Mitsubishi Rayon Company, Limited

Hisao Onishi

Ryozo Numazawa

Akihiro Sakimae

Yuri Kagawa

Takao Miyamori

Hitoshi Takeda

N-(3-acetylthio-2-D-methylpropionyl)-L-proline useful as a precursor of captopril, one of antihypertensive agents, is prepared by allowing thioacetic acid to react with methyl methacrylate to prepare racetalc methyl 3-acetylthio-2-DL-methylpropionate, contacting the propionate with cells of, for example, Pseudomonas in order to effect biological and asymmetric hydrolysis, extracting 3-acetylthio-D-2-methylpropionic acid and allowing the acid to react with L-proline.

Process for producing optically active carboxylic acid amide

High molecular weight hyaluronic acid can be efficiently produced by incorporating one or more compounds having at least one aromatic ring to which one or more hydroxyl groups are attached into a medium for producing hyaluronic acid by a bacterium capable of producing hyaluronic acid. By using this method, a sufficient amount of hyaluronic acid can be easily obtained without decomposing the high molecular structure of hyaluronic acid so that the process for isolating and purifying hyaluronic acid from the medium can be simplified.

Method of producing hyaluronic acid

A process for treating contaminated water containing BOD sources and nitrogen sources, which comprises supplying oxygen or oxygen-containing gas from one side of a gas-permeable membrane to grow microorganisms including aerobic bacteria and anaerobic bacteria on the other side of the gas-permeable membrane, and performing decomposition of the BOD sources and nitrification and denitrification simultaneously by the action of these microorganisms. Especially good results are obtained when a membrane composed of porous hollow fibers is used as the gas-permeable membrane.

Biochemical process for purifying contaminated water

Organic carboxylic acid ester represented by the formula (II): ##STR1## wherein R.sub.1 is an alkyl, an aralkyl or an aryl group; R.sub.2 is an alkyl group; R.sub.3 is an alkyl group; n is 1 or 2, are synthesized in racemic form, and then the acid ester (II) is treated with a source containing enzyme capable of rearranging with or without asymmetrically hydrolyzing ester bond until either a d-form or 1-form optically active carboxylic acid ester represented by the formula (II) with or without the antipode acid thereof is produced.

Process for preparing optically active carboxylic acids and antipode

Immobilized enzymes or microorganisms are prepared by dispersing lumps of ice containing an enzyme or microorganism in an organic solvent having a water-insoluble high-molecular weight substance dissolved therein, and then removing the organic solvent to entrap the ice lumps in the water-insoluble high-molecular weight substance. Deactivation of the enzyme or microorganism by the organic solvent is prevented by the enzyme or microorganism being entrapped in the lumps of ice.

Preparation of immobilized enzymes of microorganisms

Waste water containing organic pollutants is purified by biological treatment with aerobic microorganisms supported on hollow fibers having microporous walls through which oxygen is supplied to the microorganisms.

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Hiroshima, Japan

Hisao Onishi