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It is described using terms like brittle, creamy, sticky and dry. Staphylococci are considered to have a creamy consistency, [1]: 173 while some Neisseria species are sticky, and colonies of diphtheroid bacteria and beta-hemolytic streptococci are typically dry. [1]: 167–8 Bacteria that produce capsules often have a slimy (mucoid) consistency.
Unicellular cyanobacteria have spherical, ovoid, or cylindrical cells that may aggregate into irregular or regular colonies bound together by the mucous matrix secreted during the growth of the colony. [48] Based on the species, the number of cells in each colony may vary from two to several thousand. [47] [1]
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
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.
Bacteria function and reproduce as individual cells, but they can often aggregate in multicellular colonies. [54] Some species such as myxobacteria can aggregate into complex swarming structures, operating as multicellular groups as part of their life cycle , [ 55 ] or form clusters in bacterial colonies such as E.coli .
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 appear pinkish-red with green metallic sheen after 22–24 hours of incubation. These colonies can be confirmed as coliforms if they are inoculated in lauryl tryptose (LST), produce gas, and then inoculated in BGLB. If there is gas production in the BGLB tubes, the test is positive for the presence of coliform bacteria. [18]
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]