Oxidase test in the context of "Pasteurella"

Streptococcus, from Ancient Greek στρεπτός (streptós), meaning "twisted", and κόκκος (kókkos), meaning "grain", is a genus of gram-positive spherical bacteria that belongs to the family Streptococcaceae, within the order Lactobacillales (lactic acid bacteria), in the phylum Bacillota. 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. This differs from staphylococci, which divide along multiple axes, thereby generating irregular, grape-like clusters of cells. Most streptococci are oxidase-negative and catalase-negative, and many are facultative anaerobes (capable of growth both aerobically and anaerobically).

The term was coined in 1877 by Viennese surgeon Albert Theodor Billroth (1829–1894), from Ancient Greek στρεπτός (streptós), meaning "twisted", and κόκκος (kókkos), meaning "grain". In 1984, many bacteria formerly grouped in the genus Streptococcus were separated out into the genera Enterococcus and Lactococcus. Currently, over 50 species are recognised in this genus. This genus has been found to be part of the salivary microbiome.

Klebsiella is a genus of Gram-negative, oxidase-negative, rod-shaped bacteria with a prominent polysaccharide-based capsule.

Klebsiella is named after German-Swiss microbiologist Edwin Klebs (1834–1913). Carl Friedlander described Klebsiella bacillus which is why it was termed Friedlander bacillus for many years. The species of Klebsiella are all gram-negative and usually non-motile. They tend to be shorter and thicker when compared to others in the family Enterobacteriaceae.

Aliivibrio fischeri (formerly Vibrio fischeri) is a non-pathogenic, Gram-negative, rod-shaped bacterium found globally in marine environments. This bacterium grows most effectively in water with a salt concentration at around 20g/L, and at temperatures between 24 and 28°C. Free-living A. fischeri cells survive on decaying organic matter. It is heterotrophic, oxidase-positive, and motile by means of a tuft of polar flagella. A. fischeri is found predominantly in symbiosis with various marine animals, such as the Hawaiian bobtail squid. A. fischeri also has bioluminescent properties controlled by the lux operon. The bacterium is a key research organism for examination of bacterial-animal symbiosis, microbial bioluminescence, and quorum sensing. It is named after Bernhard Fischer, a German microbiologist.

Aliivibrio fischeri is in the family Vibrionaceae. This family of bacteria tend to have adaptable metabolisms that can adjust to diverse circumstances. This flexibility may contribute to A. fischeri's ability to survive both alone and in symbiotic relationships.