NOVELTY - Oil-water separating medium comprises a culture obtained by culturing a microorganism having APR-3 polymeric material producing ability, in a thiamin containing medium. The culture has specified sugar content, organic acid and sugar composition, does not contain amino sugar, uronic acid and protein, and has predefined molecular weight, spectral characteristics and viscosity.    USE - For oil removal from oil-polluted environment.    ADVANTAGE - The culture solution obtained by cultivating APR-3 producing microorganism in thiamin containing medium has a higher oil-water separability than that cultivated in other media. The obtained oil-water separating medium has high activity and is inexpensive. Oil from polluted environment can be removed efficiently and damage to environment is prevented.    DETAILED DESCRIPTION - A culture obtained by culturing a microorganism having APR-3 polymer producing ability in a thiamin containing medium, the polymer having oil and water separability, has the following characteristics;(i) sugar content (by phenol-sulfuric acid method): 64+/-2 weight %; (ii) amino sugar: undetectable (by Elson-Morgan method); (iii) Uronic acid: undetectable (by carbazole-sulfuric acid method); (iv) protein: undetectable (by ninhydrine method); (v) elemental analysis: carbon 40+/-2%, hydrogen 6+/-1% and trace amounts of nitrogen phosphorus and sulfur; (vi) the composition (molar ratio) of sugar and organic acid: galactose 1, glucose 5.6+/-0.1, succinic acid 0.6+/-0.1, pyruvic acid 2.5+/-0.1; (vii) molecular weight: at least 2x106; (viii) viscosity (by viscometron rotational viscometer, SS-2 rotor, 25degreesC, rotation speed 3-60 rpm, solvent pure water, 0.5 weight % solution of H type APR-3): 9000+/-1000 cP; (ix) solubility: soluble in water, easily soluble in alkali, insoluble in methanol, ethanol and acetone; (x) specific rotation (20degreesC): -17 to -15degrees; (xi) IR spectrum absorption band (cm-1): 2700-3700, 1730, 1600, 1400, 1160. An INDEPENDENT CLAIM is also included for oil and water separation method. The oil and water separating medium is made to contact an oil-water suspension.