The relative contribution of methanotrophs to microbial communities and carbon cycling in soil overlying a coal-bed methane seep

Abstract

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.

The value of soil respiration measurements for interpreting and modeling terrestrial carbon cycling

“…The general assumption in most soil flux studies is that only biological communities near the soil surface are responsible for the observed CO 2 . This is of course a simplification, and CO 2 in the soil profile may originate from a variety of sources, including soil pedogenic or liquid water carbonates (Cerling et al 1991;Serrano-Ortiz et al 2010;Shanhun et al 2012;Risk et al 2013b), methane oxidation (Romanak et al 2012;Mills et al 2013), or volcanic activity (Werner and Brantley 2003;Viveiros et al 2008;Beulig et al 2016). Soil sinks for CO 2 may also exist, for example from carbonate dissolution (Shanhun et al 2012) and C-fixation by chemoautotrophic microbes (Beulig et al 2016).…”

Peat Properties, Dominant Vegetation Type and Microbial Community Structure in a Tropical Peatland

“…(e) PCA scores for PLFA biomarkers. Means ± one SE (n = 5) methanotrophs, and C18:1ω7c and C18:1ω8c for type II methanotrophs (Maxfield et al 2006;Mills et al 2013;Roslev and Iversen 1999;Singh et al 2007). Both C16:1ω5 and C18:1ω7c were detected in both C. panamensis and R. taedigera peats in this study and were the most abundant Gram negative biomarkers, accounting for approximately 73% (21.2 μg g −1 ) of total Gram negative PLFA abundance (Fig.…”

Legacy effects override soil properties for CO2 and N2O but not CH4 emissions following digestate application to soil

“…Soil CH 4 flux can be highly variable because methane microbial production and consumption can simultaneously occur in the soil within different microsites. CH 4 is generally consumed in aerated soil, such as upland soils, when methanotrophic bacteria oxidize CH 4 to CO 2 while concurrently assimilating a large proportion of CH 4 ‐C, often as much as half or more, into microbial biomass C (Mills et al, 2013). Conversely methanogenesis is an anaerobic process.…”