Bacterial Strain Improvement for Bioremediation.
Final rept. 1 May 95-31 Mar 98,
ILLINOIS INST OF TECH CHICAGO
Pagination or Media Count:
The gene vgb for the bacterial hemoglobin from Vitreoscilla has been cloned in Burkholderia strain DNT which can degrade 2,4-dinitrotoluene DNT. The new strain,I YVl, expressed vgb, grew better, survived longer, and degraded DNT faster than - strain DNT. The addition of surfactants and succinate or yeast extract also stimulated DNT degradation up to 99.5. Measurements of the oxygen kinetics for DNT degradation showed that for all strains the kinetics of oxygen uptake were bip- hasic but could be resolved into two components. Purified VHb added to cell-free extracts of strain DNT stimulated DNT degradation, but not control bovine Rb. Regarding biodegradation of DNT in a soil slurry spiked with DNT, YVl showed a slightly higher degradation rate ranging from 5 to 18. When vgb was cloned into E.coli containing the gene for DNT dioxygenase the resultant strain exhibited - enhanced growth, viability, and degraded twice as much DNT under low aeration condi- tions. DNT dioxygenase has been partially purified by gel chromatography it requir. NADIl, is stimulated by phospholipids, and inhibited at high ionic strength. Probin the oxygen binding site of VHb using site-directed mutagenesis showedthat the residue GlnE7 was not involved in stabilizing the bound oxygen.