Open AccessDenitrification associated with Groups I and II methanotrophs in a gradient enrichment system
Author(s) -
Amaral J.A.,
Archambault C.,
Richards S.R.,
Knowles R.
Publication year - 1995
Publication title -
fems microbiology ecology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.377
H-Index - 155
eISSN - 1574-6941
pISSN - 0168-6496
DOI - 10.1111/j.1574-6941.1995.tb00185.x
Subject(s) - denitrifying bacteria , biology , denitrification , methanotroph , environmental chemistry , anaerobic oxidation of methane , water column , terminal restriction fragment length polymorphism , nitrogen , methane , ecology , biochemistry , chemistry , restriction fragment length polymorphism , polymerase chain reaction , organic chemistry , gene
The occurrence and distribution of Groups I and II methanotrophs and their potential impact on denitrification were studied in a diffusion column model system simulating CH 4 and O 2 sources and delivery in the environment. We used NO 3 − ‐ or NH 4 + ‐containing mineral salts media and three different inoculum sources: a swamp soil, a lake sediment and a cultivated humisol. The methylotrophic community structure which developed in the diffusion columns was characterized using oligodeoxynucleotide probes specific for ribulose monophosphate pathway (Group I; 10γ probe) and serine pathway (Group II; 9α probe) methylotrophs. Methanotrophs that grew near the top of the columns in zones of low CH 4 and high O 2 concentration, were generally from Group I; those growing at the bottom of the columns in zones of high CH 4 and low O 2 concentration were from Group II. Only in the humisol were both Group I and II detected at the top of the column. Concomitant production of N 2 O with CH 4 consumption, observed in the diffusion columns, was confirmed in enrichment cultures. At least three denitrifiers associated with methanotrophic growth and activity were isolated. Methanotrophs that grew under high CH 4 and low O 2 conditions were associated with a Hyphomicrobium ‐like bacterium capable of denitrifying with methanol. Methanotrophic activity supported denitrification by (i) reducing the O 2 tension, and (ii) supplying organic compounds to the denitrifiers. Because this model system mimics many of the natural environments of methanotrophs, it is likely that the observed segregation of physiological types of methanotrophs and their interaction with denitrifiers also occur in nature.