Azospirillum: A genus of gram-negative aerobic bacteria that occurs free-living in the soil or associated with the roots of cereal crops or grasses (POACEAE).Azospirillum brasilense: A species of motile, free-living, gram-negative bacteria that occur in the soil. They are aerobic or microaerophilic and are sometimes capable of nitrogen fixation.Nitrogen Fixation: The process in certain BACTERIA; FUNGI; and CYANOBACTERIA converting free atmospheric NITROGEN to biologically usable forms of nitrogen, such as AMMONIA; NITRATES; and amino compounds.Azospirillum lipoferum: A species of gram-negative to gram-variable, nitrogen-fixing bacteria. They are free-living in SOIL or found in association with PLANT ROOTS. It is the type species of the genus AZOSPIRILLUM.Gram-Negative Aerobic Bacteria: A large group of aerobic bacteria which show up as pink (negative) when treated by the gram-staining method. This is because the cell walls of gram-negative bacteria are low in peptidoglycan and thus have low affinity for violet stain and high affinity for the pink dye safranine.Nitrogenase: An enzyme system that catalyzes the fixing of nitrogen in soil bacteria and blue-green algae (CYANOBACTERIA). EC 126.96.36.199.Glutamate Synthase: An enzyme that catalyzes the formation of 2 molecules of glutamate from glutamine plus alpha-ketoglutarate in the presence of NADPH. EC 188.8.131.52.Flocculation: The aggregation of suspended solids into larger clumps.Agricultural Inoculants: Beneficial microorganisms (bacteria or fungi) encapsulated in carrier material and applied to the environment for remediation and enhancement of agricultural productivity.PII Nitrogen Regulatory Proteins: A family of signal transducing adaptor proteins that control the METABOLISM of NITROGEN. They are primarily found in prokaryotes.Dinitrogenase Reductase: A non-heme iron-sulfur protein isolated from Clostridium pasteurianum and other bacteria. It is a component of NITROGENASE along with molybdoferredoxin and is active in nitrogen fixation.Spirillum: A genus of gram-negative, curved and spiral-shaped bacteria found in stagnant, freshwater environments. These organisms are motile by bipolar tufts of flagella having a long wavelength and about one helical turn. Some species of Spirillum cause a form of RAT-BITE FEVER.Plant Roots: The usually underground portions of a plant that serve as support, store food, and through which water and mineral nutrients enter the plant. (From American Heritage Dictionary, 1982; Concise Dictionary of Biology, 1990)Fuel Oils: Complex petroleum hydrocarbons consisting mainly of residues from crude oil distillation. These liquid products include heating oils, stove oils, and furnace oils and are burned to generate energy.Hydroxybutyrates: Salts and esters of hydroxybutyric acid.Soil Microbiology: The presence of bacteria, viruses, and fungi in the soil. This term is not restricted to pathogenic organisms.Rhodospirillaceae: A family of phototrophic bacteria, in the order Rhodospirillales, isolated from stagnant water and mud.Polyesters: Polymers of organic acids and alcohols, with ester linkages--usually polyethylene terephthalate; can be cured into hard plastic, films or tapes, or fibers which can be woven into fabrics, meshes or velours.Genes, Bacterial: The functional hereditary units of BACTERIA.Triticum: A plant genus of the family POACEAE that is the source of EDIBLE GRAIN. A hybrid with rye (SECALE CEREALE) is called TRITICALE. The seed is ground into FLOUR and used to make BREAD, and is the source of WHEAT GERM AGGLUTININS.Phloroglucinol: A trinitrobenzene derivative with antispasmodic properties that is used primarily as a laboratory reagent.DNA, Bacterial: Deoxyribonucleic acid that makes up the genetic material of bacteria.AcetyleneAmmonia: A colorless alkaline gas. It is formed in the body during decomposition of organic materials during a large number of metabolically important reactions. Note that the aqueous form of ammonia is referred to as AMMONIUM HYDROXIDE.Gene Expression Regulation, Bacterial: Any of the processes by which cytoplasmic or intercellular factors influence the differential control of gene action in bacteria.Molecular Sequence Data: Descriptions of specific amino acid, carbohydrate, or nucleotide sequences which have appeared in the published literature and/or are deposited in and maintained by databanks such as GENBANK, European Molecular Biology Laboratory (EMBL), National Biomedical Research Foundation (NBRF), or other sequence repositories.RNA, Ribosomal, 16S: Constituent of 30S subunit prokaryotic ribosomes containing 1600 nucleotides and 21 proteins. 16S rRNA is involved in initiation of polypeptide synthesis.Atriplex: A plant genus in the CHENOPODIACEAE family.Herbaspirillum: A genus of gram-negative bacteria in the family OXALOBACTERACEAE, comprised of vibrioid or sometimes helical cells. They are chemoorganotrophic nitrogen fixers and are found free-living in the soil or in association with the roots of members of the GRAMINEAE. (From Bergey's Manual of Determinative Bacteriology, 9th ed)Bacterial Proteins: Proteins found in any species of bacterium.Phylogeny: The relationships of groups of organisms as reflected by their genetic makeup.