Polyhydroxyalkanoates (PHAs) in industrial applications

Polyhydroxyalkanoates (PHAs) are biodegradable polyesters produced by many bacteria that accumulate them as intracellular storage material in the cytoplasm. These polymers are potential candidate for substitution of petrochemical nonrenewable plastics for their biodegradable and nontoxic properties. Polyhydroxyalkanoate (PHA) can be synthesized by different strategies, such as microbial production by wild type or recombinant microorganisms, in vitro production via PHA synthase-mediated catalysis, or using genetically engineered plants. PHA accumulation in natural strains is favored by high availability of carbon source and a limited amount of macrocomponents (nitrogen, phosphate, oxygen) or microcomponents (sulfate, magnesium ions, and other trace elements). PHAs are applied in many fields, such as packaging, medicine, or agriculture, but the extensive application of the bioplastics is constrained by high production costs, especially for raw material, downstream processing, and polymer recovery. In this chapter, the progresses in production of PHA in natural strains and in engineered E. coli, Pseudomonas spp., Bacillus, Aeromonas, and other bacteria, such as the halotolerant Halomonas spp., are presented. In addition, the constrains on purification steps and the potential of high value applications are presented.