Protocol for obtaining polyhydroxyalkanoates from microbial cultures: Production, quantification, and analytical assays

Polyhydroxyalkanoates (PHAs), a family of natural bacterial biodegradable biopolymers, constitute a promising alternative to conventional plastics. Here, we present a protocol to monitor bacterial growth and biopolymer accumulation in shaken flasks using two model bacteria, Pseudomonas putida KT2440 and Cupriavidus necator H16. We also describe steps to achieve high cell-density cultures in benchtop bioreactors using bioprocess engineering. Typical performance metrics include biomass concentrations of 6.5-7 g cell dry weight (CDW)/L and PHA titers of 4.2-4.5 g/L for P. putida and 3.5 g/L for C. necator. We then detail procedures for downstream processing, assessing monomer composition, and determining its thermal properties.