Project II.2.3f: Characterizing communities - Soil-to-River-to-Ocean Crenarchaeota
Project Name: II.2.3f Characterizing communities - Soil-to-River-to-Ocean Crenarchaeotan
Project Leads: Lydie Herfort and Peter Zuber
Project Description
Our goal is to improve our understanding of non-extremophilic Crenarchaeota (one of the main archaeal groupings) along a Soil-to-River-to-Ocean gradient during Columbia river pre-freshet (organic matter mostly from run-off) and freshet (organic matter mostly from snow melt) conditions.
Marine non-extremophylic Crenarchaeota are known to comprise both autotrophs and heterotrophs, and a potential for nitrification mediated by Crenarchaeota in soil, river and marine environments has recently been reported. Crenarchaeotal nitrification has even been suggested to surpass bacterial nitrification in some settings. Hence, Crenarchaeota are important environmental microorganisms, yet little is known about pelagic riverine and estuarine Crenarchaeota and their importance in nitrification. The isopenoid membrane lipid, crenarchaeol, was originally assigned as a specific biomarker for marine non-extremophilic Crenarchaeota and consequently used in paleo-studies (e.g. BIT index, TEX86). Recent studies show that this lipid is also present in non-extreme environments such as river water and soil. Determination of crenarchaeol and Crenarchaeota presence in modern settings will better constrain the limitation of crenarchaeol-based paleo-proxies and will allow comparisons of crenarchaeol concentrations with crenarchaeotal nitrification. We will measure isoprenoid lipid concentrations, crenarchaeotal ammonia monooxygenase gene (amoA) expression by microarray-based mRNA measurement, and community structure of archaeal assemblages by denaturing gradient gel electrophoresis (DGGE) and nucleotide sequencing.
Fit in program
Crenarcaheota play an important role in carbon and nitrogen cycles, so it is essential that they are studied along a Soil-to-River-to-Ocean in the Pacific North West in order to get a better understanding of their role in global element cycles.
Outcomes
Surface, bottom water and surface sediment samples were collected in the Columbia river, its estuary, plume and coastal ocean in April and June 2008. Soil samples were collected at several sites around the estuary and in Oregon volcanic mountain ‘Mount Hood’ in July 2008.
