FIG 7.

H. baltica holdfasts tolerate higher ionic strength than C. crescentus holdfasts. (A) Images of WGA-AF488-labeled H. baltica ΔhfaB and C. crescentus ΔhfaB shed holdfasts bound to glass slides and incubated in different concentration of NaCl for 4 h. (B) Percentages of holdfasts bound per field of view at different concentrations of NaCl. The number of holdfasts bound per field of view at 0 M NaCl was standardized to 100%. The arrow indicates the ionic strength of marine broth and the Baltic Sea (250 mM), from which H. baltica was isolated. The data are expressed as averages from 6 independent replicates, and the error bars represent the standard errors. (C) Percentages of holdfasts bound per field of view at different concentrations of MgSO₄. The number of holdfasts bound per field of view at 0 M MgSO₄ was standardized to 100%. The data are expressed as averages from 4 independent replicates, and the error bars represent the standard errors. (D) Images of WGA-AF488-labeled holdfasts already bound to a glass surface and incubated in 0 mM NaCl and 1 M NaCl for 12 h. (E) Percentages of holdfasts bound per field of view at 0 M or 1 M NaCl. The first incubation was done by adding 0 M or 1 M NaCl to a holdfast suspension spotted on a glass slide. After a 12 h of incubation, the second incubation was done, after washing off unbound holdfasts, by adding 0 M or 1 M NaCl directly to the holdfasts attached to the glass slide and incubating them for another 12 h. The number of holdfasts bound per field of view at 0 M NaCl was standardized to 100%. The data are expressed as averages from 5 independent replicates, and the error bars represent the standard errors.