Pseudomonas fluorescens

from Wikipedia, the free encyclopedia
Pseudomonas fluorescens
Pseudomonas fluorescens in Gram stain

Pseudomonas fluorescens in Gram stain

Systematics
Domain : Bacteria (bacteria)
Class : Gammaproteobacteria
Order : Pseudomonadales
Family : Pseudomonadaceae
Genre : Pseudomonas
Type : Pseudomonas fluorescens
Scientific name
Pseudomonas fluorescens
Migula 1895

Pseudomonas fluorescens is a gram-negative , oxidase-positive , rod-shaped bacterium of the genus Pseudomonas with a pole-shapedflagella tuft. Like other pseudomonads, P. fluorescens secretes siderophores called pyoverdins (= bacterial fluorescein ), which fluoresce under UV light. The bacterium is aerobic and occurs in soil, water and plants.
P. fluorescens is one of the rarely isolated Pseudomonas species that are important for human medicine. However, P. fluorescens is more important in soil biology and food spoilagethan in medicine.

Soil biology

Some P. fluorescens strains are important soil organisms because they are able to suppress a number of phytopathogenic germs. In this way, natural suppressive soils can arise. This effect is due to the fact that these P. fluorescens strains produce antibiotics as secondary metabolites , so that the colonization of the roots by such strains leads to an induced systemic resistance of the plant or so that such strains are often very specific antagonists of certain pathogens.

Antibiotics

The genome of strain Pf-5 has been completely sequenced. Four already known gene complexes were found that code for toxic secondary metabolites for fungi or egg fungi . These were pyoluteorin, 2,4-diacetylphloroglucinol, pyrrole nitrine and hydrogen cyanide . In addition, three previously unknown gene complexes were discovered that may also code for secondary metabolites. Gene complexes for the non-ribosomal creation and uptake of the pyoverdin siderophores were also found (position and orientation differ from those of known gene complexes in other microorganisms ).
Since pyoverdines are very effective siderophores, phytopathogenic bacteria can be inhibited in pH-neutral to basic soils (Fe 3+ ions are poorly soluble) because they cannot absorb enough Fe 3+ ions. The boundaries are blurred here, however, because antibiotics are secondary metabolites, while iron is required in the primary metabolism. Nevertheless, the primary metabolism has an inhibiting effect on the growth of phytopathogenic germs.
It should be similar with pyochelin. The gene complexes for its generation were also detected in strain Pf-5. Pyochelin is a strong Cu 2+ - and Zn 2+ - chelator and could thus act by removal of these ions inhibitory to fungal growth.

Induced systemic resistance

It is not known exactly how bacteria at the roots interact with a plant to induce systemic resistance. However, the production of the secondary metabolite 2,4-diacetylphloroglucinol seems to play an important role. In addition, P. fluorescens can increase plant resistance through the production of the plant hormone cytokinin .

Food spoilage

P. fluorescens can secrete proteolytic and lipolytic enzymes and lives aerobically and psychrotrophically . This is why P. fluorescens, together with Pseudomonas fragi and Pseudomonas putida, is one of the most common gram-negative, psychrotolerant germs involved in the spoilage of milk. The secreted enzymes are heat-stable and remain active even after pasteurization and ultra-high-temperature heating.
Another problem with milk processing is the colonization by P. fluorescens after pasteurization. The processing environment is a possible source of such colonization.

Medical importance

P. fluorescens is often found in blood products . This is related to the ability of the bacterium to continue to grow even at 4 ° C ( psychrophilia ). This germ is thus one of the two most common causes of sepsis after a transfusion with germ-contaminated blood.

Individual evidence

  1. ↑ Michael T. Madigan, John M. Martinko: Brock Microbiology. Translated from the English by Dr. Thomas Lazar and Freya Thomm-Reitz. 11th updated edition. Pearson Studium, Munich 2009, ISBN 978-3-8273-7358-8 , pp. 373-391
  2. ↑ Ina Tammer, Alexandra Clarici, Frank Thies, Brigitte König, Wolfgang König: Nonfermenter: Pseudomonas spp. and related species. In: Birgid Neumeister (Ed.), Heinrich K. Geiss (Ed.), Rüdiger W. Braun (Ed.), Peter Kimmig (Ed.), U. a .: Microbiological diagnostics. Bacteriology - Mycology - Virology - Parasitology. 2nd completely revised edition. Georg Thieme Verlag, Stuttgart 2009, ISBN 978-3-13-743602-7 , pp. 476-481
  3. ↑ a b Dieter Haas, Geneviève Défago: Biological control of soil-born pathogens by fluorescent pseudomonads. In: Nature Reviews Microbiology . Advance Online Publication, March 10, 2005 doi : 10.1038 / nrmicro1129 , pp. 1-13
  4. ^ Ian T. Paulsen, Caroline M Press, et al. a .: Complete genome sequence of the plant comensal Pseudomonas fluorescens Pf-5. In: Nature Biotechnology . Vol. 23, No. 7, 2006 doi : 10.1038 / nbt1110 , pp. 873-878
  5. ↑ Annalisa Iavicoli, Emmanuel Boutet, Antony Buchala, and Jean-Pierre Métraux: Induced Systemic Resistance in Arabidopsis thaliana in Response to Root Inoculation with Pseudomonas fluorescens CHA0. In: Molecular Plant-Microbe Interactions. Vol. 16, No. 7, 2003, pp. 851-858
  6. ↑ Großkinsky DK, Tafner R, Moreno MV, Stenglein SA, García de Salamone IE, Nelson LM, Novák O, Strnad M, van der Graaff E, Roitsch T: Cytokinin production by Pseudomonas fluorescens G20-18 determines biocontrol activity against Pseudomonas syringae in Arabidopsis . In: Scientific Reports . March 6, 2016. doi : 10.1038 / srep23310 . PMID 26984671 . PMC 4794740 (free full text).
  7. ↑ Martin Wiedmann, Denise Weilmeier, Sean S. Dineen, Robert Ralyea, Kathryn J. Boor: Molecular and Phenotypic Characterization of Pseudomonas spp. isolated from Milk. In: Applied and Environmental Microbiology. Vol. 66 No. 5, 2000 doi : 10.1128 / AEM.66.5.2085-2095.2000 , pp. 2085-2095
  8. ^ S. Rajmohan, CER Dodd, WM Waites: Enzymes from isolates of Pseudomonas fluorescens involved in food spoilage. In: Journal of Applied Microbiology. Vol. 93 No. 2, 2000 doi : 10.1046 / j.1365-2672.2002.01674.x , pp. 205-213
  9. ↑ Belgin Dogan, Kathryn J. Boor: Genetic Diversity and Spoilage Potentials among Pseudomonas spp. Isolated from Fluid Milk Products and Dairy Processing Plants. In: APPLIED AND ENVIRONMENTAL MICROBIOLOGY. Vol. 69 No. 1, 2003 doi : 10.1128 / AEM.69.1.130-138.2003 , pp. 130-138
  10. ↑ Gabriel Morduchowicz, Silvio D. Pitlik, David Huminer, Michael Alkan, Moshe Drucker, Joseph B. Rosenfeld, Colin S. Block: Transfusion Reactions Due to Bacterial Contamination of Blood and Blood Products. In: Reviews of Infectious Diseases. Vol. 13 No. 2, 1991, pp. 307-314
  11. ^ AP Gibb, KM Martin, GA Davidson, B. Walker, WG Murphy: Rate of growth of Pseudomonas fluorescens in donated blood. In: Journal of Clinical Pathology . Vol. 48 No. 8, 1995, pp. 717-718

Web links

Commons : Pseudomonas fluorescens  - collection of images, videos and audio files