Preparation of L(+) β‐hydroxyisobutyric acid by bacterial oxidation of isobutyric acid

A process for the bacterial oxidation of isobutyric acid to L(+) β‐hydroxyisobutyric acid has been developed. The strain of Pseudomonas putida (ATCC 21244) used in this fermentation was isolated from local soil. The process was carried out in a 15‐liter fermentor over a period of 70 hr and produced L(+) β‐hydroxyisobutyric acid in conversions as high as 48%. Hydroxylation of the methyl group of isobutyric acid has special interest because it is difficult to perform chemically. The useful chemical syntheses of β‐hydroxyisobutyric acid available at present do not start with isobutyric acid and are not stereospecific.