Open AccessAmmonia cometabolism and product inhibition vary considerably among species of methanotrophic bacteria
Author(s) -
Nyerges Györgyi,
Stein Lisa Y.
Publication year - 2009
Publication title -
fems microbiology letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.899
H-Index - 151
eISSN - 1574-6968
pISSN - 0378-1097
DOI - 10.1111/j.1574-6968.2009.01674.x
Subject(s) - hydroxylamine , nitrite , chemistry , ammonia monooxygenase , ammonia , ammonium , environmental chemistry , gammaproteobacteria , nitrification , anaerobic oxidation of methane , inorganic chemistry , nitrate , biochemistry , methane , nitrogen , organic chemistry , 16s ribosomal rna , gene
Ecological studies have indicated that relative abundances of Gammaproteobacteria methanotrophs (Gamma‐MOB) vs. Alphaproteobacteria methanotrophs (Alpha‐MOB) in nitrogen (N) impacted soils are dictated in part by their abilities to tolerate inhibitory effects of ammonium and nitrite. In particular, ammonia is a cometabolic substrate and competitive inhibitor of methane monooxygenase. The rates of ammonia and hydroxylamine oxidation and inhibition of methane‐oxidizing activity by ammonium and nitrite were compared among two Gamma‐MOB and two Alpha‐MOB to determine whether methanotrophs of the same class shared similar physiological profiles. Each isolate exhibited unique K m(app) for ammonia and V max for nitrite production with or without reductant (methane or sodium formate). The rates of nitrite production from hydroxylamine followed similar trends to rates of ammonia oxidation, indicating that hydroxylamine‐oxidizing enzymes were central participants in the ammonia‐oxidizing pathway. Methylomonas methanica was incapable of either ammonia or hydroxylamine oxidation. A broad range of sensitivities to ammonium and nitrite inhibition were measured with little consistency between isolates of the same class. The results indicate that physiological responses, and perhaps environmental adaptations, to N compounds are organism specific for methanotrophs.