Primary production in coastal waters is generally nitrogen (N) limited with denitrification outpacing nitrogen fixation (N2-fixation). However, recent work suggests that we have potentially underestimated the importance of heterotrophic sediment N2-fixation in marine ecosystems. We used clone libraries to examine transcript diversity of nifH (a gene associated with N2-fixation) in sediments at ...

Scleractinian corals are essential constituents of tropical reef ecological diversity. They live in close association with diazotrophs [dinitrogen (N2)-fixing microbes], which can fix high rates of N2. Whether corals benefit from this extrinsic nitrogen source is still under debate. Until now, N2 fixation rates have been indirectly estimated using the acetylene reduction assay, which does not p...

The catalytic profile and function of each component of a molybdenum-graphene based catalyst (Mo/N-doped graphene) for nitrogen fixation, which combines the merits of these two components, is evaluated computationally. The Mo/N part acts as an active centre for N2 bond breaking and the graphene part works as an electron transmitter and electron reservoir.

Trichodesmium sp. is a filamentous, colonial cyanobacterium which contributes substantially to the input of nitrogen in tropical and subtropical oceanic waters through nitrogen fixation (N(2) fixation). We applied a N tracer technique to assess the rate of release of dissolved organic nitrogen (DON) from this cyanobacterium and compared those rates with rates of N(2) fixation determined for the...

Ten aromatic amino acid auxotrophs of Sinorhizobium meliloti (previously called Rhizobium meliloti) Rmd201 were generated by random mutagenesis with transposon Tn5 and their symbiotic properties were studied. Normal symbiotic activity, as indicated by morphological features, was observed in the tryptophan synthase mutants and the lone tyrosine mutant. The trpE and aro mutants fixed trace amount...

[1] Carbon-climate feedback has been identified as one of the key areas of synthesis for the next Inter-governmental Panel on Climate Change (IPCC); however, most of the models on which the IPCC will rely are yet to consider vital interactions between nitrogen (N) and carbon (C) cycles. A major impediment to including N limitation in model predictions has been the lack of constraint to rates of...

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Environmental Sciences Department, Brookhaven National Laboratory, Upton, New York 11973 (A.R.); Department of Plant Biology (E.A.A., A.D.B.L.), Department of Crop Sciences (A.R., E.A.A.), and Institute for Genomic Biology (E.A.A., A.D.B.L.), University of Illinois at Urbana-Champaign, Urbana, Illinois 61801; and Photosynthesis Research Unit, United States Department of Agriculture/Agricultural...

The discovery three years ago of thefirst well-defined complex compound containing the nitrogen molecule a complex of ruthenium aroused great interest in such compounds and in their relation to nitrogen fixation. Since then a number of other nitrogen complexes have been obtained, but as yet, despite reports to the contrary, attempts to reduce their nitrogen to ammonia have been unsuccessful. In...