Binomial name- Pseudomonas aeruginosa
- Kingdom- Bacteria
- Phylum- Proteobacteria
- Class- Gamma Proteobacteria
- Order- Pseudomonadales
- Family- Pseudomonadaceae
- Genus- Pseudomonas
- Species- P. aeroginosa
Description and significance
P. aeruginosa is a rod shaped bacterium that is gram negative. On the original media plate, the bacteria appeared light brown and overtook the quadrants where it was streaked. While there were distinct colonies that could be deciphered, they had spread-out, irregular edges. P. aeruginosa can be found on skin surfaces and is fairly prolific in soil and man-made environments (including hospitals).
Cell structure and metabolism
P. Aeruginosa is widely considered as a facultative anaerobe, though officially it is aerobic. As aforementioned, P. aeruginosa is gram negative and is motile using a single polar flagellum (4). P. aeruginosa thrives in moist environments such as soil and is salt tolerant, which is why it can live on skin.
The soil sample containing P. aeruginosa was taken from the soil in Dripping Springs, Texas, with the approximate location 30.1919° N, 98.0853° W. P. aeruginosa is a free living bacteria that is found in many different environments; including normal human flora, soil, and other environments such as water reservoirs, and hospital surfaces. P. aeruginosa was studied in a zero-gravity environment in space, and adapted its biofilm structure to a column-like shape that has not been observed on earth (1).
P. aeruginosa is considered an opportunistic pathogen that is often found in hospital or long-term care facilities. The microbe can often infect the blood or urinary tract, and is frequently a danger to burn victims or patients with open wounds. The biofilms can cause chronic infections because the bacteria in this enhanced environment does not respond well to antibiotics (3). Primarily in nosocomial settings, P. aeruginosa is spread by improper hand washing (3).
Lab Test Results
A series lab tests were conducted on the bacteria in the soil sample for identification purposes. Notable results are recorded below:
- Urea test- negative result (light pink color)
- SIM test- Negative result for sulfur (black line shown on top of test)
- Turbidity test- Positive result for motility
- Nitrate test- Reddish-pink result positive for nitrate
- Citrate test- Royal blue result in slant broth- positive result
- EMB (Eosin Methylene Blue Agar) test- no results available
- HE (Hektoen Enteric Agar) test- no growth seen (blue growth seen on other cultures of P. aeruginosa in class)
- MAC (MacConkey Agar) test- clear result, no growth seen
- Blood Agar test- large black growth in agar, slight clearing (Beta result- complete hemolysis)
- PEA (Penylethyl Alcohol Agar) test- slight colorless growth from inoculating line, inhibited growth (gram negative organism)
- Mannitol Salt Agar (MSA) test- no growth noted in pink broth, no yellow for fermentation
- Bile Esculin test- a few black dots of growth on slant broth- negative for bile
- Salt Tolerance test- not turbid, clear broth- negative for growth.
- Oxidase test- negative reaction initially, even when reagent was applied there was no change on color
- Genetic sequencing- results for the gene sequence were examined through website (blast.ncbi.nim.nih.gov/) and with high probability were identified as P. aeruginosa.
1. Kim W et al. (29 April 2013). Beloin, Christophe, ed. "Spaceflight Promotes Biofilm Formation by Pseudomonas aeruginosa". Plos One 8 (4): e6237. doi:10.1371/journal.pone.0062437. Retrieved 5 July 2013.
2. Botzenhardt, K., and Doring, G. Ecology and epidemiology of Pseudomonas aeruginosa. Pseudomonas aeruginosa as an Opportunistic Pathogen. 1993. p. 1-7.