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[2]: 518 The microbiologist examines the appearance of the colony, noting specific features such as size, colour, shape, consistency, and opacity. [1]: 165–8 A hand lens or magnifying glass may be used to view colonies in greater detail. [3]: 96 The opacity of a microbial colony can be described as transparent, translucent, or opaque.
Colony-forming units are used to quantify results in many microbiological plating and counting methods, including: The pour plate method wherein the sample is suspended in a Petri dish using molten agar cooled to approximately 40–45 °C (just above the point of solidification to minimize heat-induced cell death).
The colony-forming unit (CFU) is an appropriate description of the colony's origin. In plate counts, colonies are counted, but the count is usually recorded in CFU. Due to the fact that colonies growing on plates may begin as either a single cell or a cluster of cells, CFU allows for a correct description of the cell density.
Blood agar plates (BAPs) contain mammalian blood (usually sheep or horse), typically at a 5–10% concentration. BAPs are enriched, and differential media is used to isolate fastidious organisms and detect hemolytic activity. β-Hemolytic activity will show lysis and complete digestion of red blood cell contents surrounding a colony.
Colonies of Bacillus subtilis on a Petri dish can grow under controlled conditions. By varying agar concentration (which permits the control of the hardness of the medium), and the nutrient concentration, the response of the colony to external stresses can be studied. The different morphologies appear in the following growth conditions:
An agar plate – an example of a bacterial growth medium*: Specifically, it is a streak plate; the orange lines and dots are formed by bacterial colonies.. A growth medium or culture medium is a solid, liquid, or semi-solid designed to support the growth of a population of microorganisms or cells via the process of cell proliferation [1] or small plants like the moss Physcomitrella patens. [2]
Its colonies appear off-white and opaque in color, when grown on agar plates. [7] M. morganii cells are straight rods, about 0.6–0.7 μm in diameter and 1.0–1.7 μm in length. This organism moves by way of peritrichous flagella, but some strains do not form flagella at 30 °C (86 °F).
The agar plates are incubated at 22 °C for 48 hours aerobically. Typical colonies of Brochothrix thermosphacta will grow as straw-colored colonies, 0.5-1.0mm in diameter. Some Pseudomonads can be able to grow on STAA and may be differentiated from Brochothrix thermosphacta by performing an oxidase test .