| Neobacillus | |
|---|---|
Scientific classification | |
| Domain: | Bacteria |
| Kingdom: | Bacillati |
| Phylum: | Bacillota |
| Class: | Bacilli |
| Order: | Bacillales |
| Family: | Bacillaceae |
| Genus: | Neobacillus Patel and Gupta 2020 |
| Species | |
Neobacillus is a genus of rod-shaped bacteria that showGram-positive or Gram-variable staining.[1] This genus belongs under the familyBacillaceae within the orderBacillales.[2] The type species ofNeobacillus isNeobacillus niacini.[3]
Members of this genus were previously part of the genusBacillus. It has long been recognized that the genusBacillus comprises a wide range of phylogenetically unrelated bacteria, demonstrated through multiple phylogenetic studies and comparative genome studies.[4][5]Bacillus species were assigned based on vague criteria such as the ability to form endospores in the presence of oxygen, a criterion that many diverse, unrelated bacteria share.[6][7] The result is a big genus comprising over 300 species with distinct biochemical characteristics that are not uniquely shared by all members, leaving no way to reliably distinguishBacillus species from other bacteria. Subsequently, many studies have used phylogenetic analyses as a means to clarify the evolutionary relationships betweenBacillus species, resulting in the establishment of many novel genera such asVirgibacillus,Solibacillus,Brevibacillus, andEctobacillus.[8][9][10][11] Additionally,Bacillus has been restricted to included only species closely related toBacillus subtilis andBacillus cereus.[1][11]
The nameNeobacillus is pieced together using the prefix "neo-" (from the Greek adjectiveneos, translating to new) and the suffix "-bacillus" (from the Latin nounbacillus, referring to a small staff or rod andBacillus, the bacterial genus). Together, the name translates to "newBacillus".[1]
Members ofNeobacillus can be eitheraerobic orfacultatively anaerobic.Motility is variable, some species are motile while others are non-motile. All studied species are observed to formendospores under adverse environmental or nutritional conditions.Neobacillus can be found in a variety of environments, including soil, human origin (gut and skin) and plant roots.Neobacillus can grow in temperatures up to 50-55°C, but optimal growth occurs in the range of 25-37°C.
11conserved signature indels (CSIs) have been identified through genomic analysis as exclusive forNeobacillus in proteins such as 50S ribosomal protein L24, flagellar M-ring protein FliF, 50S ribosomal protein L11 methyltransferase, imidazole glycerol phosphate synthase subunit HisH, ATP phosphoribosyltransferase regulatory subunit, LTA synthase family protein,type I DNA topoisomerase,nicotinate phosphoribosyltransferase, bifunctional hydroxymethylpyrimidine kinase/phospho- methylpyrimidine kinase, single-stranded-DNA-specific exonuclease RecJ and1-deoxy-d-xylulose-5-phosphate synthase.[1] These CSIs provide reliable methods to differentiateNeobacillus from otherBacillaceae genera and bacteria in molecular terms.
As of May 2021, there are a total of 17 species with validly published names in the genusNeobacillus.[3] Members of this genus group together and forms amonophyletic branch in phylogenetic trees created from concatenated sequences from various datasets of conserved proteins as well as16S rRNA gene sequences.[1] TheGenome Taxonomy Database (GTDB) also shows members ofNeobacillus grouping together.[12]
Additional phylogenetic studies have identified a number of non-validly published species ("Bacillus ferrooxidans", "Bacillus rubiinfantis","Bacillus marasmi" and "Bacillus salipaludis") that are considered to be members of this genus based on taxonomic placement in phylogenetic trees as well as shared molecular markers (specificallyconserved signature indels) with other members ofNeobacillus.[11][13] However, transfer was not proposed due to the lack of strain culture information. As additional culture information and genome sequences become available in the future, it would be necessary to revisit the taxonomic classifications proposed for this genus to update and validate the results, as done in 2022 forBacillus dielmonensis.[13]