Abstract

Pseudomonas aeruginosa MTCC 7925, a sludge isolate, was found to synthesize a novel short-chain-lengthlong- chain-length (SCL-LCL) co-polymer with 3-hydroxybutyric acid (3HB), 3-hydroxyvaleric acid (3HV), 3- hydroxyhexadecanoic acid (3HHD) and 3-hydroxyoctadecanoic acid (3HOD) as constituents. Under batch mode study, cells harvested at the stationary phase of growth depicted maximum PHAs accumulation, i.e. 24% of dry cell weight (dcw) at 48 h of incubation. The co-polymer accumulation was raised to 49% (dcw) under 2% ethanol-supplemented condition. A further, rise up to 78% (dcw) was recorded by optimizing the critical variables by Response Surface Methodology (RSM). When palm oil and its cakes were used as carbon sources, yield of 5.9 g/l was achieved, which was almost 85-fold higher against control. The thermal and mechanical properties of the polymer are comparable with polypropylene and polyethylene, thus opening new possibilities for various industrial applications.

Keywords: Inexpensive carbon sources, N-deficiency, P-deficiency, PHAs, Pseudomonas aeruginosa MTCC 7925, RSM, SCL-LCL-PHA co-polymer