Biofilms characteristic of aquifer conditions can be rapidly and efficiently collected using in situ microcosms or “bio-traps” containing Bio-Sep® beads. Bio-Sep® beads are 3-4 mm in diameter and composed of 25% aramid polymer and 75% powdered activated carbon (PAC). When bio-traps are deployed in groundwater, indigenous bacteria enter through the outside membrane and migrate into the porous internal matrix. Microbes then attach to this internal structure and reproduces to form biofilms. In this manner, microbes can be concentrated for analysis despite their relatively low density of microbes in the sampled groundwater.

Bio-Sep beads can also be “baited” with a variety of organic compounds by vapor phase adsorption onto the PAC component of the beads. The adsorbed organics have been shown to be bioavailable to bacteria that form biofilms in the beads during incubation in a contaminated aquifer. If the compound is labeled with 13C, polar lipids may be extracted from bead biofilms and the derived fatty acid methyl esters (FAMEs) analyzed for 13C incorporation using GC-IRMS. Since the beads are clean of biomarkers and sterile when deployed, incorporation of 13C in phospholipids provides proof of in situ biodegradation of a target compound by indigenous microorganisms under actual aquifer conditions. Further proof biodegradation is obtained from 13C analysis of residual carbon dioxide in the beads post-incubation. Case studies investigating in situ biodegradation of BTEX components and naphthalene are provided.

Primary Author/Conference Presenter:
Kerry L. Sublette
The University of Tulsa
Tulsa, Oklahoma

Katherine Clark, Dora Taggart, Anita Biernacki, Brett R. Baldwin; Microbial Insights, Inc., Knoxville, TN