Microbial production of polyhydroxyalkanoate from soy sauce oil, a byproduct of soy sauce manufacturing

Cupriavidus necator is capable of producing substantial amounts of polyhydroxyalkanoates (PHAs) from various feedstocks. Nevertheless, no documented accounts exist on the utilization of soy sauce oil. Cupriavidusnecator cultured in a soy sauce oil-supplemented (1.5 wt%) nitrogen-limited mineral salt medium at 30 °C for 4 days yielded a maximum poly(3-hydroxybutyrate) content and production of 63.7 ± 2.45 wt% and 2.3 ± 0.17 g/L, respectively. Recombinant C. necator PHB¯4 harboring PHA synthase from Aeromonas caviae cultured under identical conditions for 3 days exhibited peak poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) [P(3HB-co-3HHx)] content and production of 46.3 ± 10.9 wt% and 2.0 ± 0.5 g/L, respectively. The P(3HB-co-3HHx) productivity and 3HHx mole fraction are analogous to the outcomes achieved with vegetable oils. The molecular weights and thermal properties of the synthetic PHAs were comparable to those of conventional PHAs. These findings endorse the use of soy sauce oil as a sustainable feedstock for bioplastic production.