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Archives of Ophthalmology (Chicago,... Sep 1981Ten cases of Azotobacter keratitis were identified at the Baylor College of Medicine and Cullen Eye Institute, Houston, from 1972 to 1980. Azotobacter are large,...
Ten cases of Azotobacter keratitis were identified at the Baylor College of Medicine and Cullen Eye Institute, Houston, from 1972 to 1980. Azotobacter are large, pleomorphic, aerobic, Gram-negative rods of the family Azotobacteraceae. The genus comprises four species (A beijerinckii, A chroococcum, A paspali, and A vinelandii) that are found in soil and water throughout the world. To our knowledge, Azotobactger species have not previously been recognized as causing human, animal, or plant disease. On the basis of the similarity of the organisms, other cases of Azotobacter keratitis may have been identified erroneously as Moraxella species.
Topics: Adolescent; Adult; Aged; Anti-Bacterial Agents; Azotobacter; Bacterial Infections; Female; Humans; Keratitis; Male; Microbial Sensitivity Tests; Middle Aged
PubMed: 7283809
DOI: 10.1001/archopht.1981.03930020461011 -
FEMS Microbiology Reviews Oct 2000The hypothesis of respiratory protection, originally formulated on the basis of results obtained with Azotobacter species, postulates that consumption of O(2) at the... (Review)
Review
The hypothesis of respiratory protection, originally formulated on the basis of results obtained with Azotobacter species, postulates that consumption of O(2) at the surface of diazotrophic prokaryotes protects nitrogenase from inactivation by O(2). Accordingly, it is assumed that, at increased ambient O(2) concentrations, nitrogenase activity depends on increased activities of a largely uncoupled respiratory electron transport system. The present review compiles evidence indicating that cellular O(2) consumption as well as both the activity and the formation of the respiratory system of Azotobacter vinelandii are controlled by the C/N ratio, that is to say the ratio at which the organism consumes the substrate (i.e. the source of carbon, reducing equivalents and ATP) per source of compound nitrogen. The maximal respiratory capacity which can be attained at increased C/N ratios, however, is controlled, within limits, by the ambient O(2) concentration. When growth becomes N-limited at increased C/N ratios, cells synthesize nitrogenase and fix N(2). Under these diazotrophic conditions, cellular O(2) consumption remains constant at a level controlled by the O(2) concentration. Control by O(2) has been studied on the basis of both whole cell respiration and defined segments of the respiratory electron transport chain. The results demonstrate that the effect of O(2) on the respiratory system is restricted to the lower range of O(2) concentrations up to about 70 microM. Nevertheless, azotobacters are able to grow diazotrophically at dissolved O(2) concentrations of up to about 230 microM indicating that respiratory protection is not warranted at increased ambient O(2) concentrations. This conclusion is supported and extended by a number of results largely excluding an obvious relationship between nitrogenase activity and the actual rate of cellular O(2) consumption. On the basis of theoretical calculations, it is assumed that the rate of O(2) diffusion into the cells is not significantly affected by respiration. All of these results lead to the conclusion that, in the protection of nitrogenase from O(2) damage, O(2) consumption at the cell surface is less effective than generally assumed. It is proposed that alternative factors like the supply of ATP and reducing equivalents are more important.
Topics: Azotobacter; Carbon; Electron Transport; Nitrogen; Nitrogen Fixation; Nitrogenase; Oxygen; Oxygen Consumption; Substrate Specificity
PubMed: 10978541
DOI: 10.1111/j.1574-6976.2000.tb00545.x -
Advances in Applied Microbiology 2019Azotobacters have been used as biofertilizer since more than a century. Azotobacters fix nitrogen aerobically, elaborate plant hormones, solubilize phosphates and also... (Review)
Review
Azotobacters have been used as biofertilizer since more than a century. Azotobacters fix nitrogen aerobically, elaborate plant hormones, solubilize phosphates and also suppress phytopathogens or reduce their deleterious effect. Application of wild type Azotobacters results in better yield of cereals like corn, wheat, oat, barley, rice, pearl millet and sorghum, of oil seeds like mustard and sunflower, of vegetable crops like tomato, eggplant, carrot, chillies, onion, potato, beans and sugar beet, of fruits like mango and sugar cane, of fiber crops like jute and cotton and of tree like oak. In addition to the structural genes of the enzyme nitrogenase and of other accessory proteins, A. vinelandii chromosomes contain the regulatory genes nifL and nifA. NifA must bind upstream of the promoters of all nif operons for enabling their expression. NifL on activation by oxygen or ammonium, interacts with NifA and neutralizes it. Nitrogen fixation has been enhanced by deletion of nifL and by bringing nifA under the control of a constitutive promoter, resulting in a strain that continues to fix nitrogen in presence of urea fertilizer. Additional copies of nifH (the gene for the Fe-protein of nitrogenase) have been introduced into A. vinelandii, thereby augmenting nitrogen fixation. The urease gene complex ureABC has been deleted, the ammonia transport gene amtB has been disrupted and the expression of the glutamine synthase gene has been regulated to enhance urea and ammonia excretion. Gluconic acid has been produced by introducing the glucose dehydrogenase gene, resulting in enhanced solubilization of phosphate.
Topics: Ammonium Hydroxide; Azotobacter; Azotobacter vinelandii; Bacterial Proteins; Fertilizers; Gene Expression Regulation, Bacterial; Genes, Bacterial; Genes, Regulator; Genetic Engineering; Glucose 1-Dehydrogenase; Glutamate-Ammonia Ligase; Microorganisms, Genetically-Modified; Nitrogen; Nitrogen Fixation; Nitrogenase; Phosphates; Transcription Factors; Urea; Urease
PubMed: 31495403
DOI: 10.1016/bs.aambs.2019.07.001 -
Nature Dec 1957
Topics: Azotobacter; Calcium; Water-Electrolyte Balance
PubMed: 13493583
DOI: 10.1038/1801493a0 -
World Journal of Microbiology &... Jan 2014A total of 14 Azotobacter strains were isolated from different paddy cultivating soils with pH ranging from 6.5 to 9.5 by using serial dilution agar plate method. The...
A total of 14 Azotobacter strains were isolated from different paddy cultivating soils with pH ranging from 6.5 to 9.5 by using serial dilution agar plate method. The strains were Gram negative, rod shaped, cyst forming and developed brown to black colored colonies, which were glistening, smooth, slimy on Ashby's agar plates. Biochemically they were positive for biochemical tests namely, indole production, citrate, catalase, carbohydrate fermentation and Voges-Proskauer test. Further, sequence analysis of PCR amplicons obtained from these cultures revealed the presence of five different Azotobacter species viz., Azotobacter vinelandii, Azotobacter salinestris, Azotobacter sp., Azotobacter nigricans subsp. nigricans and Azotobacter tropicalis. Phylogenetically these strains were grouped into two distinct clusters. These strains were tested for their ability to grow on a media containing four different pesticides such as pendimethalin, glyphosate, chloropyrifos and phorate, which are commonly used for the paddy. Out of 14 strains tested, 13 strains were able to grow on a media containing herbicides such as pendimethalin, glyphosate and insecticides like chloropyrifos and phorate. However, five Azotobacter strains were able to grow at higher concentration of 5% pesticides, without affecting their growth rate. Further, the effect of pesticides on the indole acetic acid (IAA) production by Azotobacter strains was also estimated. Azotobacter-16 strain was found to produce 34.4 μg ml(-l) of IAA in a media supplemented with 1,000 mg of tryptophan and 5% of pendimethalin. Present study reveals that species of Azotobacter are able to grow and survive in the presence of pesticides and no significant effects were observed on the metabolic activities of Azotobacter species.
Topics: Azotobacter; Bacterial Typing Techniques; Cluster Analysis; DNA, Bacterial; Drug Tolerance; Genotype; India; Microbial Sensitivity Tests; Molecular Sequence Data; Pesticides; Phylogeny; Sequence Analysis, DNA; Soil Microbiology
PubMed: 23813305
DOI: 10.1007/s11274-013-1412-3 -
Scientific Reports Sep 2015Microbial communities in rhizosphere interact with each other and form a basis of a cumulative impact on plant growth. Rhizospheric microorganisms like Piriformospora...
Microbial communities in rhizosphere interact with each other and form a basis of a cumulative impact on plant growth. Rhizospheric microorganisms like Piriformospora indica and Azotobacter chroococcum are well known for their beneficial interaction with plants. These features make P. indica/A. chroococcum co-inoculation of crops most promising with respect to sustainable agriculture and to understanding the transitions in the evolution of rhizospheric microbiome. Here, we investigated interactions of P. indica with A. chroococcum in culture. Out of five Azotobacter strains tested, WR5 exhibited growth-promoting while strain M4 exerted growth-inhibitory effect on the fungus in axenic culture. Electron microscopy of co-culture indicated an intimate association of the bacterium with the fungus. 2-D gel electrophoresis followed by mass spectrometry of P. indica cellular proteins grown with or without WR5 and M4 showed differential expression of many metabolic proteins like enolase-I, ureaseD, the GTP binding protein YPT1 and the transmembrane protein RTM1. Fungal growth as influenced by bacterial crude metabolites was also monitored. Taken together, the results conform to a model where WR5 and M4 influence the overall growth and physiology of P. indica which may have a bearing on its symbiotic relationship with plants.
Topics: Azotobacter; Basidiomycota; Fungal Proteins; Microbial Interactions; Proteome; Proteomics; Secondary Metabolism
PubMed: 26350628
DOI: 10.1038/srep13911 -
Virology Apr 1980
Topics: Azotobacter; Bacteriophages; Flagella; Glycoside Hydrolases; Lysogeny; Polysaccharides, Bacterial; Viral Plaque Assay
PubMed: 7368570
DOI: 10.1016/0042-6822(80)90094-x -
Journal of Bacteriology Nov 1985Azotobacter vinelandii exhibited diauxie when grown in a medium containing both acetate and glucose as carbon sources. Acetate was used as the primary carbon source...
Azotobacter vinelandii exhibited diauxie when grown in a medium containing both acetate and glucose as carbon sources. Acetate was used as the primary carbon source during the acetate-glucose diauxie. Uptake of acetate was constitutively expressed during both diauxic phases of growth. Induction of the glucose uptake system was inhibited in the presence of acetate. Acetate was also the preferred growth substrate for A. vinelandii grown in a medium containing either fructose, maltose, xylitol, or mannitol. The tricarboxylic acid cycle intermediates citrate, isocitrate, and 2-oxoglutarate inhibited glucose utilization in cells grown in glucose medium containing these substrates, and diauxic growth was observed under these growth conditions. Temporal expression of isocitrate-lyase, ATPase, and nitrogenase was exhibited during acetate-glucose diauxie.
Topics: Acetates; Adenosine Triphosphate; Azotobacter; Biological Transport; Citrates; Culture Media; Glucose; Isocitrate Lyase; Isocitrates; Ketoglutaric Acids; Kinetics; Nitrogen Fixation; Nitrogenase
PubMed: 3863813
DOI: 10.1128/jb.164.2.866-871.1985 -
Journal of Bacteriology Mar 1969Analyses of resting cells of Azotobacter vinelandii revealed that numerous phospholipids were present that did not concentrate in the membranous R(3) fraction which...
Analyses of resting cells of Azotobacter vinelandii revealed that numerous phospholipids were present that did not concentrate in the membranous R(3) fraction which carried out electron transport function.
Topics: Azotobacter; Chromatography; Electron Transport; Phospholipids; Ultracentrifugation
PubMed: 5776538
DOI: 10.1128/jb.97.3.1507-1508.1969 -
Proceedings of the National Academy of... Jan 1970Mutants of Azotobacter which grow normally on excess ammonia under a variety of conditions and which grow slowly or not at all on atmospheric nitrogen have been...
Mutants of Azotobacter which grow normally on excess ammonia under a variety of conditions and which grow slowly or not at all on atmospheric nitrogen have been isolated. Extracts of these strains have low or no detectable nitrogenase activity. There are three classes of mutants. Cell-free preparations of members of the first class possess an enhancement factor (EF+) which stimulates wild-type nitrogenase in vitro. Homogenates of members of the second class possess an enhanceable factor (EF-) which complements in vitro with extracts of the first class of mutants to give substantial nitrogenase activity. Preparations of members of the third class contain neither EF+ nor EF- activity. EF+ and EF- are repressed by the same conditions that repress nitrogenase. Molybdenum-deficient cells of the second class of mutants do not appear to contain EF- activity, but molybdenum deficient cells of the first class of mutants contain EF+. Because of these observations, EF+ is tentatively equated to azoferredoxin and EF- to molybdoferredoxin.
Topics: Azotobacter; Bacteriophages; Cell-Free System; Ferredoxins; Genetic Complementation Test; Genetics, Microbial; Microbial Sensitivity Tests; Molybdenum; Mutation; Nitrogen Fixation; Oxidoreductases
PubMed: 5263763
DOI: 10.1073/pnas.65.1.74