Biomaterial Database

Association between Azotobacter and other soil bacteria and its effect on nitrogen fixation. 1979

Y Abd-el-Malek, and I Hosny, and B T Shawky

The association between A. vinelandii and either Agrobacterium sp. or Micrococcus sp., which are usually found as contaminants in Azotobacter cultures, was investigated. In comparison with pure cultures, association increased the microbiol counts in addition to increasing nitrogen fixation rates and efficiency. In liquid cultures higher Azotobacter densities were observed in the top 5 cm of the column concomitant with lowering the economic coefficient of utilization of carbonaceous compounds, which resulted in low efficiency of nitrogen fixation. In deep layers, lower amounts of nitrogen gain were obtained, but higher efficiencies of N2-fixation were recorded. In sand cultures, the biggest amounts of fixed nitrogen were in the 5--15 cm layer of the soil column and in deeper layers economic utilization of sugars occurred, but nitrogen gain sharply decreased.

UI	MeSH Term	Description	Entries
D008837	Micrococcus	A genus of gram-positive, spherical bacteria found in soils and fresh water, and frequently on the skin of man and other animals.
D009586	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.	Diazotrophy,Diazotrophic Activity,Dinitrogen Fixation,N2 Fixation,Activities, Diazotrophic,Activity, Diazotrophic,Diazotrophic Activities,Fixation, Dinitrogen,Fixation, N2,Fixation, Nitrogen
D003470	Culture Media	Any liquid or solid preparation made specifically for the growth, storage, or transport of microorganisms or other types of cells. The variety of media that exist allow for the culturing of specific microorganisms and cell types, such as differential media, selective media, test media, and defined media. Solid media consist of liquid media that have been solidified with an agent such as AGAR or GELATIN.	Media, Culture
D004534	Egypt	A country in northern Africa, bordering the Mediterranean Sea, between Libya and the Gaza Strip, and the Red Sea north of Sudan, and includes the Asian Sinai Peninsula Its capital is Cairo.	Arab Republic of Egypt,United Arab Republic
D001395	Azotobacter	A genus of gram-negative, aerobic bacteria found in soil and water. Its organisms occur singly, in pairs or irregular clumps, and sometimes in chains of varying lengths.
D001419	Bacteria	One of the three domains of life (the others being Eukarya and ARCHAEA), also called Eubacteria. They are unicellular prokaryotic microorganisms which generally possess rigid cell walls, multiply by cell division, and exhibit three principal forms: round or coccal, rodlike or bacillary, and spiral or spirochetal. Bacteria can be classified by their response to OXYGEN: aerobic, anaerobic, or facultatively anaerobic; by the mode by which they obtain their energy: chemotrophy (via chemical reaction) or PHOTOTROPHY (via light reaction); for chemotrophs by their source of chemical energy: CHEMOLITHOTROPHY (from inorganic compounds) or chemoorganotrophy (from organic compounds); and by their source for CARBON; NITROGEN; etc.; HETEROTROPHY (from organic sources) or AUTOTROPHY (from CARBON DIOXIDE). They can also be classified by whether or not they stain (based on the structure of their CELL WALLS) with CRYSTAL VIOLET dye: gram-negative or gram-positive.	Eubacteria
D012231	Rhizobium	A genus of gram-negative, aerobic, rod-shaped bacteria that activate PLANT ROOT NODULATION in leguminous plants. Members of this genus are nitrogen-fixing and common soil inhabitants.
D012988	Soil Microbiology	The presence of bacteria, viruses, and fungi in the soil. This term is not restricted to pathogenic organisms.	Microbiology, Soil
D013045	Species Specificity	The restriction of a characteristic behavior, anatomical structure or physical system, such as immune response; metabolic response, or gene or gene variant to the members of one species. It refers to that property which differentiates one species from another but it is also used for phylogenetic levels higher or lower than the species.	Species Specificities,Specificities, Species,Specificity, Species