Pseudomonas fluorescens

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Pseudomonas fluorescens
Scientific classification
Kingdom: Bacteria
Phylum: Proteobacteria
Class: Gamma Proteobacteria
Order: Pseudomonadales
Family: Pseudomonadaceae
Genus: Pseudomonas
Species: P. fluorescens
Binomial name
Pseudomonas fluorescens
(Flügge 1886)
Migula, 1895
Type strain
ATCC 13525

CCUG 1253
CCEB 546
CFBP 2102
CIP 69.13
DSM 50090
JCM 5963
LMG 1794
NBRC 14160
NCCB 76040
NCIMB 9046
NCTC 10038
NRRL B-14678
VKM B-894

Synonyms

Bacillus fluorescens liquefaciens Flügge 1886
Bacillus fluorescens Trevisan 1889
Bacterium fluorescens (Trevisan 1889) Lehmann and Neumann 1896
Liquidomonas fluorescens (Trevisan 1889) Orla-Jensen 1909
Pseudomonas lemonnieri (Lasseur) Breed 1948
Pseudomonas schuylkilliensis Chester 1952
Pseudomonas washingtoniae (Pine) Elliott

Pseudomonas fluorescens is a common Gram-negative, rod-shaped bacterium[1]. It belongs to the Pseudomonas genus; 16S rRNA analysis has placed P. fluorescens in the P. fluorescens group within the genus[2], to which it lends its name.

General characteristics

P. fluorescens has multiple flagella. It has an extremely versatile metabolism, and can be found in the soil and in water. It is an obligate aerobe but certain strains are capable of using nitrate instead of oxygen as a final electron acceptor during cellular respiration.

Optimal temperatures for growth of Pseudomonas fluorescens are 25-30 degrees Celsius. It tests positive for the oxidase test.

Heat stable lipases and proteases are produced by Pseudomonas fluorescens and other similar pseudomonads [3]. These enzymes cause milk to spoil, by causing bitterness, casein breakdown, and ropiness due to production of slime and coagulation of proteins [4][5].

The name

The word Pseudomonas means 'false unit', being derived from the Greek words pseudo (Greek: ψευδο 'false') and monas (Latin: monas, fr. Greek: μονάς/μονάδα 'a single unit'). The word was used early in the history of microbiology to refer to germs. The name 'fluorescens' is due to the fact that secretes a soluble fluorescent pigment called pyoverdin (formerly called fluorescein), which is a type of siderophore[6].

Genome sequencing projects

The genomes of P. fluorescens strains SBW25[7], Pf-5[8] and PfO-1[9] have been sequenced.

Biocontrol properties

Some P. fluorescens strains (CHA0 or Pf-5 for example) present biocontrol properties, protecting the roots of some plant species against parasitic fungi such as Fusarium or Pythium, as well as some phytophagous nematodes[10].

It is not clear exactly how the plant growth promoting properties of P. fluorescens are achieved; theories include:

  • that the bacteria might induce systemic resistance in the host plant, so it can better resist attack by a true pathogen
  • the bacteria might out compete other (pathogenic) soil microbes, e.g. by siderophores giving a competitive advantage at scavenging for iron
  • the bacteria might produce compounds antagonistic to other soil microbes, such as phenazine-type antibiotics or hydrogen cyanide

There is experimental evidence to support all of these theories, in certain conditions; a good review of the topic is written by Haas and Defago[11].

Medical Properties

By culturing Pseudomonas fluorescens, Mupirocin (an antibiotic) can be produced, which has been found to be useful in treating skin, ear and eye disorders[12]. Mupirocin free acid and its salts and esters are agents currently used in creams, ointments, and sprays as a treatment of Methicillin-resistant Staphylococcus aureus (MRSA) infection.

P. fluorescens demonstrates hemolytic activity and as a result has been known to infect blood transfusions[13].

It is also used in milk to make yogurt.

United States Patents: 6489358, 4873012, 6156792

References

  1. Palleroni, N.J. (1984) Pseudomonadaceae. Bergey's Manual of Systematic Bacteriology. Krieg, N. R. and Holt J. G. (editors) Baltimore: The Williams and Wilkins Co., pg. 141 - 199
  2. Anzai; et al. (2000, Jul). "Phylogenetic affiliation of the pseudomonads based on 16S rRNA sequence". Int J Syst Evol Microbiol. 50 (Pt 4): 1563–89. PMID 10939664. Check date values in: |year= (help)
  3. Frank, J.F. 1997. Milk and dairy products. In Food Microbiology, Fundamentals and Frontiers, ed. M.P. Doyle, L.R. Beuchat, T.J. Montville, ASM Press, Washington, p. 101.
  4. Jay, J.M. 2000. Taxonomy, role, and significance of microorganisms in food. In Modern Food Microbiology, Aspen Publishers, Gaithersburg MD, p. 13.
  5. Ray, B. 1996. Spoilage of Specific food groups. In Fundamental Food Microbiology, CRC Press, Boca Raton FL, p. 220.
  6. C D Cox and P Adams (1985) Infection and Immunity 48(1): 130–138
  7. http://www.sanger.ac.uk/Projects/P_fluorescens/
  8. http://cmr.tigr.org/tigr-scripts/CMR/GenomePage.cgi?org=gpf
  9. http://cmr.tigr.org/tigr-scripts/CMR/GenomePage.cgi?org=ntpf02
  10. Haas, D. and Keel, C. (2003) Regulation of antibiotic production in root-colonizing Pseudomonas spp. and relevance for biological control of plant disease. Annual Reviews of Phytopathology 41, 117-153 PMID 12730389
  11. Haas D, Defago G. (2005) Biological control of soil-borne pathogens by fluorescent pseudomonads. Nature Reviews in Microbiology 3(4):307-19 PMID 15759041
  12. http://www.netdoctor.co.uk/medicines/100000220.html
  13. Gibb AP, Martin KM, Davidson GA, Walker B, Murphy WG. (1995) Rate of growth of Pseudomonas fluorescens in donated blood. Journal of Clinical Patholology 48(8):717-8. PMID 7560196

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