| 20348302 |
Yagi JM, Suflita JM, Gieg LM, Derito CM, Jeon CO, Madsen EL: Subsurface cycling of nitrogen and anaerobic aromatic hydrocarbon biodegradation shown by nucleic acid and metabolic biomarkers. Appl Environ Microbiol. 2010 Mar 26.
Microbial processes are crucial for ecosystem maintenance, yet their documentation in complex open field sites is challenging. Here we used a multidisciplinary strategy (site geochemistry, laboratory biodegradation assays, and field extraction of molecular biomarkers) to deduce an ongoing linkage between aromatic hydrocarbon biodegradation and nitrogen cycling in a contaminated subsurface site. Three site wells were monitored over 10 months, showing fluctuating concentrations of nitrate, ammonia, sulfate, sulfide, methane, and other constituents. Biodegradation assays under multiple redox conditions indicated that naphthalene metabolism was favored under aerobic conditions. To explore in situ field processes, we measured metabolites of anaerobic naphthalene metabolism and expressed mRNA transcripts selected to document aerobic and anaerobic microbial transformations of ammonia, nitrate, and methylated aromatic contaminants. GC/MS detection of two carboxylated naphthalene metabolites and transcribed benzylsuccinate synthase, cytochrome c nitrite reductase, and ammonia monooxygenase genes indicated that anaerobic metabolism of aromatic compounds and that both dissimilatory nitrate reduction to ammonia (DNRA) and nitrification were in progress in situ. These data link formation (via DNRA) and destruction (via nitrification) of ammonia to achieve in situ cycling of nitrogen in this subsurface habitat where metabolism of aromatic pollutants has led to the accumulation of reduced metabolic end products (e.g., ammonia and methane). |
81(1,1,1,1) |