Amino Acid Production from Methanol by Methylobacillus glycogenes Mutants : Isolation of L-Glutamic Acid Hyper-producing Mutants from M. glycogenes Strains, and Derivation of L-Threonine and L-Lysine-producing Mutants from Them

Abstract

L-Glutamic acid (Glu) hyper-producing mutants were isolated from Methylobacillus glycogenes ATCC 21276 and ATCC 21371 during the screening of amino acid auxotrophs. iA111, derived from ATCC 21276, and 1009 (Phe^-), derived from ATCC 21371, produced about 10 times as much Glu as the wild type strains. The highest producer, RV3, a phenylalanine auxotrophic revertant of 1009, produced 38.8g/liters of Glu in 84h in a 5-liter jar fermentor. iA111 and 1009 were mutagenized, and L-threonine (Thr) producing mutants were isolated among Thr and L-lysine (Lys) analog-resistant strains. The highest Thr producer derived from iA111, AL119 (AHV+Lys^R), produced 11.0g/liters of Thr in 72h in a 5-liter jar fermentor. AL119 was further mutagenized, and a Thr and Lys producer, DHL 122 (DHL^R), was isolated. DHL 122 co-produced 3.1g/liters of Lys and 5.6g/liters of Thr in 72h in a 5-liter jar fermentor.