Get to know Pseudomonas fluorescens
Pseudomonas fluorescens is part of the large Pseudomonas genus. P.fluorescens is a gram negative bacterium which is motile thanks to its flagellas. The bacterium has a rod like shape with many flagellas and grows in aerobic conditions.
These little creatures can be found on soil and soil and water, but they can live on animals and plants as well. In their natural habitat they are found in the form of biofilms or planktonic form.
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| Figure 1: P.fluorescens in the tube received from the supplier, grown on Nutrient agar and conserved in the fridge |
These bacteria can be grown on nutrient medium. The optimal growth temperature varies between 25°C and 30°C. The nutrient medium is composed of nitrogen source in the form of peptone which has to be at a concentration of 0.5%. The vitamins, carbohydrates, salt and other components that promote bacterial growth is furnished by 0.3% beef or yeast extract. 1.5% of agar is needed to obtain a solid medium to which 0.5% sodium chloride (NaCl). Finally we need a add distilled water and the pH should be adjusted to 7.4.
Even though the literature available suggest us to use the nutrient medium, the LBA medium can also be used due to its close ressemblance. To test this we put the P.fluorescens on a LBA medium overnight at 30°C. The results were as expected, the microorganisms had grown where many single colonies could be identified (Figure 2 and 3).
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Figure 2: A culture of P.fluorescens after one day of culture on LBA medium at 30°C
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Figure 3: A culture of P.fluorescens after three days of culture on LBA medium at 30°C
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Even though some strains of the Pseudomonas are pathogenic, our little friend is non-pathogenic and is able to degrade partially pollutants which has led people to look closer into the use of these microorganisms as bioremediants. This not the only studies where P.fluorescens is used, as it is capable of fighting fungal infection in crops, new studies have been looking into the biological disease control character of this bacterium.
When the concentration of iron is low enough, the microbe produces a green pigment which is fluorescent as the name indicates. In order to test the fluorescence of this bacterium, the plate was exposed to a 475 nm wavelength through the Illumatool Tunable Light System.
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| Figure 4: P.fluorescens seen under Illumatool TLS exposed to 475 nm wavelength |
They are indeed fluorescent when exposed to UV light at a certain wavelength.
This organism can be used in several projects such as studying its fluorescence, biocontrol abilities,...
Feeling like this was not enough ? Have a look at these!
https://www.ncbi.nlm.nih.gov/genome?term=txid294%5Borgn%5D
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