Biosynthesis, purification and characterization of polyhydroxybutyrate from Botryococcus braunii kütz

• Poly hydroxyl butyrate was for the first time reported from Botryococcus braunii.
• PHB was characterized using TEM, FTIR, XRD and DSC-TGA analyses.
• The purity of the micro algal PHB was found to be 16.4%.
• Green synthesis of PHB from B. braunii provides advantages over other methods.
• The purified PHB was eco-friendly and cost-effective.

Polyhydroxybutyrate (PHB) is completely biodegradable which is metabolised by microorganisms in the soil as their sole food source in few years. The level of PHB up to 10.6% of algal dry weight is of great potential of the eco-friendly nature. Botryococcus braunii is mainly used for the production of biodiesel and is also capable of producing biopolymer polyhydroxy butyrate (PHB). In this study, Botryococcus braunii is used which generally produce PHB to around 20% of the dry weight. Three different microalgae were isolated from the fresh water of Kolavoi lake of Tamil Nadu. They were identified by their morphological features under the light microscope. The primary screening of PHB intracellular granules was made by using Nile red dye under a fluorescent microscope. Among them, Botryococcus braunii showed high accumulation of PHB granules. For authentic confirmation, the chloroform extracted PHB was analysed by FTIR, XRD and DSC−TGA analyses to characterize PHB with commercial biodegradable thermoplastic. This is the first report in B. braunii for its PHB production.