An efficient method for the application of PHA-poor solvents to extract polyhydroxybutyrate from Cupriavidus necator

There are many published studies presenting ethanol and acetone as PHAs-poor solvents, where these two solvents are shown to dissolve <2% (w/v) of PHAs at low temperatures. In this study, the suitability of ethanol and acetone for the recovery of PHB at different temperatures (from room temperature to near boiling point) in Cupriavidus necator was investigated. Experiments were performed using response surface methodology to examine the effects of different temperatures and heating incubation times on recovery percentage using the two solvents. The highest recovery percentage (92.3%) and product purity (up to 99%) were obtained with ethanol-assisted extraction at 76°C for 32 min of incubation time. Under these conditions the extracted PHB exhibited a molecular mass of 1.2 × 10⁶ . The present strategy showed that at temperatures near its boiling point, ethanol, as a nonhalogenated solvent, represents a good alternative to halogenated solvents, like chloroform, when PHB recovery is concerned. DSC analysis showed good thermal properties for ethanol- and acetone-extracted biopolymers. GC and ¹ H NMR analysis confirmed the extracted biopolymer to be polyhydroxybutyrate of good purity. © 2016 American Institute of Chemical Engineers Biotechnol. Prog., 32:1480-1486, 2016.