HR: 1340h
AN: B43A-0235    [Abstracts]
TI: The 15N /14N and 13C/12C natural abundance isotope composition of microbial biomass or DNA in soil.
AU: Dijkstra, P
EM: Paul.Dijkstra@nau.edu
AF: Dept. of Biology, Northern Arizona University Box 5640, Flagstaff, AZ 86011-5640 United States
AU: * Schwartz, E
EM: Egbert.Schwartz@nau.edu
AF: Dept. of Biology, Northern Arizona University Box 5640, Flagstaff, AZ 86011-5640 United States
AU: Hart, S C
EM: Steve.Hart@nau.edu
AF: Dept. of Forestry, Northern Arizona University, Flagstaff, AZ 86011 United States
AU: Hungate, B
EM: Bruce.Hungate@nau.edu
AF: Dept. of Biology, Northern Arizona University Box 5640, Flagstaff, AZ 86011-5640 United States
AB: Using a modified chloroform fumigation procedure, we have measured the 15N /14N and 13C/12C natural abundance isotope composition of microbial biomass. In addition, we have developed a protocol to measure the 15N /14N and 13C/12C natural abundance isotope composition of DNA extracted from soil. The results show DNA is depleted in 15N relative to the microbial biomass, the microbial biomass but not the DNA is 15N enriched compared to total soil and the extractable N, and that the 13C and 15N-enrichment is variable between different soils. We will present data from soils along an elevation gradient, in Northern Arizona and an age gradient in Hawaii. We present two conceptual mechanistic models to explain our findings and discuss how these measurements may help in increasing our understanding of organic matter decomposition in soil.
DE: 0428 Carbon cycling (4806)
DE: 0454 Isotopic composition and chemistry (1041, 4870)
DE: 0465 Microbiology: ecology, physiology and genomics (4840)
SC: Biogeosciences [B]
MN: Fall Meeting 2005