PCE dechlorination by non-Dehalococcoides in a microbial electrochemical system

Area of Science:

• Environmental Microbiology
• Bioremediation Engineering
• Electrochemistry

Background:

• Bioremediation of tetrachloroethene (PCE) often relies on organic substrates, which can cause undesirable microbial proliferation.
• This microbial growth can lead to biofouling in subsurface environments, hindering remediation efforts.

Purpose of the Study:

• To investigate the efficacy of a microbial electrochemical system (MES) for PCE dechlorination.
• To identify the bacterial communities involved in PCE dechlorination within the MES, utilizing electrodes as the electron donor.

Main Methods:

• PCE dechlorination was conducted in a microbial electrochemical system (MES) with a cathode polarized at -500 mV vs. SHE as the electron donor.
• Bacterial community analysis was performed using denaturing gel gradient electrophoresis and pyrosequencing.

Main Results:

• A diverse range of non-Dehalococcoides bacteria, including Acinetobacter sp., Rhodopseudomonas sp., Pseudomonas aeruginosa, and Enterobacter sp., were found to be dominant.
• These identified bacteria demonstrated capabilities in electron transfer, hydrogen production, and dechlorination.
• The Dehalococcoides group, typically associated with reductive dechlorination, was not detected in this MES.

Conclusions:

• Bacterial species beyond the Dehalococcoides genus can effectively mediate microbial electrochemical dechlorination.
• This finding suggests a potential for developing innovative bioremediation technologies using non-Dehalococcoides bacteria in MES.
• The use of electrodes as electron donors circumvents issues associated with organic substrate-induced microbial overgrowth.