Continuous Production Mode as a Viable Process Engineering Tool for Efficient Poly(hydroxyalkanoate) (PHA) Bio Production
Poly(hydroxyalkanoates) (PHAs) constitute promising biomaterials for substituting plastics of fossil origin. Until now, all commercial processes for PHA production were based on discontinuous fed batch cultivation of prokaryotes. Such processes embody several shortcomings: unpredictable product quality, restricted possibility for supply of toxic carbon substrates, and, most of all, low volumetric productivity. Continuous PHA biosynthesis as a remedy was already investigated on laboratory scale for production of highly crystalline PHA homopolyesters as well as for elastomeric and even functional PHA copolyesters. Apart from enhanced productivity, chemostat processes are a feasible method to elucidate kinetics of cell growth and PHA formation under constant environmental conditions. In order to adapt the process engineering to the microbial kinetic characteristics for growth and PHA accumulation, continuous single and multistage approaches are reported.