Fig. 4

Biofilm formation by Moraxella spp. isolates. Biofilm formation under static and shaking conditions in microtiter plates for Moraxella spp. nasal strains. Biofilm was measured at 24 h (open circles) and 48 h (black squares) by staining with crystal violet. In slow growers (cluster of putative new Moraxella species GM5–5, GM5–7, VL1–4, VL1–5, VL2–5, VL3–9, VL6–6) incubations were 48 h and 72 h (open circles and black squares, respectively). Quantification of biofilm was determined the absorbance at 590 nm of the dissolved dye. Strains UK1–20 and VL6–6 after 27 in vitro culture passages (UK1–20p27 and VL6–6p27) were included in the assay. Blank wells with uninoculated medium were also processed and included in the figure. Vertical dashed lines indicate the levels used in this study to consider that a strain had ability to form biofilm (Abs590 ≥ 0.6) or strong biofilm (Abs590 > 1.5)