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dc.contributor.authorSantos-Caton, Ingrid R.
dc.contributor.authorCaton, Todd M.
dc.contributor.authorSchneegurt, Mark A.
dc.identifier.citationCaton, I.R., Caton, T.M. & Schneegurt, M.A. Arch Microbiol (2018) 200: 623en_US
dc.descriptionClick on the DOI link to access the article (may not be free).en_US
dc.description.abstractSmall streams exert great influences on the retention and attenuation of nitrogen (N) within stream networks. Human land use can lead to increased transport of dissolved inorganic N compounds and downstream eutrophication. Microbial activity in streams is important for maintaining an actively functioning N cycle. Chronically high N loading in streams affects the rates of the central processes of the N cycle by increasing rates of nitrification and denitrification, with biota exhibiting decreased efficiency of N use. The LINXII project measured N-cycle parameters in small streams using (NO3)-N-15 (-) tracer release experiments. We concurrently measured N-2 fixation rates in six streams of three types (agricultural, pristine, and urban prairie streams) as part of this broader study of major N-cycle processes. Nitrogen fixation in streams was significantly negatively correlated with nitrate levels, dissolved inorganic N levels, and denitrification rates. Algal mat and leaf litter samples generally exhibited the highest rates of N-2 fixation. The abundance of nifH genes, as measured by real-time PCR, was marginally correlated with N-2-fixation rates, but not to other N-cycle processes or stream characteristics. The nifH sequences observed were assigned to cyanobacteria, Deltaproteobacteria, Methylococcus, and Rhizobia. Seasonal changes, disturbances, and varying inputs may encourage a diverse, flexible, stable N-2-fixing guild. Patchiness in the streams should be considered when assessing the overall impact of N-2 fixation, since algal biomass exhibited high rates of N-2 fixation.en_US
dc.description.sponsorshipKansas National Science Foundation (NSF) Experimental Program to Stimulate Collaborative Research (EPSCoR) in Ecological Genomics (EPS 0236913) supported this work. Additional student support was from Kansas Institutional Development Award (IDeA) Networks of Biomedical Research Excellence (KINBRE) of the National Institute of General Medical Sciences (NIGMS) of the National Institutes of Health (NIH) (P20 GM103418) and NSF Graduate STEM Students in K-12 Education (GK-12; DGE 0537844).en_US
dc.publisherSpringer Berlin Heidelbergen_US
dc.relation.ispartofseriesArchives of Microbiology;v.200:no.4
dc.subjectNitrogen fixationen_US
dc.subjectReal-time PCRen_US
dc.titleNitrogen-fixation activity and the abundance and taxonomy of nifH genes in agricultural, pristine, and urban prairie stream sediments chronically exposed to different levels of nitrogen loadingen_US
dc.rights.holder© Springer-Verlag GmbH Germany, part of Springer Nature 2018en_US

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