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Streptococcus is a genus of gram-positive or spherical bacteria that belongs to the family Streptococcaceae, within the order Lactobacillales (lactic acid bacteria), in the phylum Bacillota. [2] Cell division in streptococci occurs along a single axis, thus when growing they tend to form pairs or chains, which may appear bent or twisted.
The encapsulated, Gram-positive, coccoid bacteria have a distinctive morphology on Gram stain, lancet-shaped diplococci. They have a polysaccharide capsule that acts as a virulence factor for the organism; more than 100 different serotypes are known, and these types differ in virulence, prevalence, and extent of drug resistance.
According to some definitions, the term is used to describe Gram-negative bacteria. [3] [4] According to other definitions, the term also encompasses yeasts. [5] [6] The name spheroplast stems from the fact that after the microbe's cell wall is digested, membrane tension causes the cell to acquire a characteristic spherical shape. [4]
Later, in 1946, Lancefield described the serologic classification of S. pyogenes isolates based on components of their surface pili (known as the T-antigen) [13] which are used by bacteria to attach to host cells. [14] As of 2016, a total of 120 M proteins are identified. These M proteins are encoded by 234 types emm gene with greater than ...
Sucrose is the only sugar that bacteria can use to form this sticky polysaccharide. [1] However, other sugars—glucose, fructose, lactose—can also be digested by S. mutans, but they produce lactic acid as an end product. The combination of plaque and acid leads to dental decay. [12]
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]
Reproduction of T. namibiensis occurs on a single plane; the cocci (a spherical bacterial cell) divide into a diplococcus or streptococcus arrangement. [ 13 ] [ 42 ] A diplococcus is a pair of cocci cells that can form chains, and streptococcus is a grape-like cluster of cells. [ 43 ]
Staphylococcus is a genus of Gram-positive bacteria in the family Staphylococcaceae from the order Bacillales. Under the microscope, they appear spherical , and form in grape-like clusters. Staphylococcus species are facultative anaerobic organisms (capable of growth both aerobically and anaerobically).