HR: 1340h
AN: B13A-1052    [Abstracts]
TI: Linking Nano-Scale Patterns of 15N and 13C Metabolism to Bacterial Morphology with Secondary Ion Mass Spectrometry
AU: * Pett-Ridge, J
EM: pettridge2@llnl.gov
AF: Lawrence Livermore National Lab, P.O. Box 808, L231, Livermore, CA 94551 United States
AU: Fallon, S J
EM: fallon4@llnl.gov
AF: Lawrence Livermore National Lab, P.O. Box 808, L231, Livermore, CA 94551 United States
AU: Finzi, J A
EM: finzi@usc.edu
AF: University of Southern California, 3651 Trousdale Parkway, Los Angeles, CA 90089 United States
AU: Capone, D G
EM: capone@usc.edu
AF: University of Southern California, 3651 Trousdale Parkway, Los Angeles, CA 90089 United States
AU: Popa, R
EM: rpopa@usc.edu
AF: University of Southern California, 3651 Trousdale Parkway, Los Angeles, CA 90089 United States
AU: Nealson, K H
EM: knealson@usc.edu
AF: University of Southern California, 3651 Trousdale Parkway, Los Angeles, CA 90089 United States
AU: Hutcheon, I D
EM: hutcheon1@llnl.gov
AF: Lawrence Livermore National Lab, P.O. Box 808, L231, Livermore, CA 94551 United States
AU: Weber, P K
EM: weber21@llnl.gov
AF: Lawrence Livermore National Lab, P.O. Box 808, L231, Livermore, CA 94551 United States
AB: The technical challenges of tracing isotopes within individual bacteria can be overcome with high resolution Secondary Ion Mass Spectrometry (NanoSIMS). In NanoSIMS analysis, samples are sputtered with an energetic primary beam (Cs+, O-) liberating secondary ions that are separated by the mass spectrometer and detected in a suite of electron multipliers. Five isotopic species may be analyzed concurrently with spatial resolution as fine as 50nm. A high sensitivity isotope ratio `map' can then be generated for the analyzed area. We used this technique to quantitatively describe 13C and 15N uptake and transport in two marine cyanobacteria grown on NaH13CO3 and 15N2. These bacteria are faced with the challenge of isolating regions of N-fixation (O2 inhibited) and photosynthetic (O2 producing) activity. Patterns of isotope enrichment were resolved at multiple spatial scales ranging from sub-cellular variation, cell-cell differences along filaments, and within-cell depth profiles. Using sequentially harvested bacteria, we also measured temporal enrichment patterns that evolve over the course of a day's growth and suggest tightly regulated changes in fixation kinetics. Spatial enrichment patterns were correlated with morphological features evidenced in TEM images of microtomed filaments. These features indicate how 15N and 13C "hotspots" are dispersed throughout individual cells in different species, and may indicate isolated locations of increased N2 fixation, sites of amino acid/protein synthesis, or cyanophycin storage granules. This combination of Nano-Secondary Ion Mass Spectrometry (NanoSIMS) analysis and high resolution microscopy allows isotopic analysis to be linked to morphological features and holds great promise for fine-scale studies of bacteria metabolism.
DE: 0454 Isotopic composition and chemistry (1041, 4870)
DE: 0465 Microbiology: ecology, physiology and genomics (4840)
DE: 0469 Nitrogen cycling
DE: 0470 Nutrients and nutrient cycling (4845, 4850)
DE: 4870 Stable isotopes (0454, 1041)
SC: Biogeosciences [B]
MN: Fall Meeting 2005