The relative contribution of methanotrophs to microbial communities and carbon cycling in soil overlying a coal-bed methane seep.
Seepage of coal-bed methane (CBM) through soils is a potential source of atmospheric CH4 and also a likely source of ancient (i.e. (14) C-dead) carbon to soil microbial communities. Natural abundance (13) C and (14) C compositions of bacterial membrane phospholipid fatty acids (PLFAs) and soil gas CO2 and CH4 were used to assess the incorporation of CBM-derived carbon into methanotrophs and other members of the soil microbial community. Concentrations of type I and type II methanotroph PLFA biomarkers (16:1ω8c and 18:1ω8c, respectively) were elevated in CBM-impacted soils compared with a control site. Comparison of PLFA and 16s rDNA data suggested type I and II methanotroph populations were well estimated and overestimated by their PLFA biomarkers, respectively. The δ(13) C values of PLFAs common in type I and II methanotrophs were as negative as -67‰ and consistent with the assimilation of CBM. PLFAs more indicative of nonmethanotrophic bacteria had δ(13) C values that were intermediate indicating assimilation of both plant- and CBM-derived carbon. Δ(14) C values of select PLFAs (-351 to -936‰) indicated similar patterns of CBM assimilation by methanotrophs and nonmethanotrophs and were used to estimate that 35-91% of carbon assimilated by nonmethanotrophs was derived from CBM depending on time of sampling and soil depth.
Department of Chemistry and Geochemistry, Colorado School of Mines, Golden, CO, USA.
Christopher T
CT
Mills
Gregory F
GF
Slater
Robert F
RF
Dias
Stephanie A
SA
Carr
Christopher M
CM
Reddy
Raleigh
R
Schmidt
Kevin W
KW
Mandernack
D020561:Alphaproteobacteria / Q000737:chemistry / Q000145:classification / Q000254:growth & development / Q000378:metabolism*; D001419:Bacteria / Q000378:metabolism; D002244:Carbon / Q000378:metabolism; D057486:Carbon Cycle; D002245:Carbon Dioxide / Q000378:metabolism; D002247:Carbon Isotopes / Q000378:metabolism; D003031:Coal; D004269:DNA, Bacterial / Q000032:analysis; D004275:DNA, Ribosomal / Q000032:analysis; D005227:Fatty Acids / Q000032:analysis; D020563:Gammaproteobacteria / Q000737:chemistry / Q000145:classification / Q000254:growth & development / Q000378:metabolism*; D008697:Methane / Q000032:analysis / Q000378:metabolism*; D042083:Methylocystaceae / Q000145:classification / Q000254:growth & development / Q000378:metabolism; D010743:Phospholipids / Q000032:analysis; D012987:Soil / Q000737:chemistry; D012988:Soil Microbiology
D002247:Carbon Isotopes; D003031:Coal; D004269:DNA, Bacterial; D004275:DNA, Ribosomal; D005227:Fatty Acids; D010743:Phospholipids; D012987:Soil; D002245:Carbon Dioxide; D002244:Carbon; D008697:Methane