Effects of Vitreoscilla hemoglobin on the 2,4-dinitrotoluene (2,4-DNT) dioxygenase activity of Burkholderia and on 2,4-DNT degradation in two-phase bioreactors.
Expression of vgb, encoding Vitreoscilla hemoglobin (VHb), in Burkholderia strain YV1 was previously shown to improve cell growth and enhance 2,4-dinitrotoluene (2,4-DNT) degradation compared with control strain DNT, especially under hypoxic conditions. In the work reported here, the ratio of 2,4-DNT degraded to oxygen uptake was approximately 5-fold larger for strain YV1 than for strain DNT. The addition of purified VHb to cytosolic fractions of strain DNT increased 2,4-DNT degradation 1.5-fold, compared with 1.1-fold for control bovine Hb, but increased the 2,4-DNT degradation 2.7-fold when added to partially purified 2,4-DNT dioxygenase, compared with 1.3-fold for bovine Hb. This suggests a direct transfer of oxygen from VHb to the oxygenase. In a bioreactor at high 2,4-DNT concentration (using 100 ml oleyl alcohol containing 2 g 2,4-DNT as the second phase) with 1.5 l culture, both strains could remove 0.8 g 2,4-DNT by 120 h; and, under the same conditions in a fed-batch reactor, the degradation increased to 1 g for strain YV1 but not for strain DNT.
Department of Biological, Chemical, and Physical Sciences, Illinois Institute of Technology, IL 60616, Chicago, USA.
Jui-Ming
JM
Lin
Benjamin C
BC
Stark
Dale A
DA
Webster
D001426:Bacterial Proteins / Q000494:pharmacology*; D001673:Biodegradation, Environmental; D019149:Bioreactors; D019117:Burkholderia / Q000187:drug effects / Q000201:enzymology*; D003600:Cytosol / Q000201:enzymology; D004789:Enzyme Activation / Q000187:drug effects; D005233:Fatty Alcohols / Q000494:pharmacology; D006454:Hemoglobins / Q000494:pharmacology*; D010100:Oxygen / Q000378:metabolism; D010105:Oxygenases / Q000302:isolation & purification / Q000378:metabolism*; D054793:Truncated Hemoglobins
D001426:Bacterial Proteins; D005233:Fatty Alcohols; D006454:Hemoglobins; D054793:Truncated Hemoglobins; C082613:hemoglobin protein, Vitreoscilla; C010268:oleyl alcohol; D010105:Oxygenases; C100896:2,4-dinitrotoluene dioxygenase; D010100:Oxygen