Changes of the carbon isotopic composition of trichloroethylene during aerobic biodegradation: a new tool to estimate removal efficiencies

Trichloroethylene (TCE) was degraded aerobically with the strain Burkholderia cepacia G4. The degradation leveled out after ~ 40 hours, while the removal efficiency depended on the optical cell density (OD540). During the experiment at an OD540 of 0.8, TCE was degraded up to 59.3 %, with an isotopic difference between initial and remaining substrate of 12.3 ‰. At a lower OD540 of 0.5 the amount of TCE degraded was only 40.5 % and the δ13CTCE difference between initial and remaining substrate was 10.5 ‰. Trichloroethylene (TCE) was degraded aerobically with the strain Burkholderia cepacia G4. The degradation leveled out after ~ 40 hours, while the removal efficiency depended on the optical cell density. TCE can be degraded aerobically by a co-metabolic process that requires phenol as a primary substrate. This generates the enzyme toluene-orhto mono-oxygenase, which is necessary for TCE degradation. The cometabolic aerobic TCE degradation seems to be limited by the availability of the necessary toluene mono-oxygenase enzyme. The comparison of the isotope ratios between initial and remaining TCE is a valuable tool to estimate process efficiencies. This is confirmed by the smaller isotope fractionations at lower cell densities.