Abstract

Polyhydroxyalkanoates are biopolymers which are naturally produced by a range of different microorganisms. Industrial scale application of these natural polyesters has been hampered by the cost and availability of renewable starting materials. One potential source of such a substrate could be plant oils, which could provide a sustainable source of carbon for medium chain length polyhydroxyalkanoate production as they are both renewable and inexpensive. No study has undertaken a comparative study of the use of major European and global commodity plants oils and products of their hydrolysis as substrates for PHA production. Several medium chain length polyhydroxyalkanoate producing Pseudomonas strains; Pseudomonas putida KT2440, CA3, GO16, Pseudomonas chlororaphis 555 and the short chain length polyhydroxyalkanoate producing strain Ralstonia eutropha H16 were screened for their ability to utilise a range of common plant oils (olive, sunflower, rapeseed, coconut and palm oils) as a sole source of carbon and energy for growth and PHA accumulation. R. eutropha H16, P. putida GO16 and P. chlororaphis could grow and produce PHA on the plant oils. In order to evaluate the ability of these strains to utilise plant oil derived fatty acid mixtures as a sole source of carbon the oils were hydrolysed and the resulting fatty acid mixtures tested for growth and PHA accumulation. All strains were capable of growth and PHA production on these mixtures. Finally in order to evaluate and directly compare the productivity and economic attractiveness of these two approaches to PHA production, a Pseudomonas strain was selected along with rapeseed oil and its corresponding fatty acid mixture for bioreactor trials to achieve high cell density and high PHA productivity which has not been achieved previously.