PRODUCTION OF ALPHA-HYDROXYCARBOXYLIC ACID OR ALPHA-HYDROXYAMIDE WITH MICROORGANISM

PROBLEM TO BE SOLVED: To obtain the subject compound useful as a raw material for medicines, agrochemicals, etc., by reacting an aldehyde with hydrogen cyanide at a low reaction rate on the action of a microorganism in an aqueous solution, while detecting the concentration of the hydrogen cyanide in the reaction solution and constantly maintaining the concentration of the hydrogen cyanide. SOLUTION: This α-hydroxycarboxylic acid or α-hydroxyamide of formula II (X is amide, carboxyl) is produced from the corresponding aldehyde of formula I [R is a (substituted) alkyl, a (substituted) alkenyl, a (substituted) alkoxy, a (substituted) aryl, etc.,] and hydrogen cyanide on the action of a microorganism in an aqueous medium. Therein, the hydrogen cyanide is continuously and/or intermittently supplied to the reaction solution so as to maintain the concentration of the cyanide ions within a constant range of 0.01-300mM, and the aldehyde is simultaneously supplied in a ratio of 0.98-1.05 mole per mole of the hydrogen cyanide. The obtained objective compound is industrially important as a raw material for synthesizing various kinds of medicines, agrochemicals, etc.