Activity and diversity of methane-oxidizing bacteria in glacier forefields on siliceous and calcareous bedrock

作者：Nauer P A; Dam B; Liesack W; Zeyer J; Schroth M H^*

来源：Biogeosciences, 2012, 9(6): 2259-2274.

DOI：10.5194/bg-9-2259-2012

The global methane (CH4) cycle is largely driven by methanogenic archaea and methane-oxidizing bacteria (MOB), but little is known about their activity and diversity in pioneer ecosystems. We conducted a field survey in fore-fields of 13 receding Swiss glaciers on both siliceous and calcareous bedrock to investigate and quantify CH4 turnover based on soil-gas CH4 concentration profiles, and to characterize the MOB community by sequencing and terminal restriction fragment length polymorphism (T-RFLP) analysis of pmoA. Methane turnover was fundamentally different in the two bedrock categories. Of the 36 CH4 concentration profiles from siliceous locations, 11 showed atmospheric CH4 consumption at concentrations of similar to 1-2 mu L L-1 with soil-atmosphere CH4 fluxes of -0.14 to -1.1 mg m(-2) d(-1). Another 11 profiles showed no apparent activity, while the remaining 1(4) exhibited slightly increased CH4 concentrations of similar to 2-10 mu L L-1, most likely due to microsite methanogenesis. In contrast, all profiles from calcareous sites suggested a substantial, yet unknown CH4 source below our sampling zone, with soil-gas CH4 concentrations reaching up to 1400 mu L L-1. Remarkably, most soils oxidized similar to 90% of the deep-soil CH4, resulting in soil-atmosphere fluxes of 0.12 to 31 mg m(-2) d(-1). MOB showed limited diversity in both siliceous and calcareous forefields: all identified pmoA sequences formed only 5 operational taxonomic units (OTUs) at the species level and, with one exception, could be assigned to either Methylocystis or the as-yet-uncultivated Upland Soil Cluster gamma (USC gamma). The latter dominated T-RFLP patterns of all siliceous and most calcareous samples, while Methylocystis dominated in 4 calcareous samples. Members of Upland Soil Cluster gamma (USC gamma) were not detected. Apparently, USC gamma adapted best to the oligotrophic cold climate conditions at the investigated pioneer sites.

• 出版日期2012