Engineering Biosynthesis Mechanisms for Diversifying Polyhydroxyalkanoates

Polyhydroxyalkanoates (PHA) are a family of diverse biopolyesters synthesized by bacteria. PHA diversity, as reflected by its monomers, homopolymers, random and block copolymers, as well as functional polymers, can now be generated by engineering the three basic synthesis pathways including the acetoacetyl-CoA pathway, in situ fatty acid synthesis, and/or β-oxidation cycles, as well as PHA synthase specificity. It is now possible to tailor the PHA structures via genome editing or process engineering. The increasing PHA diversity and maturing PHA production technology should lead to more focused research into their low-cost and/or high-value applications.

TrendsAt present, PHA diversity is achieved by various PHA synthases with diverse specificities. It is highly desirable to assemble a platform PHA-producing bacterium containing various PHA synthases with ‘on and off’ inducible functions such that we can use the same bacterium for producing various PHAs under the same or different growth conditions.Halomonas spp. are strong candidates for both low-cost PHA and high value-added PHA production owing to their robustness and ability to grow to high cell density under open and continuous process conditions. It is highly desirable to assemble various PHA synthesis pathways in a suitable Halomonas sp. to achieve reduced production cost and diversity.Halomonas spp. have long been overlooked by industrial biotechnology community. It is time to develop suitable synthetic- and systems-biology approaches for Halomonas spp.