Introduction of Colony Morphology
Table of Contents
Colony morphology of bacteria is the most common diagnostic method in bacteriology for the isolation and identification of bacteria on the basis of phenotypic characteristics on solid medium for the color, shape, surfaces, size, elevation, edges, opacity, and consistency.
Common Colony Characteristics of Bacteria
Colony morphology of bacteria on the basis of the following features:
- Margin or edge
- Surface appearance
It is of three types on the basis of the diameter of the colony.
Large: Diameter of colony larger than 1 mm
Medium: 1 mm in diameter.
Small: Less than 1 mm in diameter.
It is of the following types-
Elevation of the colony is of the following types-
The margin of the colony is further divided into
The color of the colony is the following types-
- Red etc.
The surface appearance of the colony may be-
Colony density is the ability to see through the colony. On this basis is of following types-
- Opaque: It can not see through the colony.
- Transparent: It can see through the colony.
- Translucent: It can only see with light shining through.
Consistency of the colony is best observed by picking up a colony with a loop or needle. It is of the following types-
- Butyrous (buttery)
- Viscid (sticky)
- Friable (Crumbles easily)
- Membranous (pliable)
It is best observable in 5 % sheep blood agar. It is of three types-
- Alpha (α) hemolysis
- Beta (β) hemolysis
- Gamma (γ) hemolysis
According to smell, it is of the following types-
Some bacteria produce pigments and are of the following types-
- Golden yellow (Staphylococcus aureus)
- Lemmon yellow (Micrococcus luteus)
- Prodigiosin( pink/red/ magenta): e.g. Serratia marcescens
- Pyocyanin (bluish-green) e.g. Pseudomonas aeruginosa
- Pyoverdin/fluorescein (greenish-yellow) e.g. Pseudomonas aeruginosa
- Pyomelanin (brown to black pigment) e.g. Pseudomonas aeruginosa
- Pyorubrin (red): e.g. Pseudomonas aeruginosa
Colony Morphology of Bacteria-Related Photos
Small size colony of bacteria
Large size colony of bacteria
Beta-hemolytic colony of streptococci on blood agar
Prodigiosin pigment of Serratia marcescens
Pyoverdin Pigment of Pseudomonas aeruginosa on Muller-Hinton agar
Pyocyanin and pyorubrin pigments of Pseudomonas aeruginosa
Micrococcus luteus yellow color colony on nutrient agar
Micrococcus roseus red colony on a nutrient agar plate
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