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Fig. 4 | Microbial Cell Factories

Fig. 4

From: Efficient Cas9-based genome editing of Rhodobacter sphaeroides for metabolic engineering

Fig. 4

a The PHB biosynthetic pathway of Rhodobacter sphaeroides. The annotation is based on KEGG. Enzymatic conversions are indicated by their EC numbers. Double arrowed reactions describe reversible reactions (ΔrG′° > − 30 kJ/mol [48]). Ac-CoA acetyl-CoA; AcAc-CoA acetoacetyl-CoA; (R)-3-HB (R)-3-hydroxybutanoate, (R)-3-HB-CoA (R)-3-hydroxybutanoyl-CoA, (S)-3-HB-CoA (S)-3-hydroxybutanoyl-CoA, Crot-CoA crotonyl-CoA; PHB: poly-β-hydroxybutyrate. The interrupted square indicates the metabolic step that is hypothesized to be catalysed by phaB and/or phbB. b Effect of the phaB (RSP_0747) and the phbB (RSP_3963) knockout, as well as of the combined knockout, on the C/N ratios of the generated mutants in nitrogen excess and limiting conditions on a defined medium. Lower C/N ratio’s indicate less PHB accumulation (Student’s t-test, *P < 0.05). c Effect of the phaB (RSP_0747) and the phbB (RSP_3963) knockout, as well as of the combined knockout, on the acids production and the PHB accumulation in Rhodobacter sphaeroides (Student’s t-test, ***P < 0.001). Concentrations of active biomass, PHB, pyruvate and oxo-glutarate were measured after 24 h cultivation in Sistrom’s minimal medium supplied with 1.0 g/L or 0.25 g/L of NH4Cl (Nitrogen excess and nitrogen limited conditions, respectively). Error bars indicate standard deviations from at least two replicates

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