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Title: Effect of nitrogen source on growth and trichloroethylene degradation by methane-oxidizing bacteria.

Authors: Chu, K H; Alvarez-Cohen, L

Published In Appl Environ Microbiol, (1998 Sep)

Abstract: The effect of nitrogen source on methane-oxidizing bacteria with respect to cellular growth and trichloroethylene (TCE) degradation ability were examined. One mixed chemostat culture and two pure type II methane-oxidizing strains, Methylosinus trichosporium OB3b and strain CAC-2, which was isolated from the chemostat culture, were used in this study. All cultures were able to grow with each of three different nitrogen sources: ammonia, nitrate, and molecular nitrogen. Both M. trichosporium OB3b and strain CAC-2 showed slightly lower net cellular growth rates and cell yields but exhibited higher methane uptake rates, levels of poly-beta-hydroxybutyrate (PHB) production, and naphthalene oxidation rates when grown under nitrogen-fixing conditions. The TCE-degrading ability of each culture was measured in terms of initial TCE oxidation rates and TCE transformation capacities (mass of TCE degraded/biomass inactivated), measured both with and without external energy sources. Higher initial TCE oxidation rates and TCE transformation capacities were observed in nitrogen-fixing mixed, M. trichosporium OB3b, and CAC-2 cultures than in nitrate- or ammonia-supplied cells. TCE transformation capacities were found to correlate with cellular PHB content in all three cultures. The results of this study suggest that the nitrogen-fixing capabilities of methane-oxidizing bacteria can be used to select for high-activity TCE degraders for the enhancement of bioremediation in fixed-nitrogen-limited environments.

PubMed ID: 9726896 Exiting the NIEHS site

MeSH Terms: Ammonia/metabolism; Biodegradation, Environmental; Hydroxybutyrates/analysis; Methane/metabolism*; Methylococcaceae/growth & development*; Methylococcaceae/metabolism*; Molecular Sequence Data; Nitrates/metabolism; Nitrogen/metabolism*; Nitrogenase/metabolism; Oxidation-Reduction; Polyesters/analysis; Trichloroethylene/metabolism*

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