of each tested sample (B). A tube incubated with sterile medium (SM) was used as a negative control. (C) Carbohydrate content of biofilms formed on plastic by <i>A. baumannii</i> ATCC 17978 cells statically cultured in LB broth containing 0%, 1% or 2% ethanol determined with the L-cysteine monomeric carbohydrate assay. The carbohydrate concentration of biofilms was normalized to the protein content of each analyzed sample. Error bars shown in panels B and C represent 1 standard error. (D) Scanning electron microscopy of biofilms formed on plastic above, at and below the meniscus of LB broth static cultures containing 0%, 1% or 2% ethanol incubated overnight statically at 37°C. All micrographs were taken at a X25,000 magnification. The bar shown in the left bottom panel represents 1 µm.