Production of medium-chain-length polyhydroxyalkanoates by Pseudomonas chlororaphis subsp. aurantiaca: Cultivation on fruit pulp waste and polymer characterization

Pseudomonas chlororaphis subsp. aurantiaca DSM 19603 was cultivated on apple pulp, a glucose- and fructoserich waste generated during juice production, to produce medium-chain length polyhydroxyalkanoates. A cell dry mass of 8.74 ± 0.20 g/L, with a polymer content of 49.25 ± 4.08% were attained. The produced biopolymer was composed of 42.7±0.1mol% 3-hydroxydecanoate, 17.9±1.0mol% 3-hydroxyoctanoate, 14.5±1.1mol% 3- hydroxybutyrate, 11.1±0.6 mol% 3-hydroxytetradecanoate, 10.1±0.5 mol% 3-hydroxydodecanoate and 3.7± 0.2 mol% 3-hydroxyhexanoate. It presented low glass transition and melting temperatures (−40.9 ± 0.7 °C and 42.0±0.1 °C, respectively), and a degradation temperature of 300.0±0.1 °C, coupled to a lowcrystallinity index (12.7±2.7%), amolecularweight (Mw) of 1.34 × 105±0.18×105 Da and a polydispersity index of 2.70±0.03. The biopolymer's filmswere dense and had a smooth surface, as demonstrated by Scanning ElectronMicroscopy. They presented a tension at break of 5.21 ± 1.09 MPa, together with an elongation of 400.5 ± 55.8% and an associated Young modulus of 4.86 ± 1.49 MPa, under tensile tests. These attractive filming properties of this biopolymer could potentially be valorised in several areas such as the fine chemicals industry, biomedicine, pharmaceuticals, or food packaging

Keywords

fruit pulp waste polyhydroxyalkanoates (PHA) Pseudomonas chlororaphis

URI

http://hdl.handle.net/10400.5/23782

Citation

Pereira JR, Araújo D, Freitas P, Marques AC, Alves VD, Sevrin C, Grandfils C, Fortunato E, Reis MAM, Freitas F (2021). Production of medium-chain-length polyhydroxyalkanoates by Pseudomonas chlororaphis subsp. aurantiaca: Cultivation on fruit pulp waste and polymer characterization. International Journal of Biological Macromolecules, 167:85-92