Engineering Cupriavidus necator H16 for heterotrophic and autotrophic production of myo-inositol

Bioconversion of sustainable feedstocks to commodity chemicals is considered as an effective solution for transforming the fossil-based economy into a carbon-neutral model. Here, the CO2-fixing bacterium Cupriavidus necator H16 was exploited for myo-inositol production from renewable substrates. First, by introducing the glucose transportation system, the glucose consumption route was established. Second, two key enzymes involved in myo-inositol biosynthesis were screened and evaluated. A myo-inositol-producing strain was constructed via overexpression of myo-inositol-3-phosphate synthase from Saccharomyces cerevisiae and inositol monophosphatase from Escherichia coli. Finally, carbon flux redirection was achieved through disruption of Entner-Doudoroff pathway and poly(3-hydroxybutyrate) synthesis pathway, resulting in a final myo-inositol production of 520.2, 1076.3 and 1054.8 mg/L from glucose, glycerol and CO2, respectively. The myo-inositol production level from CO2 achieved here set up the record. This study underlines the potential of C. necator to be utilized as microbial factory for upcycling the renewable feedstocks and CO2 to high-value biochemicals.