passages.id: split_5_test_3424_passage
passages.type: progene_text
passages.text: When a feedback - resistant N-acetylglutamate synthetase gene ( argA214 ) was placed under the control of the arabinose - inducible promoter , either in the chromosome or on a multicopy plasmid in the cell , the combination of overexpression of argA214 with an argF argI argR triple knockout mutation had an additive effect on L-ornithine production but only when exogenous glutamate was present .