Cytotoxicity associated with trichloroethylene oxidation in Burkholderia cepacia G4

Citation
Cm. Yeager et al., Cytotoxicity associated with trichloroethylene oxidation in Burkholderia cepacia G4, APPL ENVIR, 67(5), 2001, pp. 2107-2115
Citations number
54
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Biology,Microbiology
Journal title
APPLIED AND ENVIRONMENTAL MICROBIOLOGY
ISSN journal
0099-2240 → ACNP
Volume
67
Issue
5
Year of publication
2001
Pages
2107 - 2115
Database
ISI
SICI code
0099-2240(200105)67:5<2107:CAWTOI>2.0.ZU;2-4
Abstract
The effects of trichloroethylene (TCE) oxidation on toluene 2-monooxygenase activity, general respiratory activity, and cell culturability mere examin ed in the toluene-oxidizing bacterium Burkholderia cepacia G4. Nonspecific damage outpaced inactivation of toluene 2-monooxygenase in B. cepacia G4 ce lls. Cells that had degraded approximately 0.5 mu mol of TCE (mg of cells(- 1)) lost 95% of their acetate-dependent O-2 uptake activity (a measure of g eneral respiratory activity), yet toluene-dependent O-2 uptake activity dec reased only 35%. Cell culturability also decreased upon TCE oxidation; howe ver, the extent of loss varied greatly (up to 3 orders of magnitude) with t he method of assessment. Addition of catalase or sodium pyruvate to the sur faces of agar plates increased enumeration of TCE-injured cells by as much as 100-fold, indicating that the TCE injured cells were ultrasensitive to o xidative stress. Cell suspensions that had oxidized TCE recovered the abili ty to grow in liquid minimal medium containing lactate or phenol, but recov ery was delayed substantially when TCE degradation approached 0.5 mu mol (m g of cells(-1)) or 66% of the cells' transformation capacity for TCE at the cell density utilized, Furthermore, among B. cepacia G4 cells isolated on Luria-Bertani agar plates from cultures that had degraded approximately 0.5 mu mol of TCE (mg of cells(-1)), up to 90% mere Tol(-) variants, no longer capable of TCE degradation. These results indicate that a toxicity thresho ld for TCE oxidation exists in B. cepacia G4 and that once a cell suspensio n has exceeded this toxicity threshold, the likelihood of reestablishing an active, TCE-degrading biomass from the cells will decrease significantly.