Photoautotrophic Poly(3-Hydroxybutyrate) Production By A Wild-Type Synechococcus Elongatus Isolated From An Extreme Environment

The photoautotrophic poly(3-hydroxybutyrate) (PHB) production by cyanobacteria is an attractive option as it only requires CO2 and light. In this work, a new wild-type strain producing PHB, Synechococcus elongatus UAM-C/S03, was identified using a polyphasic approach. The strain was cultured in a photobioreactor operated under N-sufficiency conditions at different pH values (7 to 11) and fed with CO2 on demand. We also evaluated the production of PHB under N-starving conditions. Highest biomass productivity, 324 mg L-1 d-1, and CO2 capture, 674 mg L-1 d-1, were obtained at pH 7 and under N-sufficiency conditions. The strain accumulated 29.42% of PHB in dry cell weight (DCW) under N-starvation conditions without pH control, and highest PHB productivity was 58.10 mg L-1 d-1. The highest carbohydrate content registered at pH 8, 50.84% in DCW, along with a release of carbon-based organic compounds, suggested the presence of exopolysaccharides in the culture medium.