Metabolic engineering of Cupriavidus necator using sucrose phosphorylase pathway for polyhydroxybutyrate production from sucrose.

Sucrose-rich feedstocks are the most suitable raw materials for the production of biodegradable polymers like Polyhydroxyalkanoates (PHAs). Cupriavidus necator, a versatile microorganism with natural ability to accumulate poly(3-hydroxybutyrate) (PHB), has been shown to utilize a diverse set of carbon sources including sugars, oils, and gaseous feedstock like CO₂. However, both wild-type and mutant strains of C. necator cannot metabolize sucrose, limiting its utility in industrial production using sucrose-rich feedstocks. We developed metabolically engineered strains of C. necator for sucrose utilization by introducing sucrose phosphorylase pathway. Among all the recombinant strains, C. necator harbouring sucrose phosphorylase from Rhizobium vitis (CN-SPrv) along with sucrose permease and phosphoglucomutase from Escherichia coli demonstrated the most efficient utilization of sucrose. The CN-SPrv strain was evaluated for the utilization of sucrose using cane biosyrup and resulted in 60 g/L of PHB titer and 31 % yield on a consumed sugar basis in fed-batch mode of fermentation. This is the first report on metabolic engineering of C. necator using the sucrose phosphorylase pathway for PHB production.