Abstract Bacterially produced biodegradable polyhydroxyalkanoates with versatile properties can be achieved using different PHA synthase enzymes. This work aims to expand the diversity of known PHA synthases via functional metagenomics, and demonstrates the use of these novel enzymes in PHA production. Complementation of a PHA synthesis deficient Pseudomonas putida strain with a soil metagenomic cosmid library retrieved 27 clones expressing either Class I, Class II or unclassified PHA synthases, and many did not have close sequence matches to known PHA synthases. The composition of PHA produced by these clones was dependent on both the supplied growth substrates and the nature of the PHA synthase, with various combinations of SCL-and MCL-PHA. These data demonstrate the ability to isolate diverse genes for PHA synthesis by functional metagenomics, and their use for the production of a variety of PHA polymer and copolymer mixtures.