Methane Oxidation and Molecular Characterization of Methanotrophs from a Former Mercury Mine Impoundment.
The Herman Pit, once a mercury mine, is an impoundment located in an active geothermal area. Its acidic waters are permeated by hundreds of gas seeps. One seep was sampled and found to be composed of mostly CO₂ with some CH₄ present. The δ(13)CH₄ value suggested a complex origin for the methane: i.e., a thermogenic component plus a biological methanogenic portion. The relatively (12)C-enriched CO₂ suggested a reworking of the ebullitive methane by methanotrophic bacteria. Therefore, we tested bottom sediments for their ability to consume methane by conducting aerobic incubations of slurried materials. Methane was removed from the headspace of live slurries, and subsequent additions of methane resulted in faster removal rates. This activity could be transferred to an artificial, acidic medium, indicating the presence of acidophilic or acid-tolerant methanotrophs, the latter reinforced by the observation of maximum activity at pH = 4.5 with incubated slurries. A successful extraction of sterol and hopanoid lipids characteristic of methanotrophs was achieved, and their abundances greatly increased with increased sediment methane consumption. DNA extracted from methane-oxidizing enrichment cultures was amplified and sequenced for pmoA genes that aligned with methanotrophic members of the Gammaproteobacteria. An enrichment culture was established that grew in an acidic (pH 4.5) medium via methane oxidation.
Geological Survey, Menlo Park, CA 94025, USA. sbaesman@usgs.gov.
Shaun M
SM
Baesman
Geological Survey, Menlo Park, CA 94025, USA. lgmiller@usgs.gov.
Laurence G
LG
Miller
Department of Earth System Science, Stanford University, Stanford, CA 94305, USA. jhwei@stanford.edu.
Jeremy H
JH
Wei
Department of Earth System Science, Stanford University, Stanford, CA 94305, USA. yicho@stanford.edu.
Yirang
Y
Cho
Department of Earth, Atmospheric, and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, MA 02139, USA. ematys@mit.edu.
Emily D
ED
Matys
Department of Earth, Atmospheric, and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, MA 02139, USA. rsummons@mit.edu.
Roger E
RE
Summons
Department of Earth System Science, Stanford University, Stanford, CA 94305, USA. welander@stanford.edu.
Paula V
PV
Welander
Geological Survey, Menlo Park, CA 94025, USA. roremlan@usgs.gov.
Ronald S
RS
Oremland
acid mine drainage; hopanoids; methane stable isotopes; methanotrophic bacteria; sterols
Nature. 1972 Jun 30;237(5357):518
12635206
Nature. 2007 Dec 6;450(7171):874-8
18004305
Mol Syst Biol. 2011 Oct 11;7:539
21988835
Z Allg Mikrobiol. 1982;22(2):139-48
6806998
J Bacteriol. 1959 May;77(5):642-7
13654231
Mol Biol Evol. 1987 Jul;4(4):406-25
3447015
FEMS Microbiol Lett. 1995 Oct 15;132(3):203-8
7590173
Int J Syst Bacteriol. 1991 Apr;41(2):324-5
1854644
Appl Environ Microbiol. 2005 Oct;71(10):6458-62
16204580
Anal Chem. 2002 May 1;74(9):2003-7
12033299
FEMS Microbiol Lett. 2011 Nov;324(2):106-10
22092810
Appl Environ Microbiol. 2014 Nov;80(21):6782-91
25172849
Nature. 2006 Sep 7;443(7107):71-5
16957728
Geobiology. 2012 Mar;10(2):163-77
22221333
Microbiol Rev. 1996 Jun;60(2):439-71
8801441
J Gen Microbiol. 1970 May;61(2):205-18
5476891
Int J Syst Evol Microbiol. 2004 Nov;54(Pt 6):1919-20
15545410
Mikrobiologiia. 2012 Sep-Oct;81(5):656-64
23234077
Mol Biol Evol. 2013 Dec;30(12):2725-9
24132122
J Bacteriol. 2005 Jul;187(13):4303-5
15968038
J Bacteriol. 2005 Jul;187(13):4665-70
15968078
Appl Environ Microbiol. 2013 Oct;79(19):5918-26
23872554
J Chromatogr A. 2001 Jul 6;921(2):175-85
11471801
Environ Microbiol. 2014 Jan;16(1):255-64
24034209
Appl Environ Microbiol. 1995 Jul;61(7):2745-53
16535081
Proc Natl Acad Sci U S A. 2012 Aug 7;109(32):12905-10
22826256
J Bacteriol. 2009 Oct;191(19):6145-56
19592593
Extremophiles. 2014 Mar;18(2):207-18
24343375
Nature. 2007 Dec 6;450(7171):879-82
18004300
Appl Environ Microbiol. 1991 Jan;57(1):130-7
16348388
Appl Environ Microbiol. 2011 Dec;77(24):8509-15
21984248
Appl Environ Microbiol. 1983 May;45(5):1519-25
16346289
Int J Syst Evol Microbiol. 2003 Sep;53(Pt 5):1231-9
13130000
J Gen Microbiol. 1970 May;61(2):227-32
5476893
Appl Environ Microbiol. 2011 Aug 15;77(16):5643-54
21724892
ISME J. 2014 Sep;8(9):1945-8
24785289
Nucleic Acids Res. 1997 Sep 1;25(17):3389-402
9254694
J Gen Microbiol. 1970 May;61(2):219-26
5476892
Annu Rev Microbiol. 1970;24:135-58
4929654
Rapid Commun Mass Spectrom. 2003;17(24):2788-96
14673828