Approaches for enhancing extraction of bacterial polyhydroxyalkanoates for industrial applications

Abstract

Poly(3-hydroxybutyrate) [P(3HB)] and others polyhydroxyalkanoates (PHAs) are recovered from the cells after their accumulation, in the production phase. The impact of PHA extraction may represent more than 50% of total production process. To ensure proper removal of the bioplastic from the bacterial cells several unitary operations must be performed in the extraction process. In addition, one also need to take in to consideration: reduction of product losses during processing, preservation of the physicochemical properties of the biopolymer, obtaining a highly pure product, use of low toxicity solvents/chemicals. In this case, PHA extraction methods include: chemical methods by using solvents, chemical digestion and aqueous system of two phases; mechanical methods with high pressure homogenization, ball mill, French press and ultrasound; biological methods, with enzymatic digestion, digestion by bacteria and predatory larvae or single cell protein; or a combination of these methods. This chapter discusses both classical and innovative methods for recovering/purifying PHAs, emphasizing yield, purity and the effect on the properties of the obtained biopolymers.