Biotransformations and Bioremediation
Laboratory and field studies have demonstrated a link between the presence of Dehalococcoides and complete dechlorination of PCE and TCE to ethene. The electron acceptors for Dehalococcoides are halogenated compounds, the electron donor is H2, and their carbon source is acetate. They are obligate anaerobes that grow optimally at a near-neutral pH, and vitamin B12 is an essential cofactor for their reductive dehalogenases. The reductive dechlorination rates of the chlorinated compounds decrease significantly when these microorganisms are not part of a microbial consortium suggesting that they require yet-unidentified growth factors supplied by other members in the community. Our current and future efforts for enhancing reductive dehalogenation processes focus on optimizing carbon, electron, and corrinoid flows by better understanding microbial interactions and reducing losses of electrons to electron sinks, such as methane, and by exploiting the capability of acetogens to produce corrinoids needed by Dehalococcoides. Better understanding of these microbial interactions will allow us to predict and improve bioremediation outcomes, as well as make fundamental contributions towards the microbial ecology of dechlorinating communities.
Collaborators: Prathap Parameswaran, Sudeep Popat, Dae-Wook Kang, César Torres, Bruce Rittmann, Rolf Halden
Funding: National Science Foundation (NSF) CAREER, ASU Rising Star Program
Publications on this Topic
Membrane Biofilm Reactors (mbfrs)
The Membrane Biofilm Reactor (MBfR) connects engineering with nature. Microorganisms are well known for using pollutants as their energy source, and then biotransforming hazardous chemicals into safer substances. However, in many cases, those biotransformations must be facilitated to become true. In the MBfR, we provide an engineered environment for microorganisms to perform the biotransformation of several water pollutants such as nitrate, perchlorate, selenate, among others. The MBfR uses novel materials, i.e., hollow-membranes, which deliver hydrogen gas to “spark” the biotransformation and also serve as a substratum for developing biofilm communities. Our on-going efforts are focused on understanding the microbial interactions among members of the biofilm. We aim to suppress detrimental microbial relationships and to enhance beneficial partnerships among members of the community.