Open AccessInteractions of earthworms with indigenous and bioaugmented PCB‐degrading bacteria
Author(s) -
Luepromchai Ekawan,
Singer Andrew C.,
Yang ChingHong,
Crowley David E.
Publication year - 2002
Publication title -
fems microbiology ecology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.377
H-Index - 155
eISSN - 1574-6941
pISSN - 0168-6496
DOI - 10.1111/j.1574-6941.2002.tb00980.x
Subject(s) - biology , bacteria , indigenous , earthworm , ecology , bioaugmentation , microbiology and biotechnology , oligochaeta (plant) , microorganism , genetics
Partial bioremediation of polychlorinated biphenyl (PCB)‐contaminated soils has been achieved using bioaugmentation with PCB‐degrading bacteria and earthworms. To further study the contribution of earthworms to bioremediation, an experiment was conducted in which the changes in indigenous and bioaugmented PCB‐degrading bacteria were analyzed during treatment of contaminated soil using earthworms ( Pheretima hawayana ) alone or in combination with the PCB‐degrading bacteria, Ralstonia eutrophus and Rhodococcus sp. ACS. Bacteria used for bioaugmentation were induced with carvone and salicylic acid in culture and were repeatedly applied every 3–4 days to the surface of unmixed, 20‐cm long soil columns containing 100 ppm Aroclor 1242. After 9 weeks of treatment, the soil bacterial communities were analyzed using PCR primers for the bph genes. Results showed that approximately 50% of the PCBs were removed in the top 9 cm using a combination of earthworms and bioaugmentation, whereas bioaugmentation or earthworms applied alone were effective only for removing PCBs from the top 3 cm of the soil columns. Enhanced removal of PCBs caused by earthworms was associated with an increase in the population size of culturable, indigenous biphenyl‐degrading bacteria, and an increase in the level of the bphA and bphC genes. The results suggest that earthworms facilitate PCB bioremediation by enhancing the dispersal of PCB‐degrading bacteria in bioaugmented columns, as well as providing environmental conditions that favor the growth and activity of indigenous PCB‐degrading bacteria.