The conserved carbon transfer of the underlying reactions yields a specific labelling pattern for oxaloacetate formed by each pathway which is presented in this figure. White circles represent 12C whereas black circles indicate labelled 13C. The numbers given reflect the position of

the carbon atom within the molecule. AcCoA: acetyl-Coenzyme A; EDP: Entner-Doudoroff pathway; OAA: oxaloacetate; PYR: pyruvate; TCA: tricarboxylic acid. Conclusion Being one of the first metabolic studies of members of the Roseobacter clade using the 13C labelling experimental approach, a deeper insight into the activity of the important metabolic routes of D. shibae and P. gallaeciensis was achieved. Interestingly, the use of intracellular pathways is highly similar in the studied species D. shibae and check details P. gallaeciensis. This stands in surprising contrast to the overall differences in phenotypic behaviour exhibited by these two strains, since D. shibae is an algal-associated microorganism whereas P. gallaeciensis is free-living in marine habitats. However, this may be a first indication of more general key properties among members of the Roseobacter clade that explain their enormous success in the marine realm. Methods Strains, medium and growth conditions The strains used in this study are the genome sequenced

strains Dinoroseobacter shibae DFL12 [1] and Phaeobacter gallaeciensis DSM 17395 [14]. For cultivation of both strains a defined, synthetic seawater medium (minimal medium) was used [25], containing

the following find more components per litre of medium: 4.0 g NaSO4, 0.2 g KH2PO4, 0.25 g NH4Cl, 20.0 g NaCl, 3.0 g MgCl2·6 H2O, 0.5 g KCl and 0.15 g CaCl2·2 H2O, 0.19 g NaHCO3, 1 ml trace element solution and 10 ml vitamin solution. The final glucose concentration in the medium was in the range of 0.4 to 0.9 g l-1. The trace element solution contained 2.1 g Fe(SO4)·7 H2O, 13 ml 25% (v/v) HCl, 5.2 g Na2EDTA·2 H2O, 30 mg H3BO3, 0.1 g MnCl2·4 H2O, 0.19 g CoCl2·6 H2O, 2 mg CuCl2·2 H2O, 0.144 g ZnSO4·7 H2O and 36 mg Na2MoO4·2 Y-27632 2HCl H2O per litre. The vitamin solution for D. shibae contained the following components per litre: 0.2 g biotin, 2.0 g nicotinic acid and 0.8 g 4-aminobenzoic acid. All solutions were sterilised separately and mixed at room Captisol cell line temperature prior to inoculation. For carbon labelling experiments 99% [1-13C] glucose (Euriso-Top, Saint-Aubin, France) was used as substrate. The cultivations were carried out on orbital shakers at 200 rpm in 500 ml shaken flasks with a culture volume of 50 ml at 37°C (D. shibae) and 28°C (P. gallaeciensis). To ensure comparable conditions between the two microorganisms and avoid any potential influencing effects of phototrophy in D. shibae, both organisms were cultivated in the light. Under these conditions, no bacteriochlorophyll is synthesised D.