Optimizing the biosynthesis of renewable polyhydroxyalkanoate copolymer containing 3-hydroxyvalerate by Massilia haematophila using statistical modeling

Abstract

Polyhydroxyalkanoate (PHA) is a microbial storage polymer that is naturally produced by certain bacteria. This is the first study on the ability of this particular species Massilia haematophila to synthesize a PHA copolymer containing 3-hydroxyvalerate (3HV) monomer. Using the statistical design on Massilia haematophila UMTKB-2, this study highlights the optimization of poly(3-hydroxybutyrate-co-3-hydroxyvalerate), P(3HB-co-3HV), copolymer production for shaken-flask cultivation. Moreover, the mechanical and thermal features of the polymers were determined. The production of P(3HB-co-3HV) by Massilia haematophila UMTKB-2 using optimal conditions provided by response surface methodology (RSM) yielded 5.0 g/l of P(3HB-co-7 mol% 3HV), which was higher than the value obtained from unoptimized conditions such as 4.40 g/l of P(3HB-co-4mol% 3HV). This result showed a 14% increase in copolymer concentration and a two-fold increase in 3HV composition. In this study, the P(3HB-co-3HV) synthesized was determined as a block copolymer and its thermal properties were better than P(3HB). Using RSM, the optimization conditions were successfully obtained for this bacterium, and this result is a starting platform for additional studies of a larger scaled PHA production from Massilia haematophila UMTKB-2 using bioreactors.