Cell growth and oxygen uptake of Escherichia coli and Pseudomonas aeruginosa are differently effected by the genetically engineered Vitreoscilla hemoglobin gene

Vitreoscilla hemoglobin is a good oxygen trapping agent and its presence in genetically engineered Escherichia coli helps this bacterium to grow bette r. Here, the potential use of this hemoglobin, for improving the growth and the oxygen transfer properties of Pseudomonas aeruginosa as well as Escher ichia coil, was investigated. To stably maintain it in both bacteria, a bro ad-host range cosmid vector (pHG1), containing the entire coding sequence f or Vitreoscilla hemoglobin gene and its native promoter on a 2.3 kb fragmen t, was constructed. Though at different levels, both bacteria produced hemo globin and while the oxygen uptake rates of vgb-bearing strains were 2-3-fo ld greater than that of non-vgb-bearing strains in both bacteria, the growt h advantage afforded by the presence of Vitreoscilla hemoglobin was somewha t varied. As an alternative to the traditional method of the improvement of oxygen transfer properties of the environment in which cells are grown, th e genetic manipulation applied here improved the oxygen utilization propert ies of cells themselves. (C) 2001 Published by Elsevier Science B.V.