Soil Unknown: P. aeruginosa

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Classification

Domain	Bacteria
Phylum	Proteobacteria
Class	Gammaproteobacteria
Order	Pseudomonadales
Family	Pseudomonadaceae
Genus	Pseudomonas
Species Group	Pseudomonas aeruginosa group
Species	Pseudomonas aeruginosa

Species

NCBI: Taxonomy

Genus species:	Pseudomonas aeruginosa

Habitat Information

The organism was isolated from 1 gram of a soil sample gathered from a park in the Barton Creek Landing complex in Travis County. In general, P. aeruginosa can be found in soil, decaying organic matter, and a variety of moist environments, including swimming pools, hot tubs, sponges, washcloths, and contact lens solutions (1).

Date: September 6, 2017
Humidity: 37%
Air Temp: 82 F
24 Hr Rainfall: 0
Pressure: 1017.3 mb at sea level
Wind 4am: 2.06 mph
Wind 4pm: 2.77mph
Solar Radiation: 22.49 mJ/m2

Description and Significance

Appearance

Gram Stain: Gram Negative Rods

At the cellular level, P. aeruginosa is a Gram Negative bacilli. At the colonial level, P. aeruginosa colonies appear to be of small to moderate, irregular, pulvinate and smooth. When incubated at 30 degrees celsius, the colonies have a small amount of orange pigmentation. When incubated at 37 degrees celsius, the colonies have gray pigmentation, as well as blue-green extracellular pigmentation:

30 degree incubation of Pseudomonas aeruginosa.

37 degree incubation of Pseudomonas aeruginosa.

Antimicrobial Activity

A study published in the Annals of Clinical Microbiology and Antimicrobials concluded that P. aeruginosa-derived extracellular compounds such as phenazines have inhibitory effects against MRSA. A synergic effect was observed when combined with silver nanoparticles produced by Fusarium oxysporum (2).

P. aeruginosa-derived phenazine and MRSA.

Strain PR3 of P. aeruginosa has been found to have antifungal properties, inhibiting both Candida albicans and rice blast fungus (3.)

Significance of organism

Psuedomonas aeruginosa is a rare opportunist because it cannot penetrate the intact, natural defenses of the skin. Susceptible potential victims include burn victims, cancer patients, and immunocompromised patients. Those with cystic fibrosis have a higher risk of acquiring a P. aeruginosa lung infection.

P. aeruginosa is the most common microorganism seen in burn victims, and the microbe typically grows underneath the scab-like crust that naturally forms over a severe burn. Once established, it kills cells and destroys tissues. Large infections can be diagnosed due to the microbe's blue-green pyocyanin pigment. If P. aeruginosa invades the bloodstream, severe symptoms including fever, chills and shock can result

In general, a penicillin and an aminoglycoside are simultaneously used to treat P. aeruginosa infections. To treat a P. aeruginosa infection in a burn patient, debridement and administration of antimicrobial drugs are necessary. (1)

Genome Structure

At 6.3 million base pairs [1]- coding for 5,570 genes - this is the largest bacterial genome sequenced primarily due to its complexity, rather than any significant number of gene duplications. Fluorescent microscopy has verified that chromosomes within this bacterium are located longitudinally with replication forks located primarily in the middle of the cell. In addition, DNA supercoiling (over- or under-winding of a DNA strand) allows these chromosomes to fit into the nucleoid within the cell - this particular organization can strongly affect DNA metabolism and even gene expression.

S Ribosomal sequence: Group_2R-ACC_primer_-_reverse_D07.ab1

NNNNNNANNNNNNNCNNCCTGTNACTCTGTCCCCGAAGGGAAAGCCCTATCTCTAGGGTTGTCAGAGGATGTCAAGACCT GGTAAGGTTCTTCGCGTTGCTTCGAATTAAACCACATGCTCCACCGCTTGTGCGGGCCCCCGTCAATTCCTTTGAGTTTC AGTCTTGCGACCGTACTCCCCAGGCGGAGTGCTTAATGCGTTAGCTGCAGCACTAAGGGGCGGAAACCCCCTAACACTTA GCACTCATCGTTTACGGCGTGGACTACCAGGGTATCTAATCCTGTTCGCTCCCCACGCTTTCGCTCCTCAGCGTCAGTTA CAGACCAGAGAGTCGCCTTCGCCACTGGTGTTCCTCCACATCTCTACGCATTTCACCGCTACACGTGGAATTCCACTCTC CTCTTCTGCACTCAAGTTTCCCAGTTTCCAATGACCCTCCCCGGTTGAGCCGGGGGCTTTCACATCAGACTTAAGAAACC GCCTGCGAGCCCTTTACGCCCAATAATTCCGGACAACGCTTGCCACCTACGTATTACCGCGGCTGCTGGCACGTAGTTAG CCGTGGCTTTCTGGTTAGGTACCGTCAAGGTGCGAGCAGTTACTCTCGCACTTGTTCTTCCCTAACAACAGAGCTTTACG ATCCGAAAACCTTCATCACTCACGCGGCGTTGCTCCGTCAGACTTTCGTCCATTGCGGAAGATTCCCTACTGCTGCCTCC NNNNNNNNACTGNCCNNNNNNTTTNCNA

Cell Structure, Metabolism and Life Cycle

P. aeruginosa is a Gram negative, rod-shaped bacterium that is typically found in water and soil environments with an ability to infect a variety of hosts, including plants, invertebrates as well as humans. Given its adaptability, it is considered one of the top three opportunistic pathogens and is known for a wide range of virulence factors. It requires very little in regards to nutrition and while it prefers to grow in the presence of oxygen, it is a facultative anaerobe that can utilize nitrate (NO3) as an electron acceptor. P. aeruginosa has capsules, produces biofilms and is motile using a single, polar flagellum [2]
which adds to its virulence allowing it to evade the body’s immune response. In addition, it utilizes pili and protease enzymes to attach to epithelial cells while also produceing extracellular toxins Exoenzyme S (induces apoptosis) and Exotoxin A (most toxic virulence factor) to invade host cells.

Physiology and Pathogenesis

Biochemical characteristics and Enzymes Made

Positive Motility Test

Negative Phenylalanine Deaminase Test

Positive Catalase Test

Negative MacConkey Agar Test

Negative Hektoen Enteric Agar Test

Weak Positive Eosin Methylene Blue Test. However, multiple other tests showed that lactose is not fermented by P. aeruginosa.

Gram Stain	Negative
Motility Test	Positive
Gelatinase Test	Positive: produces gelatinase enzyme
DNA Hydrolysis Test	Negative: no deoxyribonuclease enzyme
Lipid Hydrolysis Test	Positive: Presence of Lipase enzyme
Phenol Red Glucose	Orange (shows some glucose fermentation, though P .aeruginosa does not ferment glucose.)
Phenol Red Sucrose	Red: no Sucrose fermentation
Phenol Red Lactose	Red: no Lactose fermentation.
Starch Hydrolysis	Negative: no Amylase enzyme
Casein Hydrolysis	Positive: Casease enzyme
SIM Medium	Positive for Motility and Sulfur Reduction. Indole production: negative
TSI Test	K/NC, H2S: Negative fermentation, Positive H2S reduction
Citrate Test	Positive: Citrate as a carbon source
Urease Test	Negative: no Urease enzyme
MR-VP Tests	Negative MR: does not ferment glucose. Negative VP: does not use butylene glycol pathway
Nitrate Reduction Test	Positive: denitrification took place
Hektoen Enteric Agar	Negative: Non-Lactose Fermenting (NLF)
MacConkey Agar	Negative: NLF
Oxidase Test	Negative: does not produce cytochrome oxidase
Eosin Methylene Blue Agar	Weak positive: Indicates weak lactose fermentation, though P .aeruginosa does not ferment lactose.
Phenylalanine Deaminase	Negative: no Deaminase enzyme
Decarboxylation Test: Arganine	Positive: produces arginine decarboxylase
Decarboxylation Test: Lysine	Negative: does not produce lysine decarboxylase
Decarboxylation Test: Ornithine	Negative: does not produce ornithine decarboxylase
Catalase Test	Positive: Catalase enzyme
Blood Agar	Alpha hydrolysis: partial hemolysis
Bacitracin & Optichin Susceptibility	Negative: Neither inhibited growth
Phenylethyl Alcohol Agar	Very slow growth: not a Gram Positive organism
Mannitol Salt Agar	Negative: Inhibited by salt
6.5% Salt Tolerance Test	Negative: Inhibited by salt
Bile Esculin Test	Negative: does not hydrolyze esculin

Hosts

• Humans - those most susceptible include burn victims, cancer patients, and immunocompromised patients. Cystic fibrosis patients have a higher risk of lung infection.(1)
• Animals - similar susceptibility patterns to humans. The most commonly colonized sites include wet or moist anatomic areas like the gut and respiratory tract, along with chronically wet areas of fur. (5)
• Plants - certain strains are capable of infecting plant roots. A study published in Plant Physiology details two P.aeruginosa strains that infect the roots of Arabidopsis and sweet basil, and are capable of causing plant mortality. (6)

Virulence factors

• Fimbriae and adhesions aid in attachment to host, as well as enabling biofilm formation.
• Capsule helps shield the bacteria from phagocytosis, and also aids in bacterial attachment and biofilm formation.
• Neuraminidase enzyme helps bacteria attach to host.
• Elastase enzyme breaks down IgA, IgG, degrades complement components, and breaks down elastic fiber.
• Lipid A component can trigger fever, blood clotting, inflammation, or shock.
• Exotoxin A and exoenzyme S inhibit eukaryotic protein synthesis.
• Pyocyanin pigment triggers the formation of reactive forms of oxygen, which damages host cells (1).

Patient Symptoms

• Blue-green color where the bacterium is growing
• With bacteremia: fever, blood clotting, inflammation and shock are possible
• With lung infections: breathlessness, coughing, wheezing, rapid breathing, and weight loss (1)

References

1. Bauman, R. W. (2015) Microbiology with Diseases by Body System, pp. 567, 570. Glenview, IL: Pearson.
2. Cardozo, V., Oliveira, A.,Nishio, E. Antibacterial activity of extracellular compounds produced by a Pseudomonas strain against methicillin-resistant Staphylococcus aureus (MRSA) strains. Annals of Clinical Microbiology and Antimicrobials. 2013. Volume 12:12.
3. Bajpai, Vivek K.; Shin, Seung Yong; Kim, Hak Ryul; Kang, Sun Chul. 2008. Anti-fungal action of bioconverted eicosapentaenoic acid (bEPA) against plant pathogens. Industrial Crops and Products. 27(1): 136-141.
4. "Complete genome sequence of Pseudomonas aeruginosa PAO1, an opportunistic pathogen". 2000. [3]
5. Psuedomonas aeruginosa Technical Sheet. Charles River Laboratories, 2017.
6.Walker, T., Bais, H., Deziel, E., and Schweizer, H., ''Pseudomonas aerutinosa-plant root interactions. Pathogenicity, biofilm formation, and root exudation. Plant Physiology'. 2004. Volume 134. p. 320 - 331.
7. Vallet-Gely, Isabelle. "Chromosomal Organization and Segregation in Pseudomonas aeruginosa". 2013. [4]
8. Weigel, Christoph. "Chromosome Organization the Pseudomonas Way, Part 1". 2014. [5]

Author

Page authored by Leila Adell and Katie Krause, students of Prof. Kristine Hollingsworth at Austin Community College.