L-PHENYLALANINE PRODUCTION BY DOUBLE AUXOTROPHIC MULTIANALOGUE-RESISTANT MUTANT OF ARTHROBACTER-GLOBIFORMIS

Tryptophan-plus-tyrosine double auxotrophic mutants resistant to fluor ophenylalanine (PFP) and beta-2-thienylalanine (TA) were isolated from a biotin-requiring glutamate-producing Arthrobacter globiformis. The mutants were found to produce L-phenylalanine in mineral salts medium. Further improvement of L-phenylalanine production was achieved by iso lation of mutants resistant to 5-methyltryptophan (MT) and 3-nitrotyro sine (NT) from a double auxotrophic PFP' and TA' mutant. Under optimal cultural condition one mutant yielded 9.6 g phenylalanine per L mediu m in flask culture. Enzymic activity of regulatory enzymes (deoxy-D-ar abino-heptulosonate-7-phosphate synthase, chorismate mutase and prephe nate dehydratase) were observed in the wild type, double auxotroph and double-auxotrophic multianalogue-resistant mutant.