L-PHENYLALANINE PRODUCTION BY DOUBLE-AUXOTROPHIC ANALOG RESISTANT MUTANTS OF ARTHROBACTER-GLOBIFORMIS

Three tryptophan plus tyrosine double-auxotrophic mutants were isolate d by NTG treatment of a biotin requiring glutamic acid producing Arthr obacter globiformis. The mutants were found to excrete phenylalanine i n mineral salt medium. Further improvement of L-phenylalanine producti on has been achieved by isolation of mutants resistant to analogue bet a-2-thienylalanine (TA) from these double auxotrophs. Thiamine HCl at 0.1 mM/ml level and penicillin at 50 IU/ml increased the yield of phen ylalanine. Tween-80 at 0.1 mug/ml was found to be best surfactant for phenylalanine production by these mutants.