CPC C08G 63/89 (2013.01) [C08G 63/06 (2013.01); C08G 63/90 (2013.01); C12P 7/625 (2013.01)] | 20 Claims |
1. A method for isolating polyhydroxyalkanoate (PHA) from a PHA-containing bacterial biomass, the method comprising the steps of:
(a) treating an aqueous suspension of the PHA-containing bacterial biomass with a minimal amount of sodium hypochlorite sufficient to lyse the PHA-containing bacterial biomass at a room temperature to provide a PHA-containing biomass lysate in an aqueous phase;
(b) separating the PHA-containing biomass lysate from the aqueous phase;
(c) washing the PHA-containing biomass lysate with water;
(d) removing water from the PHA-containing biomass lysate to provide a PHA-containing biomass cake having a water content of less than 70% w/w;
(e) washing the PHA-containing biomass cake with methanol to provide a PHA-containing biomass cake having a water content of less than 5% w/w;
(f) mixing the PHA-containing biomass cake with dimethyl carbonate (DMC) to provide a suspension of PHA-containing biomass in DMC;
(g) heating the suspension of PHA-containing biomass in DMC obtained in step (f) at a temperature from 70° C. to 90° C. for 1-3 hours under vigorous stirring to provide a suspension of cell debris and a PHA-containing DMC;
(h) separating the cell debris from the PHA-containing DMC;
(i) concentrating the PHA-containing DMC to provide a PHA-DMC concentrate;
(j) adding a non-solvent at a temperature from −20° C. to 0° C. to the PHA-DMC concentrate and mixing to provide a suspension of a PHA precipitate in DMC and the non-solvent:
(k) separating the PHA precipitate from the DMC and the non-solvent;
(l) washing the PHA precipitate separated in step (k) with the non-solvent at the temperature from −20° C. to 0° C.; and
(m) drying the PHA precipitate washed in step (l) to provide a PHA isolated from the PHA-containing bacterial biomass.
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