MORPHOLOGY OF PROTEUS VULGARIS (PR. VULGARIS)
Shape – Proteus Vulgaris is a short, straight rod shape (bacillus) bacterium.
Size – The size of Proteus Vulgaris is about 1–3 µm × 0.5 µm (micrometer).
Arrangement Of Cells – Pr. vulgaris is arranged singly, in pairs, or in short chains and sometimes in clusters.
Motility – Proteus Vulgaris is an actively motile bacterium and well known for the swarming growth on an ordinary medium like NAM.
Flagella – Pr. Vulgaris is a flagellated bacterium with a Peritrichous flagella arrangement i.e. flagella are present all over the surface of the bacterium.
Spores – The Proteus Vulgaris is a non–sporing bacterium.
Capsule – Capsules are not present in Proteus Vulgaris.
Gram Staining Reaction – Proteus Vulgaris is a Gram -ve (Negative) bacterium.
CULTURE REQUIREMENTS OF PROTEUS VULGARIS (PR. VULGARIS)
⇒ Special requirements – Proteus Vulgaris 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 Proteus Vulgaris in Laboratory.
⇒ Optimum temperature – Proteus Vulgaris ranges from 10–43°C but the optimum temperature for most of the strains is 37°C and usually cultivated at this temperature in laboratories.
⇒ Optimum pH – Pr. vulgaris can survive alkaline pH as well as acidic pH ranging from 4.0 – 11.0 and the maximum growth of the organism is observed at 6.0 i.e. neutral pH. Also, the pH requirement varies as per the strain of Proteus vulgaris.
⇒ Oxygen requirements – Proteus Vulgaris (Pr. vulgaris) is an aerobic bacterium i.e. grow best in the presence of oxygen and it is also a Facultative anaerobic organism i.e. can grow in the low oxygen environment.
⇒ There are various culture media used for the cultivation of Proteus Vulgaris in the laboratory and most commonly the Nutrient Agar medium and MacConkey Agar medium is used, the other media are as follows –
- Columbia Horse Blood Agar medium
- Sheep Blood Agar medium
- Xylose Lysine Dextrose (XLD) Agar medium
- Eosin Methylene Blue Agar (EMB Agar) Medium.
- The liquid medium (Nutrient Broth medium, TSB medium, etc.).
⇒ The Eosin Methylene Blue Agar (EMB Agar) medium can also be used for the cultivation of Proteus Vulgaris in laboratory contains Eosin dye and Methylene Blue dye which inhibits the growth of many gram-positive bacteria, inhibits the growth of Shigella and Salmonella species and supports the growth of Proteus Vulgaris.
CULTURE CHARACTERISTICS OF PROTEUS VULGARIS (PR. VULGARIS)
Cultural Characteristics Nutrient Agar Medium (NAM) MacConkey Agar medium Blood Agar Medium EMB Agar medium
Shape Irregular (due to swarming) Circular Irregular (due to swarming) Circular
Size 1-2 mm 2-3 mm 1-2 mm 2-3 mm
Elevation Effuse Low Convex Effuse Effuse
Surface Glistening Smooth Glistening Glistening
Color Greyish white Colorless or Pale colored Greyish white Colorless
Structure Translucent Transparent Translucent –Opaque Transparent
Hemolysis ----- ----- γ-Hemolysis (Non-hemolytic) -----
In Liquid culture media like Trypticase soy broth or Nutrient broth & Peptone Water, the growth of the bacterium occurs as a uniform turbidity in the broth medium with a powdery deposit and Ammoniacal smell which is further analyzed for the morphology (under the microscope), gram reaction, biochemical tests, and Proteus Vulgaris specific tests.
In Blood Agar medium, the Proteus Vulgaris exhibits the swarming and the growth occurs in the whole media plate. Usually, it produces non-hemolytic growth on Blood agar plate but some of the strains are β-Hemolytic.
In MacConkey Agar medium, the colonies of Proteus Vulgaris are pale or colorless due to lack of lactose fermentation which is of great importance in differentiating Pr. vulgaris from other Bacteria present in the specimen, especially from Gram-positive bacteria (S. aureus), E.coli & Klebsiella species which are lactose fermentors and gives Pink colored colonies on MacConkey agar medium. Moreover, the swarming is inhibited in the MacConkey Agar medium due to the presence of Bile Salts.
The Swarming of Proteus vulgaris is best observed in Nutrient Agar medium, covering the whole plate. The colonies are small, glistening and usually, the growth is irregular due to swarming.
The swarming of Proteus can be inhibited by
- Increasing the concentration of agar from 1-2% to 6%.
- Incorporation of sodium azide, boric acid, or chloral hydrate in the medium.
- The addition of growth inhibitors like sulphonamides to the medium.
- Addition of Teepol (a surface active agent) which is present in Teepol Lactose agar medium.
- The presence of Bile salts in the medium, present in MacConkey agar or DCA medium.
That’s all about the Morphology & Culture Characteristics of Proteus vulgaris