Morphology & Culture Characteristics of Pseudomonas aeruginosa

MORPHOLOGY AND CULTURE CHARACTERISTICS OF PSEUDOMONAS AERUGINOSA (P. AERUGUNOSA)

MORPHOLOGY OF PSEUDOMONAS AERUGINOSA (P. AERUGINOSA)

ShapePseudomonas aeruginosa is a Slender, rod shape (bacillus) bacterium.

Size – The size of P. aeruginosa is about 1.5–3 mm × 0.5 mm (micrometer).

Arrangement Of CellsPseudomonas aeruginosa is arranged singly or in pairs.

MotilityPseudomonas aeruginosa is an actively motile bacterium.

pseudomonas aeruginosa gram staining - gram negative pseudomonas aeruginosa
MICROSCOPIC VIEW OF PSEUDOMONAS AERUGINOSA (GRAM STAINED SMEAR)

FlagellaP. aeruginosa is a flagellated bacterium with a polar flagellum, arranged in an amphitrichous manner.

Spores – The Pseudomonas aeruginosa is a non – sporing bacterium.

CapsuleP. aeruginosa is a non – capsulated bacterium but some strains posses slime layer.

Gram Staining Reaction – Pseudomonas aeruginosa is a Gram -ve (Negative) bacterium.



CULTURE REQUIREMENTS OF PSEUDOMONAS AERUGINOSA (P. AERUGINOSA)

Special requirementsPseudomonas aeruginosa or P. aeruginosa have no complex nutritional requirements and readily grow in an ordinary media like Nutrient Agar medium (NAM). Commonly the NAM & MacConkey Agar medium is used for the cultivation of Pseudomonas aeruginosa in Laboratory.

 Optimum temperaturePseudomonas aeruginosa has a wide range of temperature that is from 4–40°C but the optimum temperature for most of the strains is 37°C and usually cultivated at this temperature in laboratories.

⇒ Optimum pHP. aeruginosa can survive at 5.6– 9.0 pH but the maximum growth observed in between 6.6-7.6 i.e. around slightly acidic to slightly alkaline pH. Also, the pH requirements vary as per the strain of Escherichia col.

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MORPHOLOGY AND CULTURE CHARACTERISTICS OF NEISSERIA GONORRHOEAE (GONOCOCCUS OR GONOCOCCI)

⇒ Oxygen requirementsPseudomonas aeruginosa (P. aeruginosa) is an obligate aerobic bacterium i.e. grows only in the presence of oxygen.

⇒ There are various culture media used for the cultivation of Pseudomonas aeruginosa  (P. aeruginosa) in the laboratory and most commonly the Nutrient Agar medium and MacConkey Agar medium is used, the other media are as follows –

The Cetrimide Agar medium which is a selective medium for the P. aeruginosa and other species of Pseudomonas consists of a key component Cetrimide which inhibits the growth of many bacteria including gram-positive bacteria & Normal flora while allowing the growth of Pseudomonas species and especially the Pseudomonas aeruginosa.

CULTURE CHARACTERISTICS OF PSEUDOMONAS AERUGINOSA (P. AERUGINOSA)

Cultural CharacteristicsNutrient Agar Medium (NAM)Cetrimide Agar mediumMacConkey Agar mediumBlood Agar Medium
ShapeIrregularCircularCircularIrregularly edged circular
Size2-4 mm1-3 mm2-3 mm2-4 mm
ElevationLow ConvexLow ConvexLow ConvexFlat
SurfaceSmooth (fresh isolation) ; Mucoid (When slime layer is formed)Smooth (fresh isolation) ; Mucoid (When slime layer is formed)Smooth (fresh isolation) ; Mucoid (When slime layer is formed)Smooth (fresh isolation) ; Mucoid (When slime layer is formed)
ColorGreenish blue (due to pigment production)Greenish blue (due to pigment production)ColorlessGreyish white
StructureTranslucent –OpaqueOpaqueTransparentTranslucent –Opaque
Hemolysis---------------β-Hemolysis (in some strains)

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MORPHOLOGY AND CULTURE CHARACTERISTICS OF PROTEUS VULGARIS (PR. VULGARIS)

In liquid culture media like Trypticase soy broth or Nutrient broth, the growth of the bacterium occurs as a dense turbidity in the broth medium with a surface pellicle which is further analyzed for the morphology (under the microscope), gram reaction, biochemical tests, and Pseudomonas aeruginosa specific tests.

In Blood Agar medium, some of the strains show beta hemolysis, especially which are isolated from the pathologic conditions whereas those which are isolated from normal persons may or may not show hemolysis on blood agar. It produces Large, flat and irregularly edged circular colonies.

pseudomonas aeruginosa on blood agar - p aeruginosa on blood agar medium
CULTURE OF PSEUDOMONAS AERUGINOSA ON BLOOD AGAR MEDIUM

In an ordinary medium like Nutrient Agar medium, Pseudomonas aeruginosa produces a characteristic sweetish odor or a distinctive musty or earthy smell in the medium.



In MacConkey Agar medium, the colonies of Pseudomonas aeruginosa are Colorless due to the lack of lactose fermentation which is of great importance in differentiating P. aeruginosa from other Bacteria present in the specimen, especially from Gram-positive bacteria, E. coli & Klebsiella species which are Lactose fermentors and gives pink colored colonies on MacConkey agar medium.

Pseudomonas aeruginosa on macconkey agar medium - p aeruginosa on macconkey agar
CULTURE OF PSEUDOMONAS AERUGINOSA ON MACCONKEY AGAR MEDIUM

In Cetrimide Agar medium, the selective medium for Pseudomonas aeruginosa, colonies are Medium sized & irregular growth is observed due to the swarming of the bacterium. The pigment production is enhanced and diffused in the medium imparting characteristic greenish-blue coloration to the medium.

Pseudomonas aeruginosa on cetrimide agar medium - p aeruginosa on cetrimide agar
CULTURE OF PSEUDOMONAS AERUGINOSA ON CETRIMIDE AGAR MEDIUM

PIGMENT PRODUCTION IN THE CULTURE OF PSEUDOMONAS AERUGINOSA

In the culture medium, P. aeruginosa produces mainly 4 types of pigments which diffuse out into the surrounding medium and imparts a characteristic color to the medium indicating the suspected growth of Pseudomonas aeruginosa. These are described as below:

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MORPHOLOGY AND CULTURE CHARACTERISTICS OF KLEBSIELLA PNEUMONIAE (K. PNEUMONIAE)


NAME OF THE PIGMENTCOLOR OF THE PIGMENT
PyocyaninBluish-Green
FluoresceinGreenish-Yellow
PyorubicinReddish-Brown
PyomelaninBrown to black

Of the 4 types of Pigments, only the Pyocyanin is important from the diagnostic point of view as Pyocyanin is the only pigment that is not produced by any other species of Pseudomonas but only by the Pseudomonas aeruginosa imparting characteristic color to the medium representing Pseudomonas aeruginosa growth in the medium.

That’s all about the Morphology & Culture characteristics of Pseudomonas aeruginosa



Further Reading:

Cetrimide Agar medium – Hardy diagnostics

Pseudomonas aeruginosa on Cetrimide agar – Fishersci

Culture requirements P. aeruginosa – Textbook of Bacteriology

P. aeruginosa on Blood agar – Veterian key

Culture characteristics of Pseudomonas – Slide Player

Pseudomonas aeruginosa – Wikipedia

Pseudomonas aeruginosa – Microbewiki

Pseudomonas aeruginosa structure – hhmglobal

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