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

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 38.8 g/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-Iysine (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 3.1 g/liters of Lys and 5.6 g/liters of Thr in 72 h in a 5-liter jar fermentor.