Figure 4

In silico model simulations of the choline - betaine pathway of the osmoadaptation mechanism. In C. salexigens, the osmoprotectant betaine is synthesized from its precursor choline in two steps. Whereas the first step from choline to betaine aldehyde is catalyzed either by membrane-bound choline dehydrogenase (EC 1.1.99.1, CsaI1514) or by a ferredoxin-dependent choline monooxygenase (EC 1.14.15.7, CsaI2455), betaine aldehyde dehydrogenase (EC 1.2.1.8, CsaI1515) is involved in the second, betaine aldehyde to betaine step. FBA simulations were performed with biomass as the objective function and 3 mmol/gDW/h glucose uptake rate and the computed metabolic flux values in mmol/gDW/h are shown on bar charts. Uptake of exogeneous choline was restricted to 0, 1.0, 1.2, 1.4, 1.6, 1.8 and 2 mmol/gDW/h.