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. 2015 Oct 20;112(44):E6028–E6037. doi: 10.1073/pnas.1515749112

Fig. 3.

Fig. 3.

Characterization of ex vivo growth of B. bacteriovorus on ghost cells. (A) Viable counts of B. bacteriovorus 109J 24 and 48 h after inoculation of ∼2 × 107 pfu/mL AP cells with ghost cells containing Hepes buffer [G(H)], ghosts containing prey extract [G(E)], ghosts mixed with prey extract [G(H)+E], ghosts mixed with PYE medium [G(H)+P], prey lysate (Lysate), or with ghost cells after vigorous vortexing [G(E) VTX]. Values are averages of three independent experiments, each performed in triplicate. Error bars indicate SD. (B) Growth and septation of B. bacteriovorus 109J (∼2 × 107 pfu/mL) incubated with ghost cells and prey extract, measured as changes in average cell area (in square micrometers) of a representative batch monitored by FISH coupled with image cytometry. Filaments reach maximal area (in square micrometers) 16 h after inoculation. Error bars indicate SE. The number of images analyzed per time point were 0 h, 7,261; 4 h, 7,774; 8 h, 7,633; 12 h, 7,269; 16 h, 8,143; 20 h, 7,047; and 24 h, 6,775. (C) Area (in square micrometers) of AP cells taken from a predation culture (AP) or after 16 h of incubation in various conditions (abbreviations are as in A). The area (in square micrometers) was monitored as in B. Sixty percent of the predatory cells elongate (values below the “Elongated” line threshold) only in the presence of ghost cells and prey extract. The number of images analyzed per treatment were AP, 6,984; lysate, 6,873; G(H), 6,739; G(H)+P, 6,938; and G(H)+E, 1,836. The population incubated with G(H)+E elongated significantly and increased its average cell area (one-way ANOVA: df = 4, F = 1,328.8, P = 0; Tukey’s HSD post hoc test: P < 10−4), compared with the other treatments in which the cell area distribution was similar to that of untreated AP cells (for more information see Fig. S4). (D) DAPI stain of filamentous ex vivo growth of B. bacteriovorus cultured for 16 h with ghost cells and prey extract. Filaments are composed of 20 ± 5.7 daughter cells (distinct nucleoids) per filament. Growth is not confined to the ghost interior.