Accelerated Depletion of 2′,3,4 Pcb Congener Using Combinations of the Alfalfa Plant and Bacterial Species

We have studied 2′,3,4 PCB (polychlorinated biphenyl) degradation capability of two bacterial species with the alfalfa plant. These bacterial species, Commamonas sp. and Rhodococcus sp., were obtained from Dr. J. Tiedje (Michigan State University, East Lansing, MI). Five treatments were set up in duplicate and included an uninoculated control of sterile soil spiked with 100 ppm of 2′,3,4 PCB (pure congener) and autoclaved soil samples spiked with 100 ppm of 2′,3,4 PCB inoculated with Rhodococcus sp. or Commamonas sp. with and without alfalfa plants. Complete PCB depletion, measured by HPLC and GC-MS, was observed with both bacterial species after four weeks incubation period. The PCB depletion was proportional to the bacterial growth measured by CFUs count, indicating a possible use of the pollutant by these microorganisms as a source of carbon and energy. PCB depletion from the spiked soil was significantly accelerated by 50% on the second week and 100% by the third week when Commamonas sp. and Rhodococcus sp. were combined with alfalfa plants. Our study showed that concomitant use of microorganisms and plants could result in a tremendous quantitative improvement of in situ PCB cleanup from spiked soil in a time-saving manner.