''Alkalicoccus'' is a genus of

Gram-Positive In bacteriology, gram-positive bacteria are bacteria that give a positive result in the Gram stain test, which is traditionally used to quickly classify bacteria into two broad categories according to their type of cell wall. Gram-positive bacte ...

rod-shaped bacteria in the family ''

Bacillaceae The Bacillaceae are a family of gram-positive, heterotrophic, rod-shaped bacteria that may produce endospores. Motile members of this family are characterized by peritrichous flagella. Some Bacillaceae are aerobic, while others are facultative ...

'' from the order ''

Bacillales The Bacillales are an order of Gram-positive bacteria, placed within the Bacillota. Representative genera include ''Bacillus'', ''Listeria'' and ''Staphylococcus''. See also * List of bacteria genera * List of bacterial orders This article li ...

.'' The type species of this genus is ''Alkalicoccus saliphilus.'' Members of ''Alkalicoccus'' were previously species (except for the type species, ''Alkalicoccus saliphilus'') belonging to ''

Bacillus ''Bacillus'' (Latin "stick") is a genus of Gram-positive, rod-shaped bacteria, a member of the phylum ''Bacillota'', with 266 named species. The term is also used to describe the shape (rod) of other so-shaped bacteria; and the plural ''Bacilli ...

'', a genus that has been recognized as displaying extensive

polyphyly A polyphyletic group is an assemblage of organisms or other evolving elements that is of mixed evolutionary origin. The term is often applied to groups that share similar features known as homoplasies, which are explained as a result of converg ...

and phylogenetic heterogeneity due to the vague criteria (such as the ability to form endospores in the presence of oxygen) previously used to assign species to this clade. Multiple studies using comparative phylogenetic analyses have been published in an attempt to clarify the evolutionary relationships between ''Bacillus'' species, resulting in the establishment of numerous novel genera such as ''

Alkalihalobacillus ''Alkalihalobacillus'' is a genus of gram-positive or gram-variable rod-shaped bacteria in the family ''Bacillaceae'' from the order ''Bacillales''. The type species of this genus is '' Alkalihalobacillus alcalophilus.'' This genus comprises ...

'', ''

Brevibacillus ''Brevibacillus'' is a genus of Gram-positive bacteria in the family Paenibacillaceae The Paenibacillaceae are a family of Gram-positive In bacteriology, gram-positive bacteria are bacteria that give a positive result in the Gram stain tes ...

Solibacillus ''Solibacillus'' is a genus of Gram positive, rod shaped, spore-forming bacteria. The first member of ''Solibacillus'' was first isolated in 1999, and was originally called ''Bacillus silvestris''. However, further studies on ''B. silvestris'' ...

'', ''

Alicyclobacillus ''Alicyclobacillus'' is a genus of Gram-variable, rod-shaped, spore-forming bacteria. The bacteria are able to grow in acidic conditions, while the spores are able to survive typical pasteurization procedures. Overview ''Alicyclobacilli'' ar ...

,'' ''

Virgibacillus ''Virgibacillus'' is a genus of Gram-positive, rod-shaped (bacillus) bacteria and a member of the phylum Bacillota. ''Virgibacillus'' species can be obligate aerobes (oxygen reliant), or facultative anaerobes and catalase enzyme positive. Under s ...

'' and ''

Evansella ''Evansella'' is a genus of Gram-positive rod-shaped bacteria in the family ''Bacillaceae'' within the order ''Bacillales''. The type species for this genus is ''Evansella cellulosilytica.'' Members of ''Evansella'' was transferred from the genu ...

''. In addition, the genus ''Bacillus'' has been restricted to only include species closely related to ''

Bacillus subtilis ''Bacillus subtilis'', known also as the hay bacillus or grass bacillus, is a Gram-positive, catalase-positive bacterium, found in soil and the gastrointestinal tract of ruminants, humans and marine sponges. As a member of the genus ''Bacillu ...

'' and ''

Bacillus cereus ''Bacillus cereus'' is a Gram-positive rod-shaped bacterium commonly found in soil, food, and marine sponges. The specific name, ''cereus'', meaning "waxy" in Latin, refers to the appearance of colonies grown on blood agar. Some strains are ha ...

.'' The name ''Alkalicoccus'' is derived from the prefix "-alkali" (from the Arabic article ''al'', which translates to "the" and the Arabic noun ''galiy'', referring to the ashes of saltwort) and the suffix "-coccus" (from the Latin ''coccus'', referring to a sphere). Together, ''Alkalicoccus'' translates to a coccus living in basic surroundings.

Biochemical characteristics and molecular signatures

Members of this genus are

aerobic Aerobic means "requiring air," in which "air" usually means oxygen. Aerobic may also refer to * Aerobic exercise, prolonged exercise of moderate intensity * Aerobics, a form of aerobic exercise * Aerobic respiration, the aerobic process of cellu ...

facultatively anaerobic A facultative anaerobic organism is an organism that makes ATP by aerobic respiration if oxygen is present, but is capable of switching to fermentation if oxygen is absent. Some examples of facultatively anaerobic bacteria are ''Staphylococcus' ...

and found in mainly in saline lakes. Some members can produce endospores and are motile. Most species are moderately halophilic and alkali-tolerant and require NaCl (2–8%, w/v) for growth. Temperature range for growth is 8–45 °C, with optimum growth temperature generally in the range 30–37 °C.` Analyses of genome sequences from ''Alkalicoccus'' species identified nine

conserved signature indels Conserved signature inserts and deletions (CSIs) in protein sequences provide an important category of molecular markers for understanding phylogenetic relationships. CSIs, brought about by rare genetic changes, provide useful phylogenetic markers ...

(CSIs) that are exclusive for this genus in the following proteins: bis(5'-nucleosyl)-tetraphosphatase PrpE, dihydroorotate dehydrogenase electron transfer subunit, DUF368 domain-containing protein,

penicillin-binding protein Penicillin-binding proteins (PBPs) are a group of proteins that are characterized by their affinity for and binding of penicillin. They are a normal constituent of many bacteria; the name just reflects the way by which the protein was discov ...

, DNA polymerase/3'−5' exonuclease PolX,

alpha-glucosidase α-Glucosidase (EC 3.2.1.20, maltase, glucoinvertase, glucosidosucrase, maltase-glucoamylase, α-glucopyranosidase, glucosidoinvertase, α-D-glucosidase, α-glucoside hydrolase, α-1,4-glucosidase, α-D-glucoside glucohydrolase; systematic na ...

, 1,4-alpha-glucan branching protein GlgB, SDR family oxidoreductase and tRNA1(Val) denine(37)-N6methyltransferase. These molecular signatures provide a reliable method of identification and differentiation for ''Alkalicoccus'' species from other ''Bacillaceae'' genera and bacteria.

Taxonomy

''Alkalicoccus'', as of May 2021, contains a total of 6 species with validly published names. This genus was identified as a

monophyletic In cladistics for a group of organisms, monophyly is the condition of being a clade—that is, a group of taxa composed only of a common ancestor (or more precisely an ancestral population) and all of its lineal descendants. Monophyletic gro ...

clade and phylogenetically unrelated to other ''Bacillus'' species in studies examining the taxonomic relationships within ''Bacillus''. This branching pattern is also observed in the

Genome Taxonomy Database The Genome Taxonomy Database (GTDB) is an online database that maintains information on a proposed nomenclature of prokaryotes, following a phylogenomic approach based on a set of conserved single-copy proteins. In addition to breaking up parap ...

(GTDB). One non-validly published species, "Bacillus daqingensis", is also found to group with other members of ''Alkalicoccus'' in phylogenetic trees as well as share the same molecular markers in the form of

(CSIs). However, its transfer was not officially proposed due to the lack of culture strain information. Further revision of this genus is required as additional genomes and novel species are discovered and assigned.

References

{{Taxonbar, from=Q62611482 Bacillaceae Bacteria genera