THE MICROBIAL-PRODUCTION OF POLY(HYDROXYALKANOATES) FROM TALLOW

The bacteria Pseudomonas oleovorans, P. resinovorans, P. putida, and P . citronellolis were evaluated for their ability to grow and produce p oly(hydroxyalkanoates) (PHA) using tallow free fatty acids and tallow triglyceride as carbon substrates. Tallow free fatty acids supported c ell growth and PHA production for all four organisms, yielding PHA con tents of 18%, 15%, 19% and 3% of their cell dry weights for P. oleovor ans, P. resinovorans, P. putida, and P. citronellolis respectively. On ly P. resinovorans, however, was able to grow and produce PHA polymer. with cells attaining a PHA content of 15% of their cell dry weight, u sing unhydrolyzed tallow as the substrate, Extracts from 46-h cultures of P. resinovorans were found to have a higher esterase activity (12. 80 units mu l(-1)min(-1)) compared to the activities found for culture s of P. oleovorans, P. citronellolis, and P. putida (< 0.03 units mu l (-1)min(-1)). Polymer repeat-unit compositions were determined by GC a nalysis of the beta-hydroxymethyl esters of hydrolyzed PHA, and ranged in carbon-chain lengths from C-4 to C-14, with some mono-unsaturation in the C-12 and C-14 side-chains. PHA compositions were similar for t he polymers obtained from all four organisms, with repeat units of cha in lengths C-8 and C-10 predominating.