HR: 0800h
AN: B11A-1025 [Abstracts]
TI: Linking Biogeochemistry to Microbial Diversity Using New 13C Approaches
AU: * Baggs, E M
EM: e.baggs@abdn.ac.uk
AF: University of Aberdeen, School of Biological Sciences,
St Machar Drive, Aberdeen, AB24 3UU
United Kingdom
AB:
The use of 13C enables us to overcome uncertainties associated with soil C processes and to assess the links between
species diversity and ecosystem function. Recent advances in stable isotope techniques enable determination of process rates,
for example CH4 oxidation by direct measurement of 13C-CH4 and 13C-CO2. This overcomes
uncertainties associated with reliance on changes in net CH4 emission, which may have compromised some earlier studies
as both methanogenesis and CH4 oxidation may occur simultaneously in soil, providing significant advances in our
understanding of the process of CH4 oxidation. These stable isotope techniques can be combined with molecular techniques
(analysis of gene expression, stable isotope probing (SIP)) to relate the measured process to the microbial populations
responsible. Here we will give a synthesis of results from experiments in which we applied 13C-CH4 to accurately
determine CH4 oxidation rates in soils, and also present results of 13C-SIP from which we can identify the key
players in the microbial population that are using the applied 13C substrate. With the 13C-CH4 technique we
were able to provide direct evidence of inhibition of CH4 oxidation following fertiliser application (50-300 kg N
ha-1) that was less under elevated pCO2, and evidence for anaerobic CH4 oxidation occurring in soil at 75%
soil water filled pore space that would not have been apparent from changes in net CH4 emissions. 13C-SIP both
through plants (using 13C-CO2) and directly into soil (using 13C-methane and -organic substrates) has revealed
how key players in C utilisation vary under different soil conditions, for example, under improved and unimproved
grasslands.
DE: 0420 Biomolecular and chemical tracers
DE: 0428 Carbon cycling (4806)
DE: 0465 Microbiology: ecology, physiology and genomics (4840)
DE: 0486 Soils/pedology (1865)
DE: 0490 Trace gases
SC: Biogeosciences [B]
MN: Fall Meeting 2005