Figure 3.

ppGpp accumulation in strain US6-1, ∆rsh and ∆rsh (pCM62-rsh) in different growth phases. Levels of ppGpp in cultures of US6-1 (a,d), ∆rsh (b,e) and ∆rsh (pCM62-rsh) (c,f) in the exponential growth phase (36 h) and in the stationary phase (72 h) were monitored by reverse phase high-performance liquid chromatography (HPLC) analysis. The eluted nucleotides were monitored at 254 nm and identified by comparison with the retention time of 100 µM ppGpp standard. ppGpp standard was eluted at 71 min under the current conditions and the position is indicated by an arrow.