Enhanced biotransformation of TCE using plant terpenoids in contaminated groundwater

Aims: To examine plant terpenoids as inducers of TCE biotransformation by an indigenous microbial community originating from a plume of TCE-contaminated groundwater.

Methods and Results: One-litre microcosms of groundwater were spiked with 100 mol 1-1 of TCE and amended weekly for 16 weeks with 20 l 1-1 of the following plant monoterpenes: linalool, pulegone, R- (+)-carvone, S- (-)carvone, farnesol, cumene. Yeast extract- and un-amended control treatments were also prepared. The addition of R- and S-carvone, linalool and cumene resulted in the biotransformation of upwards of 88 % of the TCE, significantly more than the unamendment control (61 %). The aforementioned group of terpenes also significantly (P < 0.05) allowed more TCE to be degraded than the remaining two terpenes (farnesol and pulegone) and the yeast extract treatment which biotransformed 74-75 % of the TCE. The microbial community profile was monitored by denaturing gradient gel electrophoresis and demonstrated much greater similarities between the microbial communities in terpene-amended treatments than in the yeast extract or unamended controls.

Conclusions: TCE biotransformation can be signficantly enhanced through the addition of selected plant terpenoids.

Significance and Impact of Study: Plant terpenoid and nutrient supplementation to groundwater might provide an environmentally benign means of enhancing the rate of in situ TCE bioremediation.