Cyanobacterial Polyhydroxyalkanoate Production: Status Quo and Quo Vadis?

Background: The article summarizes the present state of knowledge (status quo) for cyanobacterial polyhydroxyalkanoate (PHA) production by wild type and genetically engineered strains. Methods: The work elucidates particularities of the enzymatic background, and presents viable approaches to enhance productivity and quality of cyanobacterial PHA by implementing sophisticated feeding- and cultivation strategies. Conclusion: The needed route of march (quo vadis?) to turn cyanobacteria into potential cellular factories for large-scale PHA production is discussed. This encompasses enhanced engineering and process design, advanced photobioreactor developments, new cultivations regimes, efficient and sustainable downstream processing, and improvements on the genetic level. Finally, the selection of inexpensive reduced carbon substrates to be applied in mixotrophic cultivation processes provides for reduced production costs and, at the same time, allows to produce PHA copolyesters with enhanced material properties.