Extraction of poly(3-hydroxybutirate) from Priestia megaterium using non-halogenated solvents: A comparative performance analysis

Solvent extraction using chloroform is the most common industrial process for poly(3-hydroxybutyrate) (P(3HB)) recovery from dried biomass, and still a major barrier to expanding the commercial application of this biodegradable biopolymer. Consequently, there is great interest in alternative non-halogenated solvents for this process and some relevant related results are available in the literature for P(3HB) recovery from Gram-negative bacteria. This work evaluated the potential of a set of non-halogenated solvents for the extraction of P(3HB) from Priestia megaterium, a Gram-positive bacterium of great potential for P(3HB) production. Ethyl acetate (EtAc), methyl ethyl ketone (MEK), dimethyl carbonate (DMC), dimethyl sulfoxide (DMSO), N,N-dimethylacetamide (NNDA), 2-heptanone (2-Hp), propylene carbonate (PC), and isoamyl propionate (IAP) were tested. Preliminary solubilization tests using commercial P(3HB) showed that EtAc, MEK, DMC and IAP had lower P(3HB) solubilization capacity (below 0.08 g/L for EtAc, MEK, and DMC; 1.3–2.5 g/L for IAP) than DMSO (65–70 g/L) and PC, 2-Hp and NNDA (>100 g/L). Then, only DMSO, PC, 2-Hp, and NNDA were evaluated in recovery tests with intracellular P(3HB). DMSO was not selective for P(3HB), causing digestion of cell wall components. PC, 2-Hp, and NNDA outperformed chloroform, but NNDA stood out for its remarkably higher recovery (98.5 %, 30 min, 140 ºC).