Advancements in prokaryotic systematics and the role of Bergey's International Society for Microbial Systematicsin addressing challenges in the meta-data era.

Prokaryotes are ubiquitous in the biosphere, important for human health and drive diverse biological and environmental processes. Systematics of prokaryotes, whose origins can be traced to the discovery of microorganisms in the 17th century, has transitioned from a phenotype-based classification to a more comprehensive polyphasic taxonomy and eventually to the current genome-based taxonomic approach. This transition aligns with a foundational shift from studies focused on phenotypic traits that have limited comparative value to those using genome sequences. In this context, Bergey's Manual of Systematics of Archaea and Bacteria (BMSAB) and Bergey's International Society for Microbial Systematics (BISMiS) play a pivotal role in guiding prokaryotic systematics. This review focuses on the historical development of prokaryotic systematics with a focus on the roles of BMSAB and BISMiS. We also explore significant contributions and achievements by microbiologists, highlight the latest progress in the field and anticipate challenges and opportunities within prokaryotic systematics. Additionally, we outline five focal points of BISMiS that are aimed at addressing these challenges. In conclusion, our collaborative effort seeks to enhance ongoing advancements in prokaryotic systematics, ensuring its continued relevance and innovative characters in the contemporary landscape of genomics and bioinformatics.

Cultivation of novel Atribacterota from oil well provides new insight into their diversity, ecology, and evolution in anoxic, carbon-rich environments.

BACKGROUND: The Atribacterota are widely distributed in the subsurface biosphere. Recently, the first Atribacterota isolate was described and the number of Atribacterota genome sequences retrieved from environmental samples has increased significantly; however, their diversity, physiology, ecology, and evolution remain poorly understood. RESULTS: We report the isolation of the second member of Atribacterota, Thermatribacter velox gen. nov., sp. nov., within a new family Thermatribacteraceae fam. nov., and the short-term laboratory cultivation of a member of the JS1 lineage, Phoenicimicrobium oleiphilum HX-OS.bin.34TS, both from a terrestrial oil reservoir. Physiological and metatranscriptomics analyses showed that Thermatribacter velox B11T and Phoenicimicrobium oleiphilum HX-OS.bin.34TS ferment sugars and n-alkanes, respectively, producing H2, CO2, and acetate as common products. Comparative genomics showed that all members of the Atribacterota lack a complete Wood-Ljungdahl Pathway (WLP), but that the Reductive Glycine Pathway (RGP) is widespread, indicating that the RGP, rather than WLP, is a central hub in Atribacterota metabolism. Ancestral character state reconstructions and phylogenetic analyses showed that key genes encoding the RGP (fdhA, fhs, folD, glyA, gcvT, gcvPAB, pdhD) and other central functions were gained independently in the two classes, Atribacteria (OP9) and Phoenicimicrobiia (JS1), after which they were inherited vertically; these genes included fumarate-adding enzymes (faeA; Phoenicimicrobiia only), the CODH/ACS complex (acsABCDE), and diverse hydrogenases (NiFe group 3b, 4b and FeFe group A3, C). Finally, we present genome-resolved community metabolic models showing the central roles of Atribacteria (OP9) and Phoenicimicrobiia (JS1) in acetate- and hydrocarbon-rich environments. CONCLUSION: Our findings expand the knowledge of the diversity, physiology, ecology, and evolution of the phylum Atribacterota. This study is a starting point for promoting more incisive studies of their syntrophic biology and may guide the rational design of strategies to cultivate them in the laboratory. Video Abstract.

Genome-based analysis of the family Paracoccaceae and description of Ostreiculturibacter nitratireducens gen. nov., sp. nov., isolated from an oyster farm on a tidal flat.

Two bacterial strains, designated FR2A1T and MT2-5-38, were isolated from the surface sediments of an oyster farm on a tidal flat in Quanzhou Bay, China. Both strains were Gram-stain-negative, rod-shaped, aerobic, catalase-positive, and oxidase-positive. The 16S rRNA gene sequences of the two strains were 100% identical and had the highest similarity (97.1%) with Phaeovulum vinaykumarii JA123T. The average nucleotide identity (ANI) value and digital DNA-DNA hybridization (DDH) value indicated that the two strains belonged to a single species. Gene annotation revealed that the two strains contained a gene cluster for nitrate reduction and a gene cluster for sulfur oxidation, indicating a possible role in N and S cycling in the tidal flat sediment. The phylogeny inferred from the 16S rRNA gene and 120 conserved proteins indicated that the two strains formed a distinct monophyletic clade within the family Paracoccaceae. The respiratory quinone was Q-10. The major fatty acids consisted of summed feature 8 (C18:1ω7c and/or C18:1ω6c) and C18:0. The polar lipids consisted of phosphatidylethanolamine, phosphatidylglycerol, and several unidentified phospholipids. Based on the above characteristics, strains FR2A1T and MT2-5-38 represent a novel genus and a novel species, for which we propose the name Ostreiculturibacter nitratireducens gen. nov., sp. nov. The type strain is FR2A1T (=MCCC 1K08809T = KCTC 8317T). Phylogenomic analysis of 1,606 high-quality genomes of the family Paracoccaceae, including type strains, non-type strains, and uncultivated bacteria, was performed using the Genome Taxonomic Database Toolkit (GTDB-Tk), and the average amino acid identity (AAI) value of the phylogenetic clade was estimated. We found that 35 species of the family Paracoccaceae needed re-classification, and an AAI value of 70% was chosen as the genus boundary within the family Paracoccaceae.

Proposal of Shuttleworthella gen. nov. and Nostocoides gen. nov. as replacement names for the illegitimate prokaryotic generic names Shuttleworthia and Tetrasphaera, respectively.

The prokaryotic generic name Shuttleworthia Downes et al. 2002 is illegitimate because it is a later homonym of the plant genus Shuttleworthia Meisner 1840 and the mollusk genus Shuttleworthia Baker 1941 (Principle 2 and Rule 51b(5) of the International Code of Nomenclature of Prokaryotes). We therefore propose the replacement generic name Shuttleworthella, with type species Shuttleworthella satelles comb. nov. The prokaryotic generic name Tetrasphaera Maszenan et al. 2000 is illegitimate because it is a later homonym of Tetrasphaera Popofsky 1913 (Protozoa, Radiolaria) and of Tetrasphaera Górka 1965 (a fossil dinoflagellate) (Rule 51b(4) of the International Code of Nomenclature of Prokaryotes). We therefore propose the replacement generic name Nostocoides, with type species Nostocoides japonicum comb. nov.

Proposals to revise the Statutes of the International Committee on Systematics of Prokaryotes.

The International Committee on Systematics of Prokaryotes serves to administer the rules of prokaryotic nomenclature via the International Code of Nomenclature of Prokaryotes, ensures the publication of the International Journal of Systematic and Evolutionary Microbiology, and works to represent the interests of the microbiological disciplines regarding prokaryotic nomenclature. The functions and mechanisms of operation of the International Committee on Systematics of Prokaryotes (ICSP) are defined in its Statutes, which were last revised in 2019. As members of the 2020-2023 and the 2023-2026 ICSP Executive Board and the Judicial Commission, we propose here some further revisions to help improve the clarity and functionality of the Statutes.

Proposed minimal standards for description of new taxa of the class Halobacteria.

Halophilic archaea of the class Halobacteria are the most salt-requiring prokaryotes within the domain Archaea. In 1997, minimal standards for the description of new taxa in the order Halobacteriales were proposed. From then on, the taxonomy of the class Halobacteria provides an excellent example of how changing concepts on prokaryote taxonomy and the development of new methods were implemented. The last decades have witnessed a rapid expansion of the number of described taxa within the class Halobacteria coinciding with the era of genome sequencing development. The current members of the International Committee on Systematics of Prokaryotes Subcommittee on the Taxonomy of Halobacteria propose these revisions to the recommended minimal standards and encourage the use of advanced technologies in the taxonomic description of members of the Halobacteria. Most previously required and some recommended minimal standards for the description of new taxa in the class Halobacteria were retained in the present revision, but changes have been proposed in line with the new methodologies. In addition to the 16S rRNA gene, the rpoB' gene is an important molecular marker for the identification of members of the Halobacteria. Phylogenomic analysis based on concatenated conserved, single-copy marker genes is required to infer the taxonomic status of new taxa. The overall genome relatedness indexes have proven to be determinative in the classification of the taxa within the class Halobacteria. Average nucleotide identity, digital DNA-DNA hybridization, and average amino acid identity values should be calculated for rigorous comparison among close relatives.

Reclassification of Allomuricauda and Muricauda species as members of the genus Flagellimonas Bae et al. 2007 and emended description of the genus Flagellimonas.

The recently proposed genus Allomuricauda Deshmukh and Oren 2023 is illegitimate because it includes the type species of the genera Flagellimonas Bae et al. 2007 and Spongiibacterium Yoon and Oh 2012, contravening Rule 51b(1) of the International Code of Nomenclature of Prokaryotes. As Flagellimonas Bae et al. 2007 is the earlier described genus, we here reclassify 36 species earlier described as belonging to the illegitimate genus Muricauda as species of Flagellimonas. We also present an emended description of the genus Flagellimonas.