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A colony is defined as a visible mass of microorganisms all originating from a single mother cell, therefore a colony constitutes a clone of bacteria all genetically alike. In the identification of bacteria and fungi much weight is placed on how the organism grows in or on media.
- Colony Shape
- Size of The Bacterial Colony
- Appearance of The Colony Surface
- Consistency/Texture
- Color of The Colonies
- The Opacity of The Bacterial Colony
- Some Important Terminologies
It includes the form, elevation, and margin of the bacterial colony. Form of the bacterial colony:The form refers to the shape of the colony. These four forms represent the most common colony shapes you are likely to encounter. 1. circular, 2. irregular, 3. filamentous, and 4. rhizoid Elevation of the bacterial colony:It gives information about how...
The size of the colony can be a useful characteristic for identification. The diameter of a representative colony may be measured in millimeters or described in relative terms such as pinpoint, small, medium, and large. Tiny colonies are also referred to as punctiform(pin-point). Colonies larger than about 5 mm are likely to be motile organisms. Pu...
Bacterial colonies are frequently shiny and smooth in appearance. Other surface descriptions might be: dull (opposite of glistening), veined, rough, wrinkled (or shriveled), or glistening. Bacillus species give dry, wrinkled colonies. Pseudomonas stutzerialso gives similar-appearing wrinkled colonies.
Several terms that may be appropriate for describing the texture or consistency of bacterial growth are: dry, moist, viscid (sticks to loop, hard to get off), brittle/friable (dry, breaks apart), mucoid (sticky, mucus-like).
Some bacteria produce pigment when they grow in the medium, e.g., green pigment produces by Pseudomonas aeruginosa, buff-colored colonies of Mycobacterium tuberculosis in L.J medium, and red-colored colonies of Serratia marcescens.
The opacity of a bacterial colony can be described as transparent (clear), opaque (not transparent or clear), translucent (almost clear, but distorted vision–like looking through frosted glass), or iridescent (changing colors in reflected light). A pinpoint translucent β-hemolytic colonies on blood agar is most probably a Streptococcus species. Sta...
Draughtsman colonies Young colonies of Streptococcus pneumoniae (pneumococci)have raised centers, but as the culture ages, they become flattened, with a depressed central part and raised edges giving them a ringed appearance also known as ‘draughtsman colonies’. References 1. Forbes, S., Sahm, D. F., & Weissfeld, A. S. (2002). Bailey & Scott’s Diag...
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Nov 19, 2011 · Classical microbiology uses both gross and microscopic morphology to identify microbes. Gross morphology includes colony shape, size, and surface features (Fig. 2.1). For example, Bacillus atropheus strain globigii produces an orange-pigmented colony on tryptic soy agar but produces small white colonies on other media. The structures assigned ...
- Joany Jackman
- 2012
- 10.1007/978-1-60327-219-3_2
Nov 21, 2023 · A bacterial colony is a mass of bacterial cells that have grown from a single mother cell on a solid agar medium. Binary fission gives rise to many bacteria. A...
Jul 21, 2021 · Definition noun, plural: colonies (biology) Several individual organisms (especially of the same species) living together in close association. (cell culture) A cluster of identical cells (clones) on the surface of (or within) a solid medium, usually derived from a single parent cell, as in bacterial colony. Supplement
Dec 17, 2022 · A colony is a macroscopically visible population of cells growing on solid media, and that arises from a single cell; and microorganisms (particularly bacteria and fungi) are presumptively recognized on solid agar media or plates based on some unique growth features which they express on such growth media ( Figure 1 ).
