Fig 5.

A premature cellulose production that has taken place as a consequence of high intracellular c-di-GMP levels in the cell is responsible for motility inhibition. (A) Endoglucanase activity of BcsZ was confirmed by assessing carboxymethylcellulose (CMC)-degrading activity of the wild-type S. Enteritidis strain harboring the bcsZ-overexpressing plasmid pUA1108::bcsZ. As a control, the endoglucanase phenotype of the wild-type strain harboring an empty pUA1108 overexpression vector is also presented. (B) Degradation of the cellulose produced by a strain that overexpresses a unique and very active source of c-di-GMP and lacks YcgR is enough to recuperate swimming motility. Strains assayed were transformed with an empty pUA1108 plasmid or with the overexpressing plasmid pUA1108::bcsZ. Representative swimming motility plates and quantitative measurement of motility after incubation at 23°C for 16 h are shown. (C) Correlation between swimming motility, rotation behavior in the tethering assay, and cellulose production. Early cellulose synthesis was detected in strains that overexpressed a DGC and were grown under tethering assay conditions, that is, at 28°C for 6 h. Detection of cellulose production by calcofluor staining (CF) is shown in the right panel. Membrane staining with FM4-64 is shown in the intermediate panel.