CHARACTERISTICS OF TRANSPOSON INSERTION MUTANTS OF MANDELIC ACID-UTILIZING PSEUDOMONAS-PUTIDA STRAIN A10L

A soil isolate, Pseudomonas putida strain A10L that utilizes mandelate via the mandelate pathway was mutagenized by transposon Tn5-Mob inser tion and a mutant 168 lacking mandelate racemase (MR) and a mutant 254 lacking benzoylformate decarboxylase (BFDC) were obtained, Expression of (S)-mandelate dehydrogenase (MDH), BFDC, NAD(+)-dependent benzalde hyde dehydrogenase (BDH) and NADP(+)-dependent BDH in the MR-lacking m utant was not affected by the insertion, and it was inducible similarl y to the wild type strain, On the other hand, expression of MR and MDH in the BFDC-lacking mutant was low and constitutive, and NAD(+)- and NADP(+)-dependent BDHs were produced at a rather high level under non- induced conditions by the mutant, Genes for MR (mdlA), MDH (mdlB), and BFDC (mdlC) were indicated to be organized in an operon in the order of mdlCBA. Optical resolution to obtain (R)-mandelate a useful synthon for pharmaceuticals, was shown to be performed with the MR-lacking mu tant.