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.