A process for the recovery of poly(hydroxyalkanoates) from Pseudomonads .1. Solubilization

Poly(hydroxyalkanoates) (PHAs) are bacterial storage polyesters, currently receiving much attention because of their potential as biodegradable and renewable plastics. Well known are poly(hydroxybutyrate) and its copolymers with hydroxyvalerate, which have been commercialised under the trademark Biopol. In addition to these rigid materials, the elastomeric medium-chain-length PHAs (mcl-PHAs) from fluorescent Pseudomonads are now emerging. Here we describe the development of a non-solvent based process for the recovery of mcl-PHAs from the biomass. This first paper addresses a procedure to solubilize the biomass, so that it can be separated from the particulate mcl-PHA. The solubilization procedure, involving heat, protease and detergent, leaves the peptidoglycan intact, which facilitates the separation. The purity of the resulting mcl-PHA exceeds 95%. In a subsequent paper, we utilize the solubilization procedure in a downstream process and we discuss the economics of the corresponding mcl-PHA production.