Production and characterization of medium-chain-length polyhydroxyalkanoate copolymer from Arctic psychrotrophic bacterium Pseudomonas sp PAMC 28620

Arctic psychrotrophic bacterium Pseudomonas sp. PAMC 28620 was found to produce a distinctive medium-chain-length polyhydroxyalkanoate (MCL-PHA) copolymer when grown on structurally unrelated carbon sources including glycerol. The maximum MCL-PHA copolymer yield was obtained about 52.18 +/- 4.12% from 7.95 +/- 0.66 g/L, of biomass at 144h of fermentation when 3% glycerol was used as sole carbon and energy source during the laboratory-scale bioreactor process. Characterization of the copolymer was carried out using fourier transform infrared spectroscopy (FTIR), gas chromatography-mass spectrometry (GC-MS), proton (H-1) and carbon (C-13) nuclear magnetic resonance spectroscopy (NMR), gel permeation chromatography (GPC), differential scanning calorimeter (DSC) and thermo-gravimetric analysis (TGA). The copolymer produced by Pseudomonas sp. PAMC 28620 consisting of four PHA monomers and identified as 3-hydroxyoctanoate (3HO), 3-hydroxydecanoate (3HD), 3-hydroxydodecanoate (3HDD) and 3-hydroxytetradecanoate (3HTD). An average molecular weight of the copolymer was found approximately 30.244 kDa with polydispersity index (PDI) value of 2.05. Thermal analysis showed the produced MCL-PHA copolymer to be low-crystalline (43.73%) polymer with great thermal stability, having the thermal decomposition temperature of 230 degrees C-280 degrees C, endothermic melting temperature (T-m) of 172.84 degrees C, glass transition (T-g) temperature of 3.99 degrees C, and apparent melting enthalpy fusion (Delta H-m) about 63.85 J g(-1). (C) 2017 Elsevier B.V. All rights reserved.