Production of biopolymers from microalgae and cyanobacteria

Abstract Over the past few decades, plastic-derived pollution has been recognized as a major environmental issue because the use of conventional plastics results in vast amounts of waste as well as in fossil-fuel depletion. Biodegradable and biobased polymers are a promising alternative to conventional plastics. In this context, polyhydroxyalkanoates (PHAs) are bioplastics with similar mechanical and thermal properties to petroleum-based plastics which can be used in a wide range of applications. Several studies have reported the accumulation of PHAs in the biomass of microalgae and cyanobacteria. Under optimal conditions for PHA accumulation, that is, nutrient limitation, and optimal light intensity, PHA content can significantly increase, achieving 85% of dry biomass weight. Downstream recovery of PHAs is also a critical step that affects the properties and the yield of PHAs. Bioplastic production from microalgae and cyanobacteria on a commercial scale is still limited due to its high cost, with the cultivation medium accounting for up to 50% of the total production cost. The use of wastewater as a growth medium can improve the economic feasibility and sustainability of PHA production from microalgae and cyanobacteria and contribute to a more circular economy.