Fig. 4

Shaking flask biomass growth of Synechococcus 2973 in the presence of carbon sources. a Growth rate (h⁻¹) of Synechococcus 2973 in two conditions when fed with 4 g L⁻¹ sodium bicarbonate and 6 mM of malate (MAL), acetate (AC), citrate (CIT), OAA, alpha-ketoglutarate (aKG), and a mix. Standard deviation is calculated from biological duplicates. There was no significant difference between growth rates. b Percent ¹²C-enrichment in amino acids through provision of 4 g L⁻¹ of ¹³C-bicarbonate and 6 mM of unlabeled organic acids in SF cultures (labeling for 48 h) compared against the control of just 4 g L⁻¹ of ¹³C-bicarbonate. The amino acids were chosen because of their direct relation to key metabolic precursors (Ala->PYR, Ser->3PGA, Phe->PEP/E4P, Glu->α-KG, Asp->OAA). [M-57] represents the mass signals of unlabeled amino acid (without fragmentation by GC–MS). Note: Synechococcus 2973 used unlabeled organic carbon sources to synthesize proteinogenic amino acids, the [M-57] % of amino acids increased compared to the control sample that was only fed with ¹³C-bicarbonate. Standard deviations are a result of biological duplicates *represents a p value of < 0.02 using two-tailed equal variance Student’s t Test