Study on Synthesis of PHB by Moderate Halophile and Aqueous Extraction of PHB

Abstract

PHB (Poly-β-hydroxybutyrate) has been widely in the areas of industrial packaging, pharmacy and agriculture. Currently, its production cost, especially in extraction and purification are high. A moderate halophilic bacterium was used for PHB synthesis and an aqueous extraction method based on osmotic downshock was investigated in this paper to further improve the extraction efficiency. PHB synthesised by moderate halophile with certain NaCl concentration can be released with cell lysis by osmotic downshock. Meanwhile the high temperature, ultrasonic and SDS (Sodium dodecyl sulfate) can enhance the release. After 48 h of fermentation, the production of PHB by Halomonas salina was 6.5 g/L. The extraction rate of PHB was 24.6% with osmotic downshock and 35.4% with additional ultrasonic assistance at 65 °C. A further addition of 0.5% SDS made the extraction rate increase to 75.4%. Thereinto, the addition of 6% NaCl had significantly improved the aqueous extraction rate to 92.3%.