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Keywords:

  • biostimulation;
  • carvone;
  • cumene;
  • groundwater;
  • plant terpenes;
  • secondary plant metabolites;
  • TCE

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 μmol 1−1 of TCE and amended weekly for 16 weeks with 20 μl 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.