Litchfieldia Explained

Litchfieldia is a genus of Gram-positive rod-shaped bacteria in the family Bacillaceae within the order Bacillales.^{[1] [2]} The type species for this genus is Litchfieldia alkalitelluris.^[3]

Litchfieldia is composed of species originally belonging to the genus Bacillus, a genus that displayed extensive polyphyly due to the vague criteria used to assign new species to the genus.^{[4] [5] [6]} Studies using phylogenetic and comparative genomic analyses have clarified the taxonomy of Bacillus by restricting the genus to only include species closely related to Bacillus subtilis and Bacillus cereus^[7] as well as transfer many species into new novel genera such as Virgibacillus, Solibacillus, Brevibacillus and Ectobacillus.^{[8] [9] [10]}

The name Litchfieldia was named after the American marine microbiologist and ecologist Dr. Carol D. Litchfield (1936-2012).

Biochemical characteristics and molecular signatures

Members of the genus Litchfieldia are aerobic or facultatively anaerobic bacteria. They are all endospore-forming and motile cells. They are catalase-positive, oxidase-positive and slightly halophilic. They can grow in environments containing 0-4% (w/v) sodium chloride (NaCl), but grow best in 0-3% (w/v) NaCl. Grow also occurs at NaNabbr=NaNabbr= (optimally at NaNabbr=NaNabbr=) and pH 7.0–10.0 (optimally at pH 8.0–9.0).

Analyses of genome sequences from Litchfieldia species identified seven conserved signature indels that are unique for the genus Litchifieldia in the following proteins: MFS transporter, M15 family metallopeptidase, amidohydrolase, response regulator transcription factor, hypothetical proteins, and l-glutamate gamma-semialdehyde dehydrogenase. These molecular signatures provide a reliable way to distinguish members of this genus from other Bacillaceae genera and bacteria.

Taxonomy

, there are a total of 2 species with validly published names in the genus Litchfieldia. Members of this genus group together to form a monophyletic branch in various phylogenetic trees constructed based on concatenated sequences from various protein datasets, as well as 16S ribosomal RNA sequences. This branching pattern was also reflected in the Genome Taxonomy Database.^[11]

There is one non-validly published species, Bacillus cheonanensis, that was also found to branch reliably with other members of the Litchfieldia clade as well as share the unique molecular markers. However, transfer was not proposed for this species due to the lack of culture strain information. Future analyses of this clade should be conducted when additional genome sequence and culture strain information becomes available.

Notes and References

1. Gupta. Radhey S.. Patel. Sudip. Saini. Navneet. Chen. Shu. 2020-11-01. Robust demarcation of 17 distinct Bacillus species clades, proposed as novel Bacillaceae genera, by phylogenomics and comparative genomic analyses: description of Robertmurraya kyonggiensis sp. nov. and proposal for an emended genus Bacillus limiting it only to the members of the Subtilis and Cereus clades of species. International Journal of Systematic and Evolutionary Microbiology. en. 70. 11. 5753–5798. 10.1099/ijsem.0.004475. 1466-5026. 33112222. free.
2. Book: 2005. Brenner. Don J.. Krieg. Noel R.. Staley. James T.. Garrity. George M.. Boone. David R.. De Vos. Paul. Goodfellow. Michael. Rainey. Fred A.. Schleifer. Karl-Heinz. Bergey's Manual® of Systematic Bacteriology. 10.1007/0-387-28022-7. 978-0-387-24144-9.
3. Web site: Genus: Litchfieldia. 2021-05-29. lpsn.dsmz.de. en.
4. Logan. N.A.. 2011-12-20. Bacillus and relatives in foodborne illness. Journal of Applied Microbiology. 112. 3. 417–429. 10.1111/j.1365-2672.2011.05204.x. 1364-5072. 22121830. free.
5. La Duc. Myron T. Satomi. Masataka. Agata. Norio. Venkateswaran. Kasthuri. March 2004. gyrB as a phylogenetic discriminator for members of the Bacillus anthracis–cereus–thuringiensis group. Journal of Microbiological Methods. 56. 3. 383–394. 10.1016/j.mimet.2003.11.004. 0167-7012. 14967230.
6. Ash. Carol. Farrow. J.A.E.. Wallbanks. Sally. Collins. M.D.. 2008-06-28. Phylogenetic heterogeneity of the genus Bacillus revealed by comparative analysis of small-subunit-ribosomal RNA sequences. Letters in Applied Microbiology. 13. 4. 202–206. 10.1111/j.1472-765x.1991.tb00608.x. 82988953. 0266-8254.
7. Patel. Sudip. Gupta. Radhey S.. 2020-01-01. A phylogenomic and comparative genomic framework for resolving the polyphyly of the genus Bacillus: Proposal for six new genera of Bacillus species, Peribacillus gen. nov., Cytobacillus gen. nov., Mesobacillus gen. nov., Neobacillus gen. nov., Metabacillus gen. nov. and Alkalihalobacillus gen. nov.. International Journal of Systematic and Evolutionary Microbiology. en. 70. 1. 406–438. 10.1099/ijsem.0.003775. 1466-5026. 31617837. free.
8. Heyndrickx. M.. Lebbe. L.. Kersters. K.. Hoste. B.. De Wachter. R.. De Vos. P.. Forsyth. G.. Logan. N. A.. 1999-07-01. Proposal of Virgibacillus proomii sp. nov. and emended description of Virgibacillus pantothenticus (Proom and Knight 1950) Heyndrickx et al. 1998. International Journal of Systematic and Evolutionary Microbiology. 49. 3. 1083–1090. 10.1099/00207713-49-3-1083. 1466-5026. 10425765. free.
9. Shida. O.. Takagi. H.. Kadowaki. K.. Komagata. K.. 1996-10-01. Proposal for Two New Genera, Brevibacillus gen. nov. and Aneurinibacillus gen. nov.. International Journal of Systematic Bacteriology. en. 46. 4. 939–946. 10.1099/00207713-46-4-939. 0020-7713. 8863420. free.
10. Mual. Poonam. Singh. Nitin Kumar. Verma. Ashish. Schumann. Peter. Krishnamurthi. Srinivasan. Dastager. Syed. Mayilraj. Shanmugam. 2016-05-01. Reclassification of Bacillus isronensis Shivaji et al. 2009 as Solibacillus isronensis comb. nov. and emended description of genus Solibacillus Krishnamurthi et al. 2009. International Journal of Systematic and Evolutionary Microbiology. en. 66. 5. 2113–2120. 10.1099/ijsem.0.000982. 1466-5026. 26907585. free.
11. Web site: GTDB - Tree. 2021-05-25. gtdb.ecogenomic.org.