Nomenclature Of Prokaryotes Research Articles

Opinion: Response to concerns about the use of DNA sequences as types in the nomenclature of prokaryotes

In the current Opinion we respond to the major concerns by Bisgaard et al. (2019) and Overmann et al. (2019) and conclude that the adoption of sequences as types for the names of prokaryotes will allow for improvements of the taxonomic framework, increased stability of names derived from robust phylogenomic methods, and enable a full circumscription of the microbial world rather than just the cultivated minority.

Necessity and rationale for the proposed name changes in the classification of Mollicutes species. Reply to: 'Recommended rejection of the names Malacoplasma gen. nov., Mesomycoplasma gen. nov., Metamycoplasma gen. nov., Metamycoplasmataceae fam. nov., Mycoplasmoidaceae fam. nov., Mycoplasmoidales ord. nov., Mycoplasmoides gen. nov., Mycoplasmopsis gen. nov. [Gupta, Sawnani, Adeolu, Alnajar and Oren 2018] and all proposed species comb. nov. placed therein',

This response summarizes the highly disordered state of the Mollicutes taxonomy that existed until recently, where most Mollicutes taxa lacked proper circumscriptions and their names were not in accordance with the International Code of Nomenclature of Prokaryotes and illegitimate. We also summarize the comprehensive phylogenomic and comparative genomic studies forming the basis for the proposed changes in the classification of Mollicultes species. Our responses to the concerns raised by Balish et al., show that the proposed taxonomic changes do not violate any essential point of the Code. Instead the proposed name changes rectify numerous taxonomic anomalies that have long plagued the classification of Mollicutes species, leading to a better understanding of their evolutionary relationships and bringing their nomenclature in conformity with the Code.

Standardised Suffixes in the Nomenclature of the Higher Taxa of Prokaryotes an Aid to Data Mining, Database Administration and Automatic Assignment of Names to Taxonomic Ranks

The formation and use of the scientific names of prokaryotes is governed by the International Code of Nomenclature of Prokaryotes. Originally deriving from the 1935 revision of the International Code of Botanical Nomenclature, it retains the treatment of scientific names as Latin words. Above the rank of genus the rank is generally denoted by a single, standardised suffix. This has great advantage in text mining and database infrastructure where the identification of the standardised suffix can automatically be linked to the rank at which the scientific name is being used. The only exception at present are names at the rank of class where, although a standardised suffix has been proposed (-ia) it does not allow one to unambiguously identify the rank of the scientific name, since it is also a suffix used at the rank of genus. In addition, due to the fact that the suffix at the rank of class was not regulated in earlier versions of the International Code of Nomenclature of Bacteria, there are names that do not follow the standardised suffix. Uniformity would be an advantage. The problem and a proposed solution are discussed.

Update on the classification of higher ranks in the phylum Actinobacteria.

Genome analysis is one of the main criteria for description of new taxa. Availability of genome sequences for all the actinobacteria with a valid nomenclature will, however, require another decade's works of sequencing. This paper describes the rearrangement of the higher taxonomic ranks of the members of the phylum 'Actinobacteria', using the phylogeny of 16S rRNA gene sequences and supported by the phylogeny of the available genome sequences. Based on the refined phylogeny of the 16S rRNA gene sequences, we could arrange all the members of the 425 genera of the phylum 'Actinobacteria' with validly published names currently in use into six classes, 46 orders and 79 families, including 16 new orders and 10 new families. The order Micrococcales Prévot 1940 (Approved Lists 1980) emend. Nouioui et al. 2018 is now split into 11 monophyletic orders: the emended order Micrococcales and ten proposed new orders Aquipuribacterales, Beutenbergiales, Bogoriellales, Brevibacteriales, Cellulomonadales, Demequinales, Dermabacterales, Dermatophilales, Microbacteriales and Ruaniales. Further, the class 'Actinobacteria' Stackebrandt et al. 1997 emend. Nouioui et al. 2018 was described without any nomenclature type, and therefore the name 'Actinobacteria' is deemed illegitimate. In accordance to Rule 8 of the International Code of Nomenclature of Prokaryotes, Parker et al. 2019, we proposed the name Actinomycetia which is formed by using the stem of the name Actinomycetales Buchanan 1917 (Approved Lists 1980) emend. Zhi et al. 2009, to replace the name 'Actinobacteria'. The nomenclature type of the proposed new class Actinomycetia is the order Actinomycetales Buchanan 1917 (Approved Lists 1980) emend. Zhi et al. 2009.

Rule 24b of the International Code of Nomenclature of Prokaryotes and regulating the priority of names and epithets considered to be associated with heterotypic synonyms.

Rule 24b of the International Code of Nomenclature of Prokaryotes regulates the priority of names that are considered to be heterotypic synonyms. However, the rule is imperfect because it caters only for names that compete for priority that were only included on the Approved Lists of Bacterial Names or for names that were only validly published in the International Journal of Systematic Bacteriology or the International Journal of Systematic and Evolutionary Microbiology, either in an original article or via the Validation Lists. Although this should be self-explanatory, Rule 24b does not cater for what happens when one or more names considered to be heterotypic synonyms have appeared on the Approved Lists of Bacterial Names while other names also considered to be heterotypic synonyms were validly published in the International Journal of Systematic Bacteriology or the International Journal of Systematic and Evolutionary Microbiology, either in an original article or via the Validation Lists. Formal changes to the International Code of Nomenclature of Prokaryotes are required.

The names Hungateiclostridium Zhang et al. 2018, Hungateiclostridium thermocellum (Viljoen et al. 1926) Zhang et al. 2018, Hungateiclostridium cellulolyticum (Patel et al. 1980) Zhang et al. 2018, Hungateiclostridium aldrichii (Yang et al. 1990) Zhang et al. 2018, Hungateiclostridium alkalicellulosi (Zhilina et al. 2006) Zhang et al. 2018, Hungateiclostridium clariflavum (Shiratori et al. 2009) Zhang et al. 2018, Hungateiclostridium straminisolvens (Kato

A recent publication has created the genus name HungateiclostridiumZhang et al. 2018 and the new combinations Hungateiclostridium cellulolyticum (Patel et al. 1980) Zhang et al. 2018, Hungateiclostridium aldrichii (Yang et al. 1990.) Zhang et al. 2018, Hungateiclostridium alkalicellulosi (Zhilina et al. 2006) Zhang et al. 2018, Hungateiclostridium clariflavum (Shiratori et al. 2009) Zhang et al. 2018, Hungateiclostridium straminisolvens (Kato et al. 2004) Zhang et al. 2018 and Hungateiclostridium saccincola (Koeck et al. 2016) Zhang et al. 2018 for names at the rank of species that were previously either included in the genus ClostridiumPrazmowski 1880, Acetivibrio Patel et al. 1980 or HerbivoraxKoeck et al. 2016. Rules 23a, 38, 39b, 41a, 42 and 44 have not been followed and an illegitimate name at the rank of genus or illegitimate combinations at the rank of species as defined in Rule 51b(1) and (2) have been created. Another aspect is recognising the fact that an instance of heterotypic synonym has been created between Acetivibrio Patel et al. 1980, HerbivoraxKoeck et al. 2016 and HungateiclostridiumZhang et al. 2018, where the earliest validly published genus name is Acetivibrio Patel et al. 1980, of which the nomenclatural type is Acetivibrio cellulolyticus Patel et al. 1980. It follows from Rules 23a, 38, 39a, 39b, 41a, 42 and 44 that the genus name to be used is Acetivibrio Patel et al. 1980, with new combinations in that genus replacing those published in the genus HungateiclostridiumZhang et al. 2018, which together with the genus name are illegitimate according to Rule 51b of the International Code of Nomenclature of Prokaryotes. Additional issues are also addressed with regards to the names Pseudoclostridium thermosuccinogenes (Drent et al. 1995) Zhang et al. 2018, PseudoclostridiumZhang et al. 2018 OscillospiraceaePeshkoff 1940 (Approved Lists 1980), RuminococcaceaeRainey 2010, Eubacteriales Buchanan 1917 (Approved Lists 1980) and ClostridialesPrévot 1953 (Approved Lists 1980).

Clarification of access regulations to genetic resources that are subject to the sovereign rights of sovereign states and the deposit of nomenclatural types under the International Code of Nomenclature of Prokaryotes.

One of the goals of the International Code of Nomenclature of Prokaryotes is not only to make nomenclature transparent and predictable, but to also make sure that the biological material on which it is based is available to either verify previous work or to allow further work to be undertaken. The key elements in ensuring the latter two aspects are nomenclatural types (type strains) at the rank of species and subspecies. With increasing regulations controlling access to genetic resources, the limitations put on access are not always evident at the time novel species or subspecies are proposed and corresponding nomenclatural types (type strains) designated. In a number of cases, limitations put on access have been discovered after the fact.

The name Bradyrhizobiaceae Garrity et al. 2006 contains Nitrobacter Winogradsky 1892 (Approved Lists 1980), the nomenclatural type of the family Nitrobacteraceae Buchanan 1917 (Approved Lists 1980), is illegitimate and proposals to alter the wording of Rule 54 of the International Code of Nomenclature of Prokaryotes to clarify the fact that the family name Bradyrhizobiaceae Garrity et al. 2006 is replaced

The new name at the rank of family Bradyrhizobiaceae Garrity et al. 2006 was created to include the genera Afipia Brenner et al. 1992, Agromonas Ohta and Hattori 1985, Blastobacter Zavarzin 1961 (Approved Lists 1980), Bosea Das et al. 1996, Bradyrhizobium Jordan 1982 (the nomenclatural type), Nitrobacter Winogradsky 1892 (Approved Lists 1980), Oligotropha Meyer et al. 1994, Rhodoblastus Imhoff 2001 and Rhodopseudomonas Czurda and Maresch 1937 (Approved Lists 1980). However, Nitrobacter Winogradsky 1892 (Approved Lists 1980) is the nomenclatural type of Nitrobacteraceae Buchanan 1917 (Approved Lists 1980) a name at the rank of family that was validly published prior to the valid publication of Bradyrhizobiaceae Garrity et al. 2006 and has priority. In addition Rule 51b (1) of the International Code of Nomenclature of Prokaryotes rules that under these circumstances Bradyrhizobiaceae Garrity et al. 2006 is an illegitimate name. Illegitimate names may not be used (Rule 51a) and illegitimate names are also not taken into consideration when determining priority (Rule 23a). Nitrobacteraceae Buchanan 1917 (Approved Lists 1980) is the only correct name (Rule 23a). Despite these facts the name Bradyrhizobiaceae Garrity et al. 2006 continues to be used, perhaps because the fact that it is an illegitimate name and the consequences of that status are not fully understood. A revision of Rule 54 would also appear to be appropriate in order to further emphasise the fact that the family name Bradyrhizobiaceae Garrity et al. 2006 must be replaced by the family name Nitrobacteraceae Buchanan 1917 (Approved Lists 1980), which is the oldest legitimate name and is the only correct name that may be used for the taxon that includes Bradyrhizobium Jordan 1982 and Nitrobacter Winogradsky 1892 (Approved Lists 1980).

Genome-based taxonomic revision detects a number of synonymous taxa in the genus Mycobacterium

The aim of this study was to clarify the taxonomic status of named species within the genus Mycobacterium. The analysis of genomes belonging to 174 taxa (species or subspecies) of the genus Mycobacterium was conducted using both the Average Nucleotide Identity and the Genome to Genome Distance. A number of synonymous taxa were detected. The list of synonyms includes: two subspecies of M. chelonae (M. chelonae subsp. bovis and M. chelonae subsp. gwanakae), two subspecies of M. fortuitum (M. fortuitum subsp. fortuitum and M. fortuitum subsp. acetamidolyticum), four subspecies of M. avium (M. avium subsp. avium, M. avium subsp. silvaticum, M. avium subsp. paratuberculosis and “M. avium subsp. hominissuis”), two couples of subspecies of M. intracellulare (M. intracellulare subsp. intracellulare/M. intracellulare subsp. paraintracellulare and M. intracellulare subsp. chimaera/M. intracellulare subsp. yongonense), the species M. austroafricanum and M. vanbaalenii, the species M. senegalense and M. conceptionense, the species M. talmoniae and M. eburneum and the species M. marinum, M. ulcerans and M. pseudoshottsii. Furthermore one species were reclassified as subspecies of another mycobacterium: M. lepraemurium was reclassified as a subspecies of M. avium (M. avium subsp. lepraemurium). The updates to nomenclature are proposed basing on the priority of names according the Code of nomenclature of prokaryotes. For two species (M. bouchedurhonense and M. marseillense) the loss of standing in nomenclature is proposed because of unavailability of respective type strains in culture collections.

Marinobacterium iners (Iizuka and Komagata 1964) comb. nov. arising from the Synonymy of Marinobacterium georgiense González et al. 1997 and Pseudomonas iners Iizuka and Komagata 1964 (Approved Lists 1980).

Although there is documented evidence in the literature that Marinobacterium georgiense González et al. 1997 and Pseudomonas iners Iizuka and Komagata 1964 (Approved Lists 1980) should be treated as heterotypic synonyms, the nomenclatural consequences have not been implemented. Based on the rules of the International Code of Nomenclature of Prokaryotes when Marinobacterium georgiense González et al. 1997 and Pseudomonas iners Iizuka and Komagata 1964 (Approved Lists 1980) are considered to belong to the genus Marinobacterium González et al. 1997, the earliest epithet (from the competing heterotypic synonyms) is to be used for the resulting taxon, i.e., the combination Marinobacterium iners (Iizuka and Komagata 1964) must be created.

The role of incorrect citation of the International Code of Nomenclature of Prokaryotes and subsequent misinterpretation in causing unnecessary nomenclatural confusion.

The list that notifies names published in volume 68, part 1 of the International Journal of Systematic and Evolutionary Microbiology provides the information that a number of names of species in the genus Clavibacter that had previously been treated as names at the rank of subspecies were illegitimate because they contravene Rule 34a and Rule 50a of the International Code of Nomenclature of Prokaryotes. Rule 34a deals with combinations at the same rank and this rule does not apply to names that involve a change in rank. Rule 34a, b and c all fall under the heading new combinations and that in the case of names at the rank of species and subspecies where a change in rank is made Rule 34c applies. Rule 50a applies to names at the rank of subspecies that are elevated to species, but it is unclear why these nomenclatural changes lead to illegitimate names. Fortunately the Code is explicit in stating the role of the Notification Lists is limited to allowing orthographic corrections to be made. It is necessary to publish an interpretation of the status of these names that is consistent with the current wording of the Code.

The status of names whose nomenclatural types are based on strains deposited solely for patent purposes.

The International Code of Nomenclature of Prokaryotes specifically forbids the use of strains deposited solely for patent purposes from serving as nomenclatural types. Despite this ruling there are a number of names at the rank of species where strains deposited solely for patent purposes have been designated as the nomenclatural type. In some cases there is only a single deposit where the strain is deposited solely for patent purposes or there are two or more deposits in culture collections, one (or more) of which is a strain deposited solely for patent purposes. In such instances the requirements of Rule 30 may not be fulfilled and the valid publication of the corresponding names called into question because nomenclatural types have not been deposited in at least two publicly accessible culture collections in different countries.

On the status of the names Corynebacteriales Goodfellow and Jones 2015, Mycobacteriales Janke 1924 (Approved Lists 1980) and Mycobacteriales Cavalier-Smith 2002.

The name CorynebacterialesGoodfellow and Jones 2015 has been validly published by inclusion in Validation List 164, with the nomenclatural type defined as CorynebacteriumLehmann and Neumann 1896 (Approved Lists 1980). The name MycobacterialesJanke 1924 (Approved Lists 1980) appeared on the Approved Lists of Bacterial Names and is validly published, with the nomenclatural type defined as MycobacteriumLehmann and Neumann 1896 (Approved Lists 1980). The name Mycobacteriales Cavalier-Smith 2002 was validly published by inclusion in an article in the International Journal of Systematic and Evolutionary Microbiology with the nomenclatural type defined as MycobacteriumLehmann and Neumann 1896 (Approved Lists 1980). As circumscribed by the authors MycobacterialesJanke 1924 (Approved Lists 1980), Mycobacteriales Cavalier-Smith 2002 and CorynebacterialesGoodfellow and Jones 2015 all contain the genus MycobacteriumLehmann and Neumann 1896 (Approved Lists 1980), which is the nomenclatural type of MycobacterialesJanke 1924 (Approved Lists 1980). Consequently, the name CorynebacterialesGoodfellow and Jones 2015 is not the earliest validly published name, contravenes Rule 51b (1) of the International Code of Nomenclature of Prokaryotes and according to Rule 54 must be replaced. In the case of Mycobacteriales Cavalier-Smith 2002 the status of the name appears to be currently uncertain, but a solution may be in sight.

Minimal standards for the description of new genera and species of rhizobia and agrobacteria

Herein the members of the Subcommittee on Taxonomy of Rhizobia and Agrobacteria of the International Committee on Systematics of Prokaryotes review recent developments in rhizobial and agrobacterial taxonomy and propose updated minimal standards for the description of new species (and genera) in these groups. The essential requirements (minimal standards) for description of a new species are (1) a genome sequence of at least the proposed type strain and (2) evidence for differentiation from other species based on genome sequence comparisons. It is also recommended that (3) genetic variation within the species is documented with sequence data from several clearly different strains and (4) phenotypic features are described, and their variation documented with data from a relevant set of representative strains. Furthermore, it is encouraged that information is provided on (5) nodulation or pathogenicity phenotypes, as appropriate, with relevant gene sequences. These guidelines supplement the current rules of general bacterial taxonomy, which require (6) a name that conforms to the International Code of Nomenclature of Prokaryotes, (7) validation of the name by publication either directly in the International Journal of Systematic and Evolutionary Microbiology or in a validation list when published elsewhere, and (8) deposition of the type strain in two international culture collections in separate countries.

Proposal for changes in the International Code of Nomenclature of Prokaryotes: granting priority to Candidatus names.

Currently, the description of taxa designated Candidatus requires gene sequences and other taxonomically relevant available information in the absence of an isolated pure culture, and Candidatus names are provisional, i.e. without formal standing in nomenclature. If gene sequences are accepted as suitable type material for the description of prokaryotic species, many taxa designated Candidatus would fulfil all the requirements in the International Code of Nomenclature of Prokaryotes for priority. Here we propose that upon acceptance of sequence data as type material, all Candidatus names published before 1 January 2020 which are otherwise in accordance with the rules of the Code will have their priority based upon their date of publication in the International Journal of Systematic and Evolutionary Microbiology, either within a paper, a list of names of Candidatus taxa, or a Validation List, unless a synonymous name already exists based upon deposition of type cultures. We further propose that modifications of the superscript 'T' be used to identify the nomenclatural types. If the type material is a culture, the superscript 'T' will continue to be used. If the type material is a sequence, the superscript 'Ts' will be used. If the type material is some other form of description, the superscript 'Td' will be used.

The use of Greek and Latin prepositions and prefixes in compound names: proposed emendation of Appendix 9 of the International Code of Nomenclature of Prokaryotes.

Part A of Appendix 9 - Orthography of the International Code of Nomenclature of Prokaryotes regulates the formation of compound generic names and specific epithets derived by combining two or more words or word elements of Latin and/or Greek origin, using the word stems and connecting vowels (-o- or -i-) following word elements derived from Greek and Latin, respectively. The rules given and the exceptions listed are suitable for substantives (nouns) and adjectives used as word elements, but not for prepositions and prefixes. Therefore, we propose a non-retroactive modification of Appendix 9 so that the guidelines given in Part A apply only to compound names that include a noun or an adjective in a non-final position. We also propose guidelines for the proper use of Greek and Latin prepositions, prefixes and adverbs in compound names in which the following word element starts with a vowel.

When treated as heterotypic synonyms the names Caryophanaceae Peshkoff 1939 (Approved Lists 1980) and Caryophanales Peshkoff 1939 (Approved Lists 1980) have priority over the names Planococcaceae Krasil'nikov 1949 (Approved Lists 1980) and Bacillales Prévot 1953 (Approved Lists 1980), respectively.

The International Code of Nomenclature of Prokaryotes provides rules that govern the way names are to be selected based on priority of valid publication when two or more alternatives (synonyms) are available. However, these rules are not always followed. In the case of the name CaryophanaceaePeshkoff 1939 (Approved Lists 1980), when its nomenclatural type CaryophanonPeshkoff 1939 (Approved Lists 1980) is placed in the same taxon as PlanococcusMigula 1894 (Approved Lists 1980), the nomenclatural type of PlanococcaceaeKrasil'nikov 1949 (Approved Lists 1980), then the two are considered to be heterotypic synonyms and the name which has priority is CaryophanaceaePeshkoff 1939 (Approved Lists 1980). Similarly in the case of the name CaryophanalesPeshkoff 1939 (Approved Lists 1980) when its nomenclatural type CaryophanonPeshkoff 1939 (Approved Lists 1980) is placed in the same taxon as Bacillus Cohn 1872 (Approved Lists 1980), the nomenclatural type of BacillalesPrévot 1953 (Approved Lists 1980), then the two are considered to be heterotypic synonyms and the name which has priority is CaryophanalesPeshkoff 1939 (Approved Lists 1980) While the rules of the International Code of Nomenclature of Prokaryotes are unambiguous in determining the correct names despite the fact that the names CaryophanaceaePeshkoff 1939 (Approved Lists 1980) and CaryophanalesPeshkoff 1939 (Approved Lists 1980) are rarely used.

Clarifying the definition and role of effective publication in the International Code of Nomenclature of Prokaryotes with proposals to make changes.

The term effective publication and the adjectival form effectively published occur at numerous points in the International Code of Nomenclature of Prokaryotes. As defined in Rule 25a the term refers to a form of publication rather than to names or descriptions. Although names are also defined as being effectively published, which is also defined as a status under the International Code of Nomenclature of Prokaryotes, such names are not automatically validly published and only validly published names can have a status under the Code. If one clearly separates the act of publication of scientific works from other elements of the Code then it is possible to clarify the workings of the Code whereby only names included in scientific works that are published in accordance with Rule 25a may have a status under the Code once they are validly published. Similarly names would then be validly published or not validly published, with the latter, irrespective of where they are found, having no status under the International Code of Nomenclature of Prokaryotes.

Proposal to modify the Rules of the International Code of Nomenclature of Prokaryotes to abolish the taxonomic categories Subfamily, Subtribe and Kingdom.

Although the taxonomic categories covered by the International Code of Nomenclature of Prokaryotes include the ranks of Subtribe (Subtribus) and Subfamily (Subfamilia), no names of taxa belonging to these ranks have been validly published. To simplify the Rules of the Code I propose abolishing these ranks. The rank of Kingdom is mentioned once in the Code, in an example to Rule 8, but it is not further defined. Therefore, I propose modifying that example so that the rank of Kingdom is no longer mentioned in the Code.

Naming classes of prokaryotes based on the rules of Latin grammar

Recently a proposal was published to unify Rules 7, 8 and 9 of the International Code of Nomenclature of Prokaryotes. Based on this proposal, all names of taxa above the rank of genus must be in the feminine gender, the plural number. For the rank of class, this proposal contravenes Principle 3 of the Code, which states that the scientific names of all taxa are treated as Latin. The -ia ending of most names of classes belongs to nominative plural nouns of the neuter gender.