Figure 2.

Simplified representation of exponential and post-exponential phase-dependent utilization of serine, glucose and glycerol by L. pneumophila. In vitro isotopologue labeling experiments using ¹³C-serine, ¹³C-glucose and ¹³C-glycerol revealed a bipartite metabolism in which serine (in red) is mainly used during the exponential phase of growth and enters primarily the TCA cycle, whereas glucose (in blue) and glycerol (in green) are shuffled into anabolic processes during the post-exponential growth phase of L. pneumophila. Relative carbon fluxes are depicted by the thickness of the arrows. For more detail, see the text. ED, Entner–Doudoroff pathway; PPP, pentose phosphate pathway; EMP, Embden-Meyerhof-Parnas pathway (glycolysis); TCA, tricarboxylic acid cycle (adapted from Eisenreich and Heuner, 2016).