Abstract

Novel short-chain-length-long-chain-length polyhydroxyalkanoate (SCL-LCL-PHA) copolymer production was examined with Pseudomonas aeruginosa MTCC 7925 under supplementation of non-edible oils such as karanja, jatropha, mahua, and castor oils, and their respective cakes for cost reduction. Polymer yield reached up to 4.66 g/l (63.7% dry cell wt., dcw) with a mol fraction of 89.7:4.2:2.7:3.4 of 3- hydroxybutyric acid (3HB): 3-hydroxyvaleric acid (3HV): 3-hydroxyhexadecanoic acid (3HHD): 3-hydroxyoctadecanoic acid (3HOD) units under the interactive condition of low nitrogen concentration with 0.5% (v/v) jatropha oil in combination with its cake extract, followed by 3.94 g/l (59.6% dcw) with a mol fraction of 91.6:3.3:2.5:2.6 of 3HB: 3HV: 3HHD: 3HOD with castor oil and its cake extracts. The novel co-polymer not only depicted material properties analogous to the common plastics but also better melting temperature (T_m), glass-transition temperature (T_g), elongation-to-break value and Young’s modulus than the homopolymer of poly-3-hydroxybutyrate (PHB). As compared to our previous report where palm oil and its cakes were used, a cost reduction of 54% was observed with the non-edible jatropha oil with its cakes. This opens up possibility for further study at pilot-scale level for low-cost production and future recommendations.

Keywords: Low-cost carbon sources, NH₄NO₃, KH₂PO₄, Polyhydroxyalkanoates, Pseudomonas aeruginosa MTCC 7925, Non-edible oils, SCL-LCL-PHA co-polymer

Graphical Abstract