Efficient recovery of thermostable polyhydroxybutyrate (PHB) by a rapid and solvent-free extraction protocol assisted by ultrasound.

Nowadays, there are great research interest in polyhydroxybutyrate (PHB) recovery protocols that reduce the use of organic solvents and efficiently recover this bacterial biopolymer. The present study reports an extraction protocol assisted by ultrasound, which is a rapid protocol that increases the amount of polymeric matter extracted, reduces the cellular digestion step with sodium hypochlorite and eliminates the use of organic solvents. Likewise, characterization studies by Fourier transform infrared spectroscopy (FTIR), proton nuclear magnetic resonance spectroscopy (1H NMR), differential scanning calorimetry (DSC), and X-ray diffraction (XRD) demonstrated that the biopolymer recovered by this protocol is PHB homopolymer with a major thermal-resistance and crystalline properties. Besides, in this study are reported the thermic and crystalline differences between the PHB obtained from the fermentation of complex carbohydrates (agavins) and simple sugars. The biopolymer obtained by this rapid extraction protocol would be suitable for ecological and biomedical applications, due to the low melting temperature, less than 50% crystallinity, and the lack of lipopolysaccharides. Therefore, this extraction protocol might represent an alternative to the traditional protocol based on NaOCl-chloroform and is part of the green trend to improve the PHB production.