Trichloroethylene degradation by methane-oxidizing cultures grown with various nitrogen sources Academic Article uri icon


  • Methaneoxidizing microorganisms exhibit great potential for vadose zone bioremediation since they grow on a gaseous substrate, are capable of cometabolically degrading a wide range of common subsurface contaminants, and fix molecular nitrogen as a nitrogen source. This paper reports the effects of supplying nitrogen as nitrate, ammonia, and molecular nitrogen on the growth, trichloroethylene (TCE) degradation capacity, and energy storage capacity of a mixed methaneoxidizing culture. Cells inoculated from a nitratesupplied methaneoxidizing culture grew fastest while fixing atmospheric nitrogen when oxygen partial pressures were kept less than 8%. Cell growth and methane oxidation were more rapid for ammoniasupplied cells than for nitratesupplied or nitrogenfixing cells. However, nitrogenfixing cells were capable of oxidizing TCE as efficiently as nitrate or ammoniasupplied cells, and they exhibited the highest TCE transformation capacity of all three cultures both with and without formate as an exogenous reducing energy source. The TCE product toxicity was not as pronounced for the nitrogenfixing cells as for the nitrate or ammoniasupplied cells after exposure to high (20 mg/L) or low (2 mg/L) TCE concentrations. Energy storage in the form of polyhydroxybutyrate was 20% to 30% higher for nitrogenfixing cells; increased energy storage may be responsible for the higher transformation capacity of nitrogenfixing cells when no external reducing energy was available. However, because nitrogenfixing cells also exhibited the highest transformation capacity in the presence of formate, their cometabolic activity was enhanced beyond that which can be explained by increased energy storage alone.

published proceedings


author list (cited authors)

  • Chu, K. H., & Alvarez-Cohen, L.

citation count

  • 48

complete list of authors

  • Chu, KH||Alvarez-Cohen, L

publication date

  • January 1996