Why and how to use the SeqCode.

The SeqCode, formally called the Code of Nomenclature of Prokaryotes Described from Sequence Data, is a new code of nomenclature in which genome sequences are the nomenclatural types for the names of prokaryotic species. While similar to the International Code of Nomenclature of Prokaryotes (ICNP) in structure and rules of priority, it does not require the deposition of type strains in international culture collections. Thus, it allows for the formation of permanent names for uncultured prokaryotes whose nearly complete genome sequences have been obtained directly from environmental DNA as well as other prokaryotes that cannot be deposited in culture collections. Because the diversity of uncultured prokaryotes greatly exceeds that of readily culturable prokaryotes, the SeqCode is the only code suitable for naming the majority of prokaryotic species. The start date of the SeqCode was January 1, 2022, and the online Registry (https://seqco.de/) was created to ensure valid publication of names. The SeqCode recognizes all names validly published under the ICNP before 2022. After that date, names validly published under the SeqCode compete with ICNP names for priority. As a result, species can have only one name, either from the SeqCode or ICNP, enabling effective communication and the creation of unified taxonomies of uncultured and cultured prokaryotes. The SeqCode is administered by the SeqCode Committee, which is comprised of the SeqCode Community and elected administrative components. Anyone with an interest in the systematics of prokaryotes is encouraged to join the SeqCode Community and participate in the development of this resource.

Judicial Opinion 130.

Opinion 130 deals with a Request for an Opinion asking the Judicial Commission to clarify whether the genus name Rhodococcus Zopf 1891 (Approved Lists 1980) is illegitimate. The Request is approved and an answer is given. The name Rhodococcus Zopf 1891 (Approved Lists 1980) is illegitimate because it is a later homonym of the validly published cyanobacterial name Rhodococcus Hansgirg 1884. The Judicial Commission also clarifies that it has the means to resolve such cases by conserving a name over an earlier homonym. It is concluded that the name Rhodococcus Zopf 1891 (Approved Lists 1980) is significantly more important than the name Rhodococcus Hansgirg 1884 and therefore the former is conserved over the latter. This makes the name Rhodococcus Zopf 1891 (Approved Lists 1980) legitimate.

Putative genome contamination has minimal impact on the GTDB taxonomy.

The Genome Taxonomy Database (GTDB) provides a species to domain classification of publicly available genomes based on average nucleotide identity (ANI) (for species) and a concatenated gene phylogeny normalized by evolutionary rates (for genus to phylum), which has been widely adopted by the scientific community. Here, we use the Genome UNClutterer (GUNC) software to identify putatively contaminated genomes in GTDB release 07-RS207. We found that GUNC reported 35,723 genomes as putatively contaminated, comprising 11.25 % of the 317,542 genomes in GTDB release 07-RS207. To assess the impact of this high level of inferred contamination on the delineation of taxa, we created 'clean' versions of the 34,846 putatively contaminated bacterial genomes by removing the most contaminated half. For each clean half, we re-calculated the ANI and concatenated gene phylogeny and found that only 77 (0.22 %) of the genomes were not consistent with their original classification. We conclude that the delineation of taxa in GTDB is robust to the putative contamination detected by GUNC.

Novel spore-forming species exhibiting intrinsic resistance to third- and fourth-generation cephalosporins and description of Tigheibacillus jepli gen. nov., sp. nov.

A comprehensive microbial surveillance was conducted at NASA's Mars 2020 spacecraft assembly facility (SAF), where whole-genome sequencing (WGS) of 110 bacterial strains was performed. One isolate, designated 179-BFC-A-HST, exhibited less than 80% average nucleotide identity (ANI) to known species, suggesting a novel organism. This strain demonstrated high-level resistance [minimum inhibitory concentration (MIC) >256 mg/L] to third-generation cephalosporins, including ceftazidime, cefpodoxime, combination ceftazidime/avibactam, and the fourth-generation cephalosporin cefepime. The results of a comparative genomic analysis revealed that 179-BFC-A-HST is most closely related to Virgibacillus halophilus 5B73CT, sharing an ANI of 78.7% and a digital DNA-DNA hybridization (dDDH) value of 23.5%, while their 16S rRNA gene sequences shared 97.7% nucleotide identity. Based on these results and the recent recognition that the genus Virgibacillus is polyphyletic, strain 179-BFC-A-HST is proposed as a novel species of a novel genus, Tigheibacillus jepli gen. nov., sp. nov (type strain 179-BFC-A-HST = DSM 115946T = NRRL B-65666T), and its closest neighbor, V. halophilus, is proposed to be reassigned to this genus as Tigheibacillus halophilus comb. nov. (type strain 5B73CT = DSM 21623T = JCM 21758T = KCTC 13935T). It was also necessary to reclassify its second closest neighbor Virgibacillus soli, as a member of a novel genus Paracerasibacillus, reflecting its phylogenetic position relative to the genus Cerasibacillus, for which we propose Paracerasibacillus soli comb. nov. (type strain CC-YMP-6T = DSM 22952T = CCM 7714T). Within Amphibacillaceae (n = 64), P. soli exhibited 11 antibiotic resistance genes (ARG), while T. jepli encoded for 3, lacking any known ß-lactamases, suggesting resistance from variant penicillin-binding proteins, disrupting cephalosporin efficacy. P. soli was highly resistant to azithromycin (MIC >64 mg/L) yet susceptible to cephalosporins and penicillins. IMPORTANCE: The significance of this research extends to understanding microbial survival and adaptation in oligotrophic environments, such as those found in SAF. Whole-genome sequencing of several strains isolated from Mars 2020 mission assembly cleanroom facilities, including the discovery of the novel species Tigheibacillus jepli, highlights the resilience and antimicrobial resistance (AMR) in clinically relevant antibiotic classes of microbes in nutrient-scarce settings. The study also redefines the taxonomic classifications within the Amphibacillaceae family, aligning genetic identities with phylogenetic data. Investigating ARG and virulence factors (VF) across these strains illuminates the microbial capability for resistance under resource-limited conditions while emphasizing the role of human-associated VF in microbial survival, informing sterilization practices and microbial management in similar oligotrophic settings beyond spacecraft assembly cleanrooms such as pharmaceutical and medical industry cleanrooms.

Judicial Opinion 129.

Opinion 129 addresses the status of Firmicutes corrig. Gibbons and Murray 1978 (Approved Lists 1980). The name has the category 'division' and was included in the Approved Lists of Bacterial Names, although that category had previously been removed from the International Code of Nomenclature of Bacteria (1975 revision onwards). When the category 'phylum' was introduced into the International Code of Nomenclature of Prokaryotes (ICNP) in 2021, equivalence between 'phylum' and 'division' was not stipulated. Since the definition of the taxonomic categories and their relative order is one of the principal tasks of every code of nomenclature, the inclusion of Firmicutes corrig. Gibbons and Murray 1978 in the Approved Lists was an error. The name is either not validly published or illegitimate because its category is not covered by the ICNP. If Firmicutes corrig. Gibbons and Murray 1978 (Approved Lists 1980) was a validly published phylum name, it would be illegitimate because it would contravene Rule 8, which does not permit any deviation from the requirement to derive a phylum name from the name of the type genus. Since Firmicutes corrig. Gibbons and Murray 1978 is also part of a 'misfitting megaclassification' recognized in Opinion 128, the name is rejected, without any pre-emption regarding a hypothetically validly published name Firmicutes at the rank of phylum. Gracilicutes Gibbons and Murray 1978 (Approved Lists 1980) and Anoxyphotobacteriae Gibbons and Murray 1978 (Approved Lists 1980) are also rejected. The validly published phylum names have a variety of advantages over their not validly published counterparts and cannot be replaced with ad hoc names suggested in the literature. To ease the transition, it is recommended to mention the not validly published phylum names which strongly deviate in spelling from their validly published counterparts along with the latter in publications during the next years.

Andean soil-derived lignocellulolytic bacterial consortium as a source of novel taxa and putative plastic-active enzymes.

An easy and straightforward way to engineer microbial environmental communities is by setting up liquid enrichment cultures containing a specific substrate as the sole source of carbon. Here, we analyzed twenty single-contig high-quality metagenome-assembled genomes (MAGs) retrieved from a microbial consortium (T6) that was selected by the dilution-to-stimulation approach using Andean soil as inoculum and lignocellulose as a selection pressure. Based on genomic metrics (e.g., average nucleotide and amino acid identities) and phylogenomic analyses, 15 out of 20 MAGs were found to represent novel bacterial species, with one of those (MAG_26) belonging to a novel genus closely related to Caenibius spp. (Sphingomonadaceae). Following the rules and requirements of the SeqCode, we propose the name Andeanibacterium colombiense gen. nov., sp. nov. for this taxon. A subsequent functional annotation of all MAGs revealed that MAG_7 (Pseudobacter hemicellulosilyticus sp. nov.) contains 20, 19 and 16 predicted genes from carbohydrate-active enzymes families GH43, GH2 and GH92, respectively. Its lignocellulolytic gene profile resembles that of MAG_2 (the most abundant member) and MAG_3858, both of which belong to the Sphingobacteriaceae family. Using a database that contains experimentally verified plastic-active enzymes (PAZymes), twenty-seven putative bacterial polyethylene terephthalate (PET)-active enzymes (i.e., alpha/beta-fold hydrolases) were detected in all MAGs. A maximum of five putative PETases were found in MAG_3858, and two PETases were found to be encoded by A. colombiense. In conclusion, we demonstrate that lignocellulose-enriched liquid cultures coupled with genome-resolved metagenomics are suitable approaches to unveil the hidden bacterial diversity and its polymer-degrading potential in Andean soil ecosystems.

A long-awaited taxogenomic investigation of the family Halomonadaceae.

The family Halomonadaceae is the largest family composed of halophilic bacteria, with more than 160 species with validly published names as of July 2023. Several classifications to circumscribe this family are available in major resources, such as those provided by the List of Prokaryotic names with Standing in Nomenclature (LPSN), NCBI Taxonomy, Genome Taxonomy Database (GTDB), and Bergey's Manual of Systematics of Archaea and Bacteria (BMSAB), with some degree of disagreement between them. Moreover, regardless of the classification adopted, the genus Halomonas is not phylogenetically consistent, likely because it has been used as a catch-all for newly described species within the family Halomonadaceae that could not be clearly accommodated in other Halomonadaceae genera. In the past decade, some taxonomic rearrangements have been conducted on the Halomonadaceae based on ribosomal and alternative single-copy housekeeping gene sequence analysis. High-throughput technologies have enabled access to the genome sequences of many type strains belonging to the family Halomonadaceae; however, genome-based studies specifically addressing its taxonomic status have not been performed to date. In this study, we accomplished the genome sequencing of 17 missing type strains of Halomonadaceae species that, together with other publicly available genome sequences, allowed us to re-evaluate the genetic relationship, phylogeny, and taxonomy of the species and genera within this family. The approach followed included the estimate of the Overall Genome Relatedness Indexes (OGRIs) such as the average amino acid identity (AAI), phylogenomic reconstructions using amino acid substitution matrices customized for the family Halomonadaceae, and the analysis of clade-specific signature genes. Based on our results, we conclude that the genus Halovibrio is obviously out of place within the family Halomonadaceae, and, on the other hand, we propose a division of the genus Halomonas into seven separate genera and the transfer of seven species from Halomonas to the genus Modicisalibacter, together with the emendation of the latter. Additionally, data from this study demonstrate the existence of various synonym species names in this family.

Proposal of names for 329 higher rank taxa defined in the Genome Taxonomy Database under two prokaryotic codes.

The Genome Taxonomy Database (GTDB) is a taxonomic framework that defines prokaryotic taxa as monophyletic groups in concatenated protein reference trees according to systematic criteria. This has resulted in a substantial number of changes to existing classifications (https://gtdb.ecogenomic.org). In the case of union of taxa, GTDB names were applied based on the priority of publication. The division of taxa or change in rank led to the formation of new Latin names above the rank of genus that were only made publicly available via the GTDB website without associated published taxonomic descriptions. This has sometimes led to confusion in the literature and databases. A number of the provisional GTDB names were later published in other studies, while many still lack authorships. To reduce further confusion, here we propose names and descriptions for 329 GTDB-defined prokaryotic taxa, 223 of which are suitable for validation under the International Code of Nomenclature of Prokaryotes (ICNP) and 49 under the Code of Nomenclature of Prokaryotes described from Sequence Data (SeqCode). For the latter, we designated 23 genomes as type material. An additional 57 taxa that do not currently satisfy the validation criteria of either code are proposed as Candidatus.

Naming genera after geographical locations. Proposal to emend Appendix 9 of the International Code of Nomenclature of Prokaryotes.

Appendix 9, Section E of the International Code of Nomenclature of Prokaryotes provides guidelines on how to form adjectival specific and subspecific epithets that reflect the geographical location where the organism was found or studied. It does not mention ways of naming genera after geographical locations. We here propose emendation of Appendix 9 with the recommendations on how to form such names. Comments on the implementation of the current wording of Appendix 9, Section E are also made.

Guidelines for interpreting the International Code of Nomenclature of Prokaryotes and for preparing a Request for an Opinion.

In this paper the Judicial Commission provides general guidance for interpreting the International Code of Nomenclature of Prokaryotes (ICNP) and specific assistance to authors, reviewers and editors of a Request for an Opinion, or of other suggestions related to the ICNP. The role of the Judicial Commission is recapitulated, particularly with respect to the processing of such Requests. Selected kinds of nomenclature-related proposals are discussed that are unsuitable as the basis for a Request. Particular emphasis is put on Requests for placing names or epithets on the list of nomina rejicienda, and a dichotomous identification key is provided to guide potential authors of a Request that targets the name of a species or subspecies because of issues with its type strain. To this end, the criteria for the valid publication of such names under the ICNP are revisited. Aspects of other kinds of Requests are also addressed. The study is based on a comprehensive review of all Judicial Opinions issued since the publication of the Approved Lists in 1980. One goal of this paper is to assist potential authors in deciding whether their concern should be the subject of a Request, and if so, in composing it with the greatest chance of success. It is also clarified how to obtain additional help regarding nomenclature-related issues.

Hyperactive nanobacteria with host-dependent traits pervade Omnitrophota.

Candidate bacterial phylum Omnitrophota has not been isolated and is poorly understood. We analysed 72 newly sequenced and 349 existing Omnitrophota genomes representing 6 classes and 276 species, along with Earth Microbiome Project data to evaluate habitat, metabolic traits and lifestyles. We applied fluorescence-activated cell sorting and differential size filtration, and showed that most Omnitrophota are ultra-small (~0.2 µm) cells that are found in water, sediments and soils. Omnitrophota genomes in 6 classes are reduced, but maintain major biosynthetic and energy conservation pathways, including acetogenesis (with or without the Wood-Ljungdahl pathway) and diverse respirations. At least 64% of Omnitrophota genomes encode gene clusters typical of bacterial symbionts, suggesting host-associated lifestyles. We repurposed quantitative stable-isotope probing data from soils dominated by andesite, basalt or granite weathering and identified 3 families with high isotope uptake consistent with obligate bacterial predators. We propose that most Omnitrophota inhabit various ecosystems as predators or parasites.

Judicial Opinion 128.

Judicial Opinion 128 addresses nomenclatural issues related to the names of classes validly published under the International Code of Nomenclature of Prokaryotes. It is confirmed that the common ending -proteobacteria of some class names is not indicative of a joint taxonomic or phylogenetic placement; that the nomenclatural type of Mollicutes Edward and Freundt 1967 (Approved Lists 1980) is Mycoplasmatales Freundt 1955 (Approved Lists 1980); and that the placement of a name on the list of rejected names does not imply that another name with the same spelling but a distinct rank is also placed on that list. The names at the rank of class Anoxyphotobacteria (Gibbons and Murray 1978) Murray 1988, Archaeobacteria Murray 1988, Bacteria Haeckel 1894 (Approved Lists 1980), Firmibacteria Murray 1988, Microtatobiotes Philip 1956 (Approved Lists 1980), Oxyphotobacteria (ex Gibbons and Murray 1978) Murray 1988, Photobacteria Gibbons and Murray 1978 (Approved Lists 1980), Proteobacteria Stackebrandt et al. 1988, Schizomycetes Nägeli 1857 (Approved Lists 1980), Scotobacteria Gibbons and Murray 1978 (Approved Lists 1980) are placed on the list of rejected names. For three common nominative singular suffixes of genus names their genitive singular and nominative plural forms are confirmed: -bacter (-bacteris, -bacteres); -fex (-ficis, -fices); and -genes (-genis, -genes). The class names Aquificae Reysenbach 2002, Chrysiogenetes Garrity and Holt 2002, Chthonomonadetes Lee et al. 2011, Gemmatimonadetes Zhang et al. 2003, Opitutae Choo et al. 2007 and Verrucomicrobiae Hedlund et al. 1998 are orthographically corrected to Aquificia, Chrysiogenia, Chthonomonadia, Gemmatimonadia, Opitutia and Verrucomicrobiia, respectively.

Development of the SeqCode: A proposed nomenclatural code for uncultivated prokaryotes with DNA sequences as type.

Over the last fifteen years, genomics has become fully integrated into prokaryotic systematics. The genomes of most type strains have been sequenced, genome sequence similarity is widely used for delineation of species, and phylogenomic methods are commonly used for classification of higher taxonomic ranks. Additionally, environmental genomics has revealed a vast diversity of as-yet-uncultivated taxa. In response to these developments, a new code of nomenclature, the Code of Nomenclature of Prokaryotes Described from Sequence Data (SeqCode), has been developed over the last two years to allow naming of Archaea and Bacteria using DNA sequences as the nomenclatural types. The SeqCode also allows naming of cultured organisms, including fastidious prokaryotes that cannot be deposited into culture collections. Several simplifications relative to the International Code of Nomenclature of Prokaryotes (ICNP) are implemented to make nomenclature more accessible, easier to apply and more readily communicated. By simplifying nomenclature with the goal of a unified classification, inclusive of both cultured and uncultured taxa, the SeqCode will facilitate the naming of taxa in every biome on Earth, encourage the isolation and characterization of as-yet-uncultivated taxa, and promote synergies between the ecological, environmental, physiological, biochemical, and molecular biological disciplines to more fully describe prokaryotes.

SeqCode: a nomenclatural code for prokaryotes described from sequence data.

Most prokaryotes are not available as pure cultures and therefore ineligible for naming under the rules and recommendations of the International Code of Nomenclature of Prokaryotes (ICNP). Here we summarize the development of the SeqCode, a code of nomenclature under which genome sequences serve as nomenclatural types. This code enables valid publication of names of prokaryotes based upon isolate genome, metagenome-assembled genome or single-amplified genome sequences. Otherwise, it is similar to the ICNP with regard to the formation of names and rules of priority. It operates through the SeqCode Registry ( https://seqco.de/ ), a registration portal through which names and nomenclatural types are registered, validated and linked to metadata. We describe the two paths currently available within SeqCode to register and validate names, including Candidatus names, and provide examples for both. Recommendations on minimal standards for DNA sequences are provided. Thus, the SeqCode provides a reproducible and objective framework for the nomenclature of all prokaryotes regardless of cultivability and facilitates communication across microbiological disciplines.

Judicial Opinions 112-122.

Opinion 112 denies the request to place Seliberia Aristovskaya and Parinkina 1963 (Approved Lists 1980) on the list of rejected names because the information provided is insufficient. For the same reason, Opinion 113 denies the request to reject Shewanella irciniae Lee et al. 2006 and Opinion 114 denies the request to reject the name Enterobacter siamensis Khunthongpan et al. 2014. Opinion 115 rejects the epithet of Moorella thermoautotrophica (Wiegel et al. 1981) Collins et al. 1994, which is regarded as a nomen confusum. To assess the consequences of Rule 8, Opinion 116 revisits names of taxa above the rank of genus which should comprise the stem of the name of a nomenclatural type and a category-specific ending but fail to do so. Such names should be orthographically corrected if the sole error is the inadvertent usage of an incorrect stem or be regarded as illegitimate if otherwise. The necessary corrections are made for a number of names. In Opinion 117, the request to designate Methylothermus subterraneus Hirayama et al. 2011 as the type species of the genus Methylothermus is denied because an equivalent action compatible with the Code was already conducted. In Opinion 118, the possible orthographical correction of the name Flaviaesturariibacter is treated, as are the analogous cases of Fredinandcohnia and Hydrogeniiclostidium. The genus names are corrected to Flaviaestuariibacter, Ferdinandcohnia and Hydrogeniiclostridium, respectively. Opinion 119 concludes that assigning Actinomycetales Buchanan 1917 (Approved Lists 1980) as nomenclatural type of the class Actinobacteria Stackebrandt et al. 1997 would not render that name legitimate if Rule 8 remained retroactive. The request is granted but Actinomycetales is also assigned as type of Actinomycetes Krassilnikov 1949 (Approved Lists 1980). In Opinion 120, the possible orthographical correction of the name Amycolatopsis albidoflavus is treated. It is grammatically corrected to Amycolatopsis albidoflava. Six names which could according to Rule 61 be grammatically corrected by anyone are also corrected. Opinion 121 denies the request to revise Opinion 69 and notes that Opinion 69 does not have the undesirable consequences emphasized in the request. In Opinion 122, the request to reject various taxon names of Mollicutes proposed in 2018 is denied because it is based on misinterpretations of the Code, which are clarified. Alternative ways to solve the perceived problems are outlined. These Opinions were ratified by the voting members of the International Committee on Systematics of Prokaryotes.

Judicial Opinions 103-111.

In Opinion 103, the request to place the name Spirillum volutans Ehrenberg 1832 (Approved Lists 1980) on the list of rejected names is denied because a neotype may be designated. Similarly, because a neotype may be designated, in Opinion 104 the request to place the name Beijerinckia fluminensis Döbereiner and Ruschel 1958 (Approved Lists 1980) on the list of rejected names is denied. In Opinion 105, it is emphasized that the name Rhodoligotrophos Fukuda et al. 2012 does not contravene the Code. The request to orthographically correct Rhodoligotrophos Fukuda et al. 2012 to Rhodoligotrophus corrig. Fukuda et al. 2012 is denied. Opinion 106 addresses two Requests for an Opinion and results in the placement of the epithet hoagii in Corynebacterium hoagii (Morse 1912) Eberson 1918 (Approved Lists 1980) and Rhodococcus hoagii (Morse 1912) Kämpfer et al. 2014 on the list of rejected specific and subspecific epithets. Since this removes all known available earlier synonyms of Rhodococcus equi (Magnusson 1923) Goodfellow and Alderson 1977 (Approved Lists 1980), the request to conserve the epithet equi in this name is denied. In Opinion 107, Thermomicrobium fosteri Phillips and Perry 1976 (Approved Lists 1980) is placed on the list of rejected names as a nomen dubium et confusum. Opinion 108 denies the request to place Hyphomonas rosenbergii Weiner et al. 2000 on the list of rejected names because the information provided to the Judicial Commission is not sufficient to draw a conclusion on this matter. In Opinion 109, which addresses three Requests for an Opinion, the Judicial Commission denies the requests to place the names Bacillus aerius Shivaji et al. 2006, Bacillus aerophilus Shivaji et al. 2006 and Bacillus stratosphericus Shivaji et al. 2006 on the list of rejected names. Instead, it is concluded that these three names had not met the requirements for valid publication. Likewise, the Judicial Commission concludes in Opinion 110 that the name Actinobaculum massiliense corrig. Greub and Raoult 2006 had not met the requirements for valid publication. The Judicial Commission reaffirms in Opinion 111 that Methanocorpusculum parvum Zellner et al. 1988 is the nomenclatural type of Methanocorpusculum Zellner et al. 1988 and further emphasizes that the species was not in danger of losing this status. These Opinions were ratified by the voting members of the International Committee on Systematics of Prokaryotes.

GTDB: an ongoing census of bacterial and archaeal diversity through a phylogenetically consistent, rank normalized and complete genome-based taxonomy.

The Genome Taxonomy Database (GTDB; https://gtdb.ecogenomic.org) provides a phylogenetically consistent and rank normalized genome-based taxonomy for prokaryotic genomes sourced from the NCBI Assembly database. GTDB R06-RS202 spans 254 090 bacterial and 4316 archaeal genomes, a 270% increase since the introduction of the GTDB in November, 2017. These genomes are organized into 45 555 bacterial and 2339 archaeal species clusters which is a 200% increase since the integration of species clusters into the GTDB in June, 2019. Here, we explore prokaryotic diversity from the perspective of the GTDB and highlight the importance of metagenome-assembled genomes in expanding available genomic representation. We also discuss improvements to the GTDB website which allow tracking of taxonomic changes, easy assessment of genome assembly quality, and identification of genomes assembled from type material or used as species representatives. Methodological updates and policy changes made since the inception of the GTDB are then described along with the procedure used to update species clusters in the GTDB. We conclude with a discussion on the use of average nucleotide identities as a pragmatic approach for delineating prokaryotic species.

Judicial Opinions 123-127.

Opinion 123 places the epithet of the name Aeromonas punctata on the list of rejected epithets and clarifies the citation of authors of selected names within the genus Aeromonas. Opinion 124 denies the request to place Borreliella on the list of rejected names because the request is based on a misinterpretation of the Code, which is clarified. There are alternative ways to solve the perceived problem. Opinion 125 denies the request to place Lactobacillus fornicalis on the list of rejected names because the provided information does not yield a reason for rejection. Opinion 126 denies the request to place Prolinoborus and Prolinoborus fasciculus on the list of rejected names because a relevant type strain deposit was not examined. Opinion 127 grants the request to assign the strain deposited as ATCC 4720 as the type strain of Agrobacterium tumefaciens, thereby correcting the Approved Lists. These Opinions were ratified by the voting members of the International Committee on Systematics of Prokaryotes.

A standardized archaeal taxonomy for the Genome Taxonomy Database.

The accrual of genomic data from both cultured and uncultured microorganisms provides new opportunities to develop systematic taxonomies based on evolutionary relationships. Previously, we established a bacterial taxonomy through the Genome Taxonomy Database. Here, we propose a standardized archaeal taxonomy that is derived from a 122-concatenated-protein phylogeny that resolves polyphyletic groups and normalizes ranks based on relative evolutionary divergence. The resulting archaeal taxonomy, which forms part of the Genome Taxonomy Database, is stable for a range of phylogenetic variables including marker gene selection, inference methods, corrections for rate heterogeneity and compositional bias, tree rooting scenarios and expansion of the genome database. Rank normalization is shown to robustly correct for substitution rates varying up to 30-fold using simulated datasets. Taxonomic curation follows the rules of the International Code of Nomenclature of Prokaryotes while taking into account proposals to formally recognize the rank of phylum and to use genome sequences as type material. This taxonomy is based on 2,392 archaeal genomes, 93.3% of which required one or more changes to their existing taxonomy, mainly owing to incomplete classification. We identify 16 archaeal phyla and reclassify 3 major monophyletic units from the former Euryarchaeota and one phylum that unites the Thaumarchaeota-Aigarchaeota-Crenarchaeota-Korarchaeota (TACK) superphylum into a single phylum.