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Pseudomonas fluorescens Pf0-1
   
   
 
 
Pseudomonas fluorescens encompasses a group of common, nonpathogenic saprophytes that colonize soil, water and plant surface environments. As its name implies, it produces a soluble, greenish fluorescent pigment, particularly under conditions of low iron availability. It is a obligate aerobe, except for some strains that can utilize NO3 as an electron acceptor in place of O2. It is motile by means of multiple polar flagella. P. fluorescens has simple nutritional requirements and grows well in mineral salts media supplemented with any of a large number of carbon sources (1). Genetic techniques such as conjugation, transposition, and gene replacement are well established.

Strain Pf0-1 was isolated from agricultural soil and traits contribute to its survival and growth in this environment are being studied (2,3). Because they are well adapted to in soil, P. fluorescens strains are being investigated extensively for use in applications that require release and survival of bacteria in the soil. Chief among these are bioremediation of various organic compounds, and biocontrol of pathogens in agriculture.

Pseudomonads are noted for their metabolic diversity and are often isolated from enrichments designed to identify bacteria that degrade pollutants. Bioremediation applications seek to exploit the inherent metabolic diversity of P. fluorescens to partially or completely degrade pollutants such as styrene, TNT and, polycyclic aromatic hydrocarbons (4-6) . In addition, strains can be modified genetically to improve their performance in particular applications.

A number of strains of P. fluorescens suppress plant diseases by protecting the seeds and roots from fungal infection (7). This effect is the result of production of a number of secondary metabolites including antibiotics, siderophores and hydrogen cyanide. Competitive exclusion of pathogens as the result of rapid colonization of the rhizosphere by P. fluorescens may also be an important factor in disease control.

The sequence of the P. fluorescens genome will provide insight into its metabolic versatility and its interaction with the environment.

References

  1. Palleroni, N.J. (1984) Pseudomonadaceae. In Bergey's Manual of Systematic Biology. Kreig, N.R., and Holt, J.G. (eds). Baltimore: The Williams and Wilkins Co., pg. 141-199.

  2. Compeau, G., Al-Achi, B.J., Platsouka, E., and Levy, S.B. (1988) Survival of rifampicin-resistant mutants of Pseudomonas fluorescens and Pseudomonas putida in soil systems. Appl. Environ. Microbiol. 54: 2432-2438

  3. DeFlaun, M.F., Tanzer, A.S., McAteer, A.L., Marshall, B., and Levy, S.B. (1990) Development and characterization of an adhesion-deficient mutant of Pseudomonas fluorescens. Appl. Environ. Microbiol. 56: 112-119.

  4. Baggi, G., Boga, M.M., Catelani, D., Galli, E., and Treccani, V. (1983) Styrene catabolism by a strain of Pseudomonas fluorescens. Syst. Appl. Microbiol. 4: 141-147.

  5. Gilcrease P.C., and Murphy V.G. (1995) Conversion of 2,4-diamino-6-nitrotoluene to a novel metabolite under anoxic and aerobic conditions. Appl Environ Microbiol. 61: 4209-4214.

  6. Caldini, G., Cenci, G., Manenti, R., and Morozzi, G. (1995). The ability of an environmental isolate of Pseudomonas fluorescens to utilize chrysene and other four-ring polynuclear aromatic hydrocarbons. Appl. Microbiol. Biotechnol. 44: 225-229.

  7. O' Sullivan, D.B., and O'Gara, F. (1992) Traits of fluorescent Pseudomonas spp. involved in supression of plant root pathogens. Microbiol Rev 56: 662-676.