Patent ID: 7582456

Claim:
A method for directly separating and purifying polyhydroxyalkanoates in cells from a bacterial fermentation liquid, which comprises the steps of: a) physically pretreating a fermentation liquid containing cells to cause the walls of the cells to break; b) adjusting the pH value of the pretreated fermentation liquid from step a) to an alkaline condition; c) adding anionic surfactant to the solution of step b) and subjecting the solution to agitation; d) separating and extracting coagulated precipitate from the solution in step c); and e) washing and drying the coagulated precipitate, wherein the physical pretreatment includes mechanically breaking the cell walls or ultrasonically breaking the cell walls, and wherein steps b) and c) are interchangeable; wherein a coagulating agent is added in the step c) and wherein the coagulating agent comprises at least one of sodium polyacrylate, modified starch or polyamine.