Extraction of poly(.beta.-hydroxy butyric acid)
AssigneeImperial Chemical Industries PLC
InventorsJohn Walker, Jonathan R. Whitton
Life of this patent
Estimating the term…
Abstract
Poly (.beta.-hydroxy butyric acid), PHB, is extracted from a suspension of bacterial cells by causing the cells to flocculate, by pH modification, optionally with heating, and then extracting the PHB from the flocculated cells with a suitable extraction solvent. Flocculation of the cells renders subsequent separation of the PHB solution from the cell debris more facile. Preferably lipids are extracted from the flocculated cells before contact with the PHB extraction solvent.
Claims8
A process for the separation of poly(.beta.-hydroxy butyric acid), PHB, from an aqueous suspension of bacterial cells containing PHB wherein the PHB-containing cells are contacted with an extraction solvent in which PHB is soluble and the solvent having the PHB dissolved therein is separated from the cell debris, characterised in that the bacterial cells in the aqueous suspension are caused to flocculate by the step of reducing the pH of the suspension to a value in the range 2 to 5 by treatment with an acid, in combination with at least one of the steps (i) treatment of the suspension with alkali to increase its pH to a value in the range 8 to 12 before acidification, and (ii) heating the suspension to a temperature within the range 50.degree. to 200.degree. C. before or after acidification, and then the flocculated cells are separated from the aqueous medium prior to contact of the cells with the extraction solvent.
Dependencies are inferred from the claim text.