Studies were carried out on the microflora of phyllosphere and soil rhizosphere of hulled (Chwat variety) and naked (Akt variety) oats. The material taken for study embraced samples of leaves and soil rhizosphere taken from cultivations differing in extent of nitrogen fertilization. The studies involved determination of total number of aerobic heterotrophic bacteria belonging to the genus Pseud...

1. Understanding ecological strategies of invasive species relative to the entire native community is important in understanding and managing both the mechanisms and the potential impacts of invasion, but few studies have taken this approach. 2. We utilize advances in plant ecology to compare functional traits of an invasive shrub species, autumn-olive Elaeagnus umbellata, to those of the under...

Many plants have evolved adaptations in order to survive in low nitrogen environments. One of the best-known adaptations is that of plant symbiosis with nitrogen-fixing bacteria; this is the major route by which nitrogen is incorporated into plant biomass. A portion of this plant-associated nitrogen is then lost to insects through herbivory, and insects represent a nitrogen reservoir that is ge...

The Eurasian basin of the Central Arctic Ocean is nitrogen limited, but little is known about the presence and role of nitrogen-fixing bacteria. Recent studies have indicated the occurrence of diazotrophs in Arctic coastal waters potentially of riverine origin. Here, we investigated the presence of diazotrophs in ice and surface waters of the Central Arctic Ocean in the summer of 2012. We ident...

Symbiotic nitrogen fixation, the process whereby nitrogen-fixing bacteria enter into associations with plants, provides the major source of nitrogen for the biosphere. Nitrogenase, a bacterial enzyme, catalyzes the reduction of atmospheric dinitrogen to ammonium. In rhizobia-leguminous plant symbioses, the current model of nitrogen transfer from the symbiotic form of the bacteria, called a bact...

The bacteriophage P1 infects and functions as a generalized transducing phage for nitrogen-fixing strains of the coliform bacterium Klebsiella pneumoniae. Bacterial mutants (nif(-)) unable to grow on molecular nitrogen as a nitrogen source were found to be deficient in nitrogenase activity as assayed by the conversion of acetylene to ethylene. These mutants regained normal nitrogenase activity ...

Root-nodule symbiosis between leguminous plants and nitrogen-fixing bacteria (rhizobia) involves molecular communication between the two partners. Key components for the establishment of symbiosis are rhizobium-derived lipochitooligosaccharides (Nod factors; NFs) and their leguminous receptors (NFRs) that initiate nodule development and bacterial entry. Here we demonstrate that the soybean micr...

Terrestrial autotrophs such as higher plants are confronted with challenges largely unknown to their counterparts in the seas, including extreme patchiness of inorganic nutrients. Evolution of higher plants has yielded interesting and important solutions to the problem of nutrient acquisition on land. Some of the most intriguing of these involve mutually beneficial symbioses. In fact, evolution...

Azotobacter chroococcum is a bacterium known to break the triple bond that forms N2. This is important for life that cannot devour other organisms that have already converted the N2 into usable forms. Nitrogen fixing bacteria break the triple bond and form compounds that plants and other bacteria can readily use. This same species of bacteria can also break the triple bond that appears in the c...