A Newly Isolated Microorganism Producing D-β-Acetylthioisobutyric Acid from Methyl DL-β-Acetylthioisobutyrate

D- beta -acetylthioisobutyric acid (DAT) is an important key-intermediate for the chemical synthesis of various pharmaceuticals such as Captopril which are used for the treatment of hypertension and congestive heart failure. We have attempted the isolation of soil microorganisms producing cells giving higher activity in comparison with the cells of P. fluorescens IFO 3081. The soil sample was suspended in tap water and then one drop of the soil suspension was spread on an agar plate of a medium (pH 6.8) consisting of 10 g of Polypepton and 5 g of NaCl in per liter of tap water. The DAT producing ability of a colony appearing on the plate was tested by a resting cell reaction. From many colonies tested, one strain, MR-2068, was selected as the best DAT producer. By the studies of the morphological characteristics and biological analyses, the strain MR-2068 was identified as Pseudomonas putida . Compared with Pseudomonas fluorescens IFO 3081, P. putida MR-2068 could produce highly active cells containing a thermostable esterase so that DAT was produced effectively.