Monodeuterated Methane, an Isotopic Tool To Assess Biological Methane Metabolism Rates

Tutkimustuotos: Lehtiartikkeli

Tutkijat

  • jeffrey Marlow
  • Joshua Steele
  • Wiebke Ziebis
  • Silvan Scheller

  • David Case
  • Linda Reynard
  • Victoria Orphan

Organisaatiot

  • California Institute of Technology

Kuvaus

Biological methane oxidation is a globally relevant process that mediates
the flux of an important greenhouse gas through both aerobic and anaerobic
metabolic pathways. However, measuring these metabolic rates presents many obstacles, from logistical barriers to regulatory hurdles and poor precision. Here we present a new approach for investigating microbial methane metabolism based on hydrogen atom dynamics, which is complementary to carbon-focused assessments of methanotrophy. The method uses monodeuterated methane (CH3D) as a metabolic substrate, quantifying the aqueous D/H ratio over time using off-axis integrated cavity output spectroscopy. This approach represents a nontoxic, comparatively rapid, and straightforward approach that supplements existing radiotopic and stable carbon isotopic methods; by probing hydrogen atoms, it offers an additional dimension for examining rates and pathways of methane metabolism. We provide direct comparisons between the CH3D procedure and the well-established 14CH4 radiotracer method for several methanotrophic systems, including type I and II aerobic methanotroph cultures and methane-seep sediment slurries and carbonate rocks under anoxic and oxic incubation conditions. In all applications tested, methane consumption values calculated via the CH3D method were directly and consistently proportional to 14C radiolabel-derived methane oxidation rates. We also employed this method in a nontraditional experimental setup, using flexible, gas-impermeable bags to investigate the role of pressure on seep sediment methane oxidation rates. Results revealed an 80% increase over atmospheric pressure in methanotrophic rates the equivalent of ~900-m water depth, highlighting the importance of this parameter on methane metabolism and exhibiting the flexibility of the newly described method.

Yksityiskohdat

AlkuperäiskieliEnglanti
Artikkelie00309-17
Sivut1-19
Sivumäärä19
JulkaisumSphere
Vuosikerta2
Numero4
TilaJulkaistu - 2017
OKM-julkaisutyyppiA1 Julkaistu artikkeli, soviteltu

ID: 15325698