Recovery of poly(3-hydroxybutyrate) produced from Cupriavidus necator strain A-04 using environmental friendly solvents

Abstract

The use of environmental friendly solvents to recover polyhydroxyalkanoates (PHAs) from microbial cells is one of important factors for the development of efficient and sustainable technology for industrial production process. In this study, selected environmental friendly solvents: 2-methyl tetrahydrofuran, 1,3-propanediol, 1,3-dioxolane and ethyl lactate, were investigated to recover polyhydroxybutyrate (PHB) from Cupriavidus necator strain A-04 and compared that with the use of chloroform. The PHB recovery was investigated with dried cells and wet cells at volumes ranging from 2 mL to 40 mL using a PHB to solvent ratio of 5% (w/v). Cells contained intracellular PHB was prepared by batch cultivation in 5 L fermentor. Based on PHB extraction from dried cells at 80 °C for 6 h, 1,3-dioxolane gave 84.3±5.4% of purity with 86.3±4.0% of recovery. Next, water was used as plasticizers that can cause phase separation of PHB film from the solvent mixture and increase the purity up to 99.2±1.4%. To eliminate step of cell drying, the same recovery conditions were applied to extract PHB from wet cells and 98.5±8.6% of purity with 63.4±3.9% of recovery were obtained. To evaluate the quality of purified PHB, thermal properties, mechanical properties and molecular weight distribution were tested. It was found that our developed recovery method provide similar quality of PHB film compared with those of PHB from chloroform extraction and commercial PHB.