Fig. 4
ObgGC is essential for GC viability. a The FA1090 conditional obg knockout strain, P lac ::obg GC , failed to grow when plated from freezer stocks onto GCB without (−) 100 μM IPTG, whereas abundant growth was observed on media supplemented with the inducer (+). b, c FA1090 cells carrying chromosomal P lac ::obg GC were collected from GCB agar plates supplemented with 100 uM IPTG, washed, divided, and grown in GCBL in the presence or absence of IPTG for 3 h. At this experimental time point (indicated by the blue arrow), the bacteria were harvested, washed again and growth was continued for 6 h in liquid media with (+) or without (−) IPTG, as indicated. Culture density was measured as Optical Density at OD600 (b). Cell viability was monitored every hour after the second inoculation by spotting serial dilutions onto GCB with IPTG (c). Experiments were performed in biological triplicates and means and SEM are presented. d Representative immunoblot showing ObgGC levels over time in FA1090 P lac ::obg GC grown in the presence (+) and absence (−) of IPTG. The samples were collected every hour after back dilution (as indicated), matched by the same OD600 units, and whole cell lysates were probed with anti-ObgGC antisera. e Cultures of FA1090 P lac ::obg GC grown in the liquid media in presence (+) and absence (−) of IPTG were serially diluted and spotted on GCB with (+) and without (−) the inducer. The 2- and 4-h time points from back dilution are shown