Table 1 Frequency of structures observed by frames in biofilms of P. mirabilis strains formed on chitin between 24 and 96 h. S, number of frames with structure observed; F, number of frames. The non-parametric Mann–Whitney test for two independents samples indicated significant differences for pillars and channels *p < 0.05

From: Environmental scanning electron microscopy analysis of Proteus mirabilis biofilms grown on chitin and stainless steel