Synthesis, recovery and possible application of medium-chain-length polyhydroxyalkanoates: A short overview

Bacterial polyhydroxyalkanoates (PHAs) are polyesters of 3-hydroxyacids produced as intracellular granules by a large variety of bacteria, currently receiving much attention because of their potential as renewable and biodegradable plastics. The monomer units in these microbial polyesters are all in the R-configuration due to the stereospecificity of biosynthetic enzymes. Pseudomonads synthesise mainly medium-chain-length PHAs, formed of monomers of 6 to 14 carbons. The PHA monomer composition is influenced by the substrate added to the growth media and determines the physical properties of the plastic material. The capability of Pseudomonads to incorporate many different functional groups into the PHAs does extend their physical properties and potential applications, and suggests various possibilities to produce tailor-made polymers. The mcl-PHAs are of major interest for specific uses, where chirality and elastomeric property of the polymers are important. In this report we will focus on the biotechnological production, recovery and possible applications of mcl-PHAs.