L-Serine Production by Temperature-sensitive Mutants of Methanol-utilizing Bacterium Pseudomonas MS 31

Temperature-sensitive mutants producing L-serine efficiently from glycine were obtained from the facultative methylotroph Pseudomonas MS 31. Forty-five mutant strains showed adequate growth on methanol at 30°C but little or no growth at 37°C. Fourteen of these mutants produced L- serine more efficiently than the wild-type strain. The typical mutant strain ts 162 showed a high conversion rate in glycine-to-L-serine when the cultivation temperature was changed from a permissive (30°C) to non-permissive state (38?42°C) together with the addition of glycine and methanol after adequate growth. The mutant strain accumulated 6.8 mg L-serine from 12 mg glycine per ml culture under optimum conditions. The reduction of L-serine degrading activity in the mutant strain seemed to contribute to the high productivity of L-serine.