Fig. 5

Metabolome profiling of the selected succinate producing strains of S. elongatus PCC 11801 in exponential growth phase. Fold change of the metabolite pool sizes with respect to the wild-type strain with data arranged according to major metabolic pathways or metabolite categories: a Calvin–Benson–Bassham (CBB) cycle; b TCA cycle and related metabolites. c Major storage molecules and their precursors, d nucleotide sugars, e nucleotides, f glutathione, NAD⁺ and NADP. Metabolite pool size in the engineered strains with respect to wild-type. All the data, barring glycogen, was collected using liquid chromatography coupled to high resolution mass spectrometry (HR-LC/MS). Cyanobacterial cultures were grown under 1% CO₂ in a shaker and samples drawn in exponential growth phase (OD₇₃₀ ~ 0.6) for metabolite extraction. The fully ¹³C labeled metabolite extract from PCC 11801 wild-type was used as the internal standard to use the isotopic ratio method of relative quantification. Further, ratio of pool size in the recombinant strain to that in the wild-type was obtained and The metabolites presented in this study were identified at MS2 level using the MS-DIAL and MetDIA tool [70, 71]. The data for metabolites with a fold change of > 1.5 or less than 0.66 and a p-value of < 0.05 using t-test in at least one of succinate producer strains are shown. Averages for three biological and three technical replicates (n = 9) are shown for clarity. Glycogen content was estimated as reported previously [75]. Details of the metabolites in Additional file 1: Table S6