PURPOSE: To simply obtain poly-3-hydroxylactic acid useful for medical materials, sustained release carriers, etc., and having biodegradability and biocompatibility by extracting a bacterial cell containing poly-3-hydroxylactic acid using acetonitrile, propionitrile, etc., as an extraction solvent.
CONSTITUTION: A bacterial cell containing poly-3-hydroxylactic acid [e.g. Protomonas extorquens K (FERM P-8395)] is subjected to batch culture in a medium using methanol as a carbon source so that feed of nitrogen becomes restriction factor of proliferation of bacterial cell and then, a humid bacterial body obtained by centrifuging the resultant cultured mixture is lyophilized to obtain a dried bacterial cell. Then, this dried bacterial cell is put in a pressure tube and acetonitrile or propionitrile is added as an extraction solvent to the pressure tube and the dried cell is extracted with the extraction liquid at an extraction temperature of ≥100°C for 1hr and then, cooled to 75°C and filtered with suction to separate the residue of bacterial cell and precipitation produced by cooling the filtrate to room temperature is filtered with the suction, washed and dried. Thereby, this poly-3-hydroxylactic acid is obtained using a safe, readily available and inexpensive solvent.
TAWARA TORAICHI
YOSHIDA SHOGO
