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Azotobacter vinelandii

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Azotobacter vinelandii
Scientific classification
Domain:
Bacteria
Phylum:
Proteobacteria
Class:
Gammaproteobacteria
Order:
Pseudomonadales
Family:
Pseudomonadaceae
Genus:
Azotobacter
Species:
A. vinelandii
Binomial name
Azotobacter vinelandii
Type strain
ATCC 478

DSM 2289

WR-100

Azotobacter vinelandii is a free-living, Gram-negative soil bacterium. Cells range in shape from rods to coccoid. For bacteria, cells of A. vinelandii are relatively large in size. Large cell size correlates with high DNA content. Cells are usually motile. Under certain conditions, cells undergo encystment. Capsule production is also common in most strains. Pigment production is a common feature of the Azotobacter genus, but A. vinelandii excretes a unique fluorescent pigment. A. vinelandii exhibits chemoheterotrophic growth[1]. Organisms of this species utilize various sugars and alcohols as carbon sources and ammonium, nitrate and urea as sources of nitrogen. A. vinelandii respires aerobically using different organic compounds as electron donors. This species is known to have the highest respiratory rate of all bacteria. The distinguishing characteristic of the genus is their ability to fix atmospheric nitrogen under aerobic or microaerobic conditions. In A. vinelandii, conversion of N2 to ammonia is catalyzed by 1 of 3 distinct, O2-sensitive nitrogenase enzymes[2]. Many different mechanisms and features unique to A. vinelandii work together to carry out this paradoxical diazotrophic growth, including regulatinbg oxygen consumption rates in order to keep the cytoplasmic O2 concentration low. Phylogenetic analysis reveals A. vindelandii is closely related to pseudomonads[3].

Isolation & enrichment

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A. vindelandii was discovered by Lipman in 1903. The organism was isolated from soils in Vineland, New Jersey.[4]. general habitats...[5] enrichment...

Growth/culutral characteristics

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Optimal growth pH is 7.0-7.5 [6]. Incubation at 37°C in N-free media favors growth of A. vinelandii [7]

Pigments

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A. vinelandii can be distinguished from other Azotobacter species upon comparison of differential pigment production. Colonies of A. vinelandii excrete yellow-green, green, or red-violet fluorescent pigments, especially under iron-limiting conditions. These water-soluble pigments diffuse into the agar and cause a color change of the medium [8].

Metabolism

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The ability of A. vindelandii to utilize phenol and rhamnose as sole carbon sources is a distintinguishing characteristic of the species.

Nitrogen fixation

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nitrogenases

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1. molybdenum nitrogenase 2. vanadium nitrogenase 3. iron-only nitrogenase [9]

respiratory protection mechanisms

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1. Respiratory proteins: terminal oxidases --> high oxygen consumption (fastest resp rates); ATP synthases --> high cellular levels [ATP]; 2. FeSII-Shenthna protein --> "conformational protection" : forms protective complex with nitrogenase enzyme 3. alginate capsule --> keeps cytoplasm anaerobic: physical O2 diffusion barrier

Morphology

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Azotobacter vinelandii are Gram-negative bacteria. The cells of A. vinelandii are realtively large in size; mean cell dimensions are 1.6 -2.5 μm wide by 3-5 μm long. Cells vary from rods to coccoid in shape and can occur singly or in pairs.

Externmal cell wall components

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Aside from a few rare nonmotile strains, A. vinelandii cells are motile by means of peritrichous flagella. One strain, A. vinelandii OP, has been measured moving at speeds of 74 μm per second[10]. Chemotaxis...

Capsules/S-layer

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PHB deposits serve as carbon and energy reserves.

Cysts

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[11]

Genomics

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Genomic characteristics vary between different strains in the species. By summing the lengths of restriction fragments found in two separate enzyme digestions, the genome size of A. vinelandii UW was determined to be 4.57 Mb. In addition, six copies of the rrn operon were found to be present. Complete genomic sequencing of A. vinelandii DJ revealed a single circular chromosome with a length of 5,365,318 base pairs [12]. The genome was sequenced using a shotgun sequencing approach. Assembling the genome entailed aligning sequences to optical map generated using restriction enzymes. The molecular guanine to cytosine ratio, as determined in Tm experiments, is 65.7%. A total of 5,051 protein-coding genes exist in the chromosome of this particular strain. high, variable # of chromosomes; up to 80 copies per cell.

Plasmids, ranging in size from 9 to 52 MDa, were found in four lab strains and two isolates of A. vinelandii[13].

Taxonomy and Phylogeny

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The genus name Azotobacter is derived from two Latin nouns: azotum, meaning nitrogen and bacter, meaning rod. The species name, vinelandii, is a derivation of the location where the species was first isolated, Vineland, New Jersey[14].

P. stutzeri [15] P. aeurginosa[16]

Applications

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alginate and PHB cynthesis[17]

References

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  1. ^ Becking, Jan Hendrik (2006). The Prokaryotes Volume 6: Proteobacteria: Gamma Subclass (3rd. ed.). New York: Springer. p. 759-783.
  2. ^ Kennedy, Christina; Rudnick, Paul; MacDonald, Melanie L.; Melton, Thoyd (2005). Bergey's Manual of Systematic Bacteriology Volume 2: The Proteobacteria, Part B: The Gammaproteobacteria (2nd ed.). New York: Springer. p. 384-402.
  3. ^ Setubal, Joao C.; dos Santos, Patricia; Goldman, Barry S. (July 2009). "Genome Sequence of Azotobacter vinelandii, an Obligate Aerobe Specialized To Support Diverse Anaerobic Metabolic Processes". Journal of Bacteriology. 191 (14): 4534-4545.
  4. ^ Kennedy, Christina; Rudnick, Paul; MacDonald, Melanie L.; Melton, Thoyd (2005). Bergey's Manual of Systematic Bacteriology Volume 2: The Proteobacteria, Part B: The Gammaproteobacteria (2nd ed.). New York: Springer. p. 384-402.
  5. ^ Becking, Jan Hendrik (2006). The Prokaryotes Volume 6: Proteobacteria: Gamma Subclass (3rd. ed.). New York: Springer. p. 759-783.
  6. ^ Kennedy, Christina; Rudnick, Paul; MacDonald, Melanie L.; Melton, Thoyd (2005). Bergey's Manual of Systematic Bacteriology Volume 2: The Proteobacteria, Part B: The Gammaproteobacteria (2nd ed.). New York: Springer. p. 384-402.
  7. ^ Becking, Jan Hendrik (2006). The Prokaryotes Volume 6: Proteobacteria: Gamma Subclass (3rd. ed.). New York: Springer. p. 759-783.
  8. ^ Becking, Jan Hendrik (2006). The Prokaryotes Volume 6: Proteobacteria: Gamma Subclass (3rd. ed.). New York: Springer. p. 759-783.
  9. ^ Kennedy, Christina; Rudnick, Paul; MacDonald, Melanie L.; Melton, Thoyd (2005). Bergey's Manual of Systematic Bacteriology Volume 2: The Proteobacteria, Part B: The Gammaproteobacteria (2nd ed.). New York: Springer. p. 384-402.
  10. ^ Cite error: The named reference Kennedy was invoked but never defined (see the help page).
  11. ^ Sadoff, Harold L. Encystment and Germination in Azotobacter vinelandii.
  12. ^ Setubal, Joao C.; dos Santos, Patricia; Goldman, Barry S. (July 2009). "Genome Sequence of Azotobacter vinelandii, an Obligate Aerobe Specialized To Support Diverse Anaerobic Metabolic Processes". Journal of Bacteriology. 191 (14): 4534-4545.
  13. ^ Maia, Mauricio; Sanchez, Juan M.; Vela, G. R. (April 1988). "Plasmids of Azotobacter vinelandii". Journal of Bacteriology. 170 (4): 1984-1985.
  14. ^ Kennedy, Christina; Rudnick, Paul; MacDonald, Melanie L.; Melton, Thoyd (2005). Bergey's Manual of Systematic Bacteriology Volume 2: The Proteobacteria, Part B: The Gammaproteobacteria (2nd ed.). New York: Springer. p. 384-402.
  15. ^ Setubal, Joao C.; dos Santos, Patricia; Goldman, Barry S. (July 2009). "Genome Sequence of Azotobacter vinelandii, an Obligate Aerobe Specialized To Support Diverse Anaerobic Metabolic Processes". Journal of Bacteriology. 191 (14): 4534-4545.
  16. ^ Ozen, Asli I.; Ussery, David W. (2012). "Defining the Pseudomonas Genus: Where Do We Draw the Line with Azotobacter?". Microb ecol (63): 239-248.
  17. ^ Galindo, Enrique; Pena, Carlos; Nunuz, Cinthia (2007). "Molecular and bioengineering strategies to improve alginate and polydydroxyalkanoate production by Azotobacter vinelanii". Microbial Cell Factories. 6 (7).

[1] [2] [3]

  1. ^ Kennedy, Christina; Rudnick, Paul; MacDonald, Melanie L.; Melton, Thoyd (2005). Bergey's Manual of Systematic Bacteriology Volume 2: The Proteobacteria, Part B: The Gammaproteobacteria (2nd ed.). New York: Springer. p. 384-402.
  2. ^ Setubal, Joao C.; dos Santos, Patricia; Goldman, Barry S. (July 2009). "Genome Sequence of Azotobacter vinelandii, an Obligate Aerobe Specialized To Support Diverse Anaerobic Metabolic Processes". Journal of Bacteriology. 191 (14): 4534-4545.
  3. ^ Becking, Jan Hendrik (2006). The Prokaryotes Volume 6: Proteobacteria: Gamma Subclass (3rd. ed.). New York: Springer. p. 759-783.
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