Effects of carbon substrates on biodegradable polymer composition and stability produced by Delftia tsuruhatensis Bet002 isolated from palm oil mill effluent

The effects of carbon substrate (C8:0-C18:1) on the biosynthesis and the properties poly-3-hydroxybutyrate and its copolymer (PHA) produced by Delftia tsuruhatensis Bet002 were investigated. Growth-associated accumulation yielded PHA at 76.7% cell dried weight with molecular weight ranging from 131 to 199 kDa. Carbon source type also influences the thermal stability of the PHA. The molar concentration ratio of carbon to nitrogen source has little effect on the PHA composition, but affected the biomass, PHA yield and polymer degradation stability. In general, polymer composition of even and odd carbon atom chain length (C4-C10) was obtained. The PHA produced is semi-crystalline polymer with good thermal stability with thermal degradation temperature (Td) 269.8 to 391.8 (±0.2) °C, melting temperature (Tm) 163.6 to 177.4 (±0.2) °C, glass transition temperature (Tg) −1.0 to 4.4 (±0.2) °C and apparent melting enthalpy of fusion (ΔHf) of 53.2 to 210.9 (±0.1) J g−1.