Inducible Surface Hydrophobicity of Microbial Consortia for Biofilm Remediation

Microbial degradation is an effective method of decontaminating pools of free-phase pollutants, such as chlorinated solvents and explosives, in groundwater. The formation of microbial consortia capable of residing on free-phase contaminants has been shownrecently by the proposer. The population obtained in a continuous selection process exhibited increased surface hydrophobicity, considered to be a key feature for anchoring the biofilm at the interface. The consortia effectively prevented the flux ofcontaminants into the water layer. After establishing a mature biofilm, the TCE concentration was reduced by 95 percent.The successful deployment of biofilm making organisms requires that their surface hydrophobicity be inducible upon contact with the free-phase substrate, insuring that the organisms will not aggregate and phase separate in aqueous ground flow. Anotherimportant feature of the organisms would be their capability to self-destruct after the pollutant was completely degraded. A research effort is proposed to enable the microbial degraders to have the following capabilities:inducible hydrophobicity of cell surface using continuous culture selection and self-destruction of consortia via incorporation of cassettes of suicide plasmids.The objective of the program is to develop microbial consortia that will effectively migrate to, anchor on, localize, and degrade pools of free-phase pollutants. (P-030454) In situ biological remediation is preferred to ex situ treatment because of lower energy and capital investment costs, it is more efficient due to immediate localization of the polluted area, and the aquifers can be completely restored.This development, if successful, will provide a unique opportunity for removing the source of extensive environmental contamination, namely pools of chlorinated solvents and solid residues of explosives. This process can be used not only by the USDepartment of Defense, but also by commercial firms both in the United States and abroad.