ABSTRACT
AIMS: To examine plant terpenoids as inducers of TCE (trichloroethylene) 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 micromol 1(-1) of TCE and amended weekly for 16 weeks with 20 microl 1(-1) of the following plant monoterpenes: linalool, pulegone, R-(+) carvone, S-(-) carvone, farnesol, cumene. Yeast extract-amended and unamended control treatments were also prepared. The addition of R-carvone 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 significantly enhanced through the addition of selected plant terpenoids. SIGNIFICANCE AND IMPACT OF THE STUDY: Plant terpenoid and nutrient supplementation to groundwater might provide an environmentally benign means of enhancing the rate of in situ TCE bioremediation.
