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Colonial morphology of various specimens of Pseudomonas aeruginosa, including mucoid types. In microbiology, colonial morphology refers to the visual appearance of bacterial or fungal colonies on an agar plate. Examining colonial morphology is the first step in the identification of an unknown microbe.
For instance, the bacterial colony is a cluster of identical cells (clones). These colonies often form and grow on the surface of (or within) a solid medium, usually derived from a single parent cell. [2] Colonies, in the context of development, may be composed of two or more unitary (or solitary) organisms or be modular organisms.
The formation of patterns in the growth of bacterial colonies has extensively been studied experimentally. Resulting morphologies appear to depend on the growth conditions. They include well known morphologies such as dense branched morphology (DBM) or diffusion-limited aggregation (DLA), but much complex patterns and temporal behaviour can be fou
The colony morphology itself also displays several varieties. The main two types are large, smooth, with a flat edge and elevated center and small, rough, and convex. [83] A third type, mucoid, can also be found. The large colony can typically be found in clinal settings while the small is found in nature. [83]
Spiral bacteria are another major bacterial cell morphology. [2] [30] [31] [32] Spiral bacteria can be sub-classified as spirilla, spirochetes, or vibrios based on the number of twists per cell, cell thickness, cell flexibility, and motility. [33] Bacteria are known to evolve specific traits to survive in their ideal environment. [34]
B. cereus colonies on MYP have a violet-red background and are surrounded by a zone of egg-yolk precipitate. [27] Below is a list of differential techniques and results that can help to identify B. cereus from other bacteria and Bacillus species. [28] Anaerobic growth: Positive; Voges Proskauer test: Positive; Acid produced from D-glucose: Positive
Additionally, colonies which exhibit characteristics typical of Bacillus bacteria can be selected from a culture of an environmental sample which has been significantly diluted following heat shock or hot air drying to select potential Bacillus bacteria for testing. [18] Cultured colonies are usually large, spreading, and irregularly shaped.
Colonies tend to be cream-colored, but will turn red in the presence of iron in media, most likely as a result of pulcherrimin. [ 6 ] [ 9 ] B. licheniformis is found in a wide variety of environments, but especially in soil and in the feathers of birds, where B. licheniformis degrades β-keratin .