Utilization of Microbial Biofilms as Monitors of Bioremediation

Abstract

A down-well aquifer microbial sampling system was developed using glass wool or Bio-Sep beads as a solidphase support matrix. Here we describe the use of these devices to monitor the groundwater microbial community dynamics during field bioremediation experiments at the U.S. Department of Energy Natural and Accelerated Bioremediation Research Program's Field Research Center at the Oak Ridge National Laboratory. During the 6-week deployment, microbial biofilms colonized glass wool and bead internal surfaces. Changes in viable biomass, community composition, metabolic status, and respiratory state were reflected in sampler composition, type of donor, and groundwater pH. Biofilms that formed on Bio-Sep beads had 2-13 times greater viable biomass; however, the bead communities were less metabolically active [higher cyclopropane/monoenoic phospholipid fatty acid (PLFA) ratios] and had a lower aerobic respiratory state (lower total respiratory quinone/ PLFA ratio and ubiquinone/menaquinone ratio) than the biofilms formed on glass wool. Anaerobic growth in these systems was characterized by plasmalogen phospholipids and was greater in the wells that received electron donor additions. Partial 16S rDNA sequences indicated that Geobacter and nitrate-reducing organisms were induced by the acetate, ethanol, or glucose additions. DNA and lipid biomarkers were extracted and recovered without the complications that commonly plague sediment samples due to the presence of clay or dissolved organic matter. Although microbial community composition in the groundwater or adjacent sediments may differ from those formed on down-well biofilm samplers, the metabolic activity responses of the biofilms to modifications in groundwater geochemistry record the responses of the microbial community to biostimulation while providing integrative sampling and ease of recovery for biomarker analysis.

Acyl-Homoserine Lactones Can Induce Virus Production in Lysogenic Bacteria: an Alternative Paradigm for Prophage Induction

“…To more accurately assess induction responses under soil conditions, we employed Bio-Sep beads as a novel in situ enrichment matrix. Given their high surface area and porosity, Bio-Sep beads mimic the soil environment and previously have been used in many environmental applications as a cell immobilization matrix and to sample and characterize microbial communities from various environments (14,37). We recently used them to assess the prevalence of lysogeny within soil bacterial communities (19).…”

Functional Diversity and Electron Donor Dependence of Microbial Populations Capable of U(VI) Reduction in Radionuclide-Contaminated Subsurface Sediments

“…Environmental clone sequences closely related to members of the Deltaproteobacteria were shown to increase after biostimulation of the ORFRC subsurface with glucose or ethanol (24,48,51). The detection of Proteobacteria, Actinobacteria, and Firmicutes taxa in cultivation-independent studies in groundwater and sediments at the ORFRC (2,24,44,48,49,51,68,69) led previous groups to infer their physiological role in bioremediation. By coupling geochemical analysis with community characterization, we provide further evidence that these taxa are active during bioremediation and are likely involved in nitrate, U(VI), and Fe(III) reduction.…”

Distribution of Microbial Biomass and Potential for Anaerobic Respiration in Hanford Site 300 Area Subsurface Sediment

“…Subsamples frozen at Ϫ80°C were shipped overnight to Microbial Insights, Inc., for analysis of phospholipid fatty acids (PLFA). Phospholipid biomarker analysis was performed as previously described (40). Briefly, PLFA were extracted with a single-phase chloroformmethanol buffer system (54).…”