Figure 4.

Quantification of Fth’ survival in natural ex vivo biofilm. The number of colony forming units (CFU) of Fth and the genome equivalents (GE) were measured over time of the representative experiment conducted in November of the year. (A) Comparison of survival of planktonic Fth and Fth in the biofilm at room temperature and at 4°C; (B) Long term survival of planktonic Fth and Fth in the biofilm in natural water at 4°C; (C) The same experiment as shown in (B), but detection of Fth DNA in biofilm, in planktonic supernatant from the biofilm, and in natural water without previous biofilm formation (control). The Thermanox™ coverslips overgrown with or without biofilm in NSW were infected with 4×10⁷ F. tularensis on day 0. At several time points as indicated, CFU and GE were determined from the NSW or the supernatant of the coverslips, and of the scraped biofilm (see Material and Methods).