Abstract

BACKGROUND The aim of this study was to evaluate changes in the composition of poly-3-hydoxybutyrate-co-3-hydroxyvalerate (PHBV) by the polyhydroxybutyrate (PHB) overproducing mutant OPNA of Azotobacter vinelandii cultured under different conditions. RESULTS The oxygen transfer rate (OTR) significantly affected PHBV composition in cultures in shaken flasks; the highest content of 3-hydroxyvalerate (3HV; 28%) was achieved from cultures developed at an OTRmax of 5.87 mmol L-1 h(-1). In the bioreactor, cultures were grown under oxygen-limited conditions and different OTRs, varying the agitation rate. The highest PHBV accumulation (85%) was achieved at a low OTRmax (4.96 mmol L-1 h (-1)), whereas the maximum content of 3HV (8.5 mol%) was obtained at a higher OTRmax (20.3 mmol L-1 h(-1)). The OPNA strain produced a copolymer of ultra-high molecular weight. CONCLUSIONS Our results reveal that increasing the OTRmax raises the molar fraction of 3HV in the PHBV copolymer. Therefore, the manipulation of OTR could be a feasible strategy to produce PHBV copolymers with different monomeric compositions at industrial level. (c) 2021 Society of Chemical Industry (SCI).