Attachment on glass (A) and polystyrene plates (B-C). (A) Ring formation at the glass-air-liquid interface after bacterial static growth. From left to right ANU843 (wild-type strain) and its derivatives ANU843ΔC2 (ΔC2), ANU843C2+ (C2+), ANU843ΔC2 complemented (ΔC2comp), and ANU843emptyvector (EV). Note the formation of a thick visible ring in ΔC2. (B-C) The data show absorbance values of CV-stained biofilms following growth in minimal media and TY at different times after inoculation. The culture media of the static culture was removed and differences in biofilm matrix development were measured by the intensity of CV staining. Before CV staining, the OD600 of the broth cultures were measured in a Microtiter Plate reader to verify that no differences in growth rate among the wells had occurred. Each datum point is the average of at least 20 wells. Error bars indicate the standard deviation. Each experiment was repeated at least three times. Values followed by the same letter do not differ significantly according to Fisher protected LSD test at P = 0.01. The degree of biofilm formation was significantly different among the strains tested, although these differences were less pronounced in the complex medium.