International Journal of Systematic and Evolutionary Microbiology

The alphaproteobacterial order Hyphomicrobiales consists of 38 families comprising 155 validly published genera as of June 2023. The order Hyphomicrobiales was first described in 1957 and underwent important revisions in 2020. However, several inconsistencies in the taxonomy of this order remain, and there is a need for a consistent framework for defining families within the order. We propose a common genome-based framework for defining families within the order Hyphomicrobiales, suggesting that families represent monophyletic groups in core-genome phylogenies that share pairwise average amino acid identity values above [~]75% when calculated from a core set of 59 proteins. Applying this framework, we propose the formation of four new families and to reassign the genera Salaquimonas, Rhodoblastus, and Rhodoligotrophos into Salaquimonadaceae fam. nov., Rhodoblastaceae fam. nov., and Rhodoligotrophaceae fam. nov., respectively, and the genera Albibacter, Chenggangzhangella, Hansschlegelia, and Methylopila into Methylopilaceae fam. nov.. We further propose to unify the families Bartonellaceae, Brucellaceae, Phyllobacteriaceae, and Notoacmeibacteraceae as Bartonellaceae; the families Segnochrobactraceae and Pseudoxanthobacteraceae as Segnochrobactraceae; the families Lichenihabitantaceae and Lichenibacteriaceae as Lichenihabitantaceae; and the families Breoghaniaceae and Stappiaceae as Stappiaceae. Lastly, we propose to reassign several genera to existing families. Specifically, we propose to reassign the genus Pseudohoeflea to the family Rhizobiaceae; the genera Oricola, Roseitalea, and Oceaniradius to the family Ahrensiaceae; the genus Limoniibacter to the emended family Bartonellaceae; the genus Faunimonas to the family Afifellaceae; and the genus Pseudochelatococcus to the family Chelatococcaceae. Our data also support the recent proposal to reassign the genus Prosthecomicrobium to the family Kaistiaceae.

Strains of two novel Corynebacterium species were cultured from samples of human nostrils and skin collected in the United States and Botswana. These strains demonstrated growth on Columbia Colistin-Nalidixic Acid agar with 5% sheep blood and in liquid media (brain heart infusion and tryptic soy broth) supplemented with Tween 80, a source of the fatty acid oleic acid. Cells were Gram-positive, non-spore-forming, non-motile bacilli that showed catalase but not oxidase activity. Major fatty acids in both of these species were 18:1 {omega}9c (oleic acid), 16:0 (palmitic acid), and 18:0 (stearic acid). Analysis of the 16S ribosomal RNA gene sequences identified these strains as belonging to the genus Corynebacterium (family Corynebacteriaceae). Whole-genome sequencing revealed that these strains formed distinct branches on a phylogenomic tree, with C. tuberculostearicum being the closest relative but with average nucleotide identities of < 95% relative to all previously described species. These results indicate that these strains represent novel species of Corynebacterium, for which we propose the names Corynebacterium hallux sp. nov., with the type strain CTNIH22T (=ATCC TSD-435T=DSM 117774T), and Corynebacterium nasorum sp. nov., with the type strain KPL3804T (=ATCC TSD-439T=DSM 117767T). We also describe the characteristics of two strains isolated from human nasal passages that are members of the recently named species Corynebacterium yonathiae. RepositoriesThe sequencing files supporting the conclusions of this study are available in the Sequence Read Archive (PRJNA804245, PRJNA854648, PRJNA842433). The partial 16S ribosomal RNA gene sequences from PCR amplification and Sanger sequencing are available in GenBank for Corynebacterium hallux sp. nov. CTNIH22T (accession number: PQ252679) and Corynebacterium nasorum sp. nov. KPL3804T (accession number: PQ149068). The annotated genomic sequences for the strains characterized in this study have been deposited in GenBank with the following accession numbers: C. hallux sp. nov. CTNIH22T (GCF_032821755.1), C. nasorum sp. nov. KPL3804T (GCF_037908315.1), C. nasorum sp. nov. MSK185 (GCF_030229765.1), C. yonathiae KPL2619 (GCF_037908465.1), and C. yonathiae MSK136 (GCF_022288805.2).

Three new Curtobacterium species from healthy tissues of agricultural crop plants in the United States are reported. They are Curtobacterium glycinis sp. nov. from soybean in Missouri, Curtobacterium gossypii from cotton in Puerto Rico and corn in Missouri, and Curtobacterium oryzae sp. nov. from rice in Texas.

Five novel species from healthy plants and other substrates are described. These are Paenibacillus glycinicola sp. nov. from Glycine max in Iowa, United States; Paenibacillus triticicola sp. nov. from Triticum aestivum in Australia, Allium cepa in Texas, garden soil in Wisconsin, cows milk in New York state, Panicum virgatum in Michigan, sweet sorghum in Nebraska, and Zea mays in Ohio; Pseudescherichia oryzae sp. nov. from Oryza sativa in Arkansas; Pseudomonas gossypii sp. nov. from a healthy Bos taurus in Kansas, Capsicum annuum from Arizona, Gossypium hirsutum in New Mexico, Oklahoma, and Texas, and Zea mays from Arkansas; and Tardiphaga zeae sp. nov. from Zea mays in Iowa. No pathogenic strains are known for any of the novel species.

Recently Hordt et al. 2020 proposed to merge Ochrobactrum and Brucella genera based on up to date phylogenomic evidence and overall genomic divergence among Brucella-Ochrobactrum clade. This led to the description of the new combinations Brucella ciceri comb. nov., basonym: Ochrobactrum ciceri Imran et al. 2010 and Brucella intermedia comb. nov., basonym: Ochrobactrum intermedium Velasco et al. 1998. However, the type species for Brucella ciceri DSM 22292T and Brucella intermedia LMG 3301T show whole-genome coherence at the species level (ANI = 98.21 %, Mash D = 0.0154006, dDDH relatedness >70%), suggesting that may belong to the same genomospecies. Also, both taxa formed a single clade in the phylogenomic tree based on single-copy gene sequences. Previously reported phenotypic data offer a context where both taxa are highly related supporting this synonymy. Therefore, Brucella ciceri should be reclassified as later heterotypic synonyms of Brucella intermedia, which has priority. The species description is consequently amended.

Streptomycetaceae is one of the oldest families within phylum Actinobacteria and it is large and diverse in terms of number of described taxa. The members of the family are known for their ability to produce medically important secondary metabolites and antibiotics. In this study, strains showing low 16S rRNA gene similarity (&lt;97.3 %) with other members of Streptomycetaceae were identified and subjected to phylogenomic analysis using 33 orthologous gene clusters (OGC) for accurate taxonomic reassignment resulted in identification of eight distinct and deeply branching clades, further average amino acid identity (AAI) analysis showed lower AAI values or AAI within the range of 60-80 % which was previously observed in related but different genera of bacteria. The whole genome phylogeny based on concatenated core genes and AAI analyses supported the claim that those phylogenetically distinct members may be assigned to 8 novel genera namely Actinoacidiphila, Actinomesophilus, Charcoactinospora, Curviacidiphilus, Kafeoacidiphilus, Mangroviactinospora, Peterkaempfera, and Streptantibioticus. In addition, based on the core genome phylogeny and 16S rRNA tree topology and distinct chemotaxonomic and physiological properties, the sequence belonged to Streptomyces thermoautotrophicus was assigned to a novel genera Charcoactinospora which is placed under novel family Charcoactinosporaceae. Lastly, a clade comprising of strains that showed high 16S rRNA gene similarity (100 %) with similar tree topology in phylogenetic trees was subjected to overall genome related indices analyses such as digital DNA – DNA hybridization, and average nucleotide identity that supported the claim that Streptomyces asterosporus is a later heterotypic synonym of Streptomyces calvus.Competing Interest StatementThe authors have declared no competing interest.AbbreviationsOGCOrthologous gene clusterAAIaverage amino acid identitydDDHdigital DNA-DNA hybridizationANIaverage nucleotide identityView Full Text

Four rhizobial strains isolated from root nodules of tropical leguminous plants in Costa Rica were characterized. Strain LEGMi-135b was isolated from Lonchocarpus felipei root nodules, LEGMi-12c from Cojoba arborea, LEGMi-198b from Calliandra haematocephala and Rhizobium altiplani LEGMi-166a from Mimosa pigra. Phylogenetic analyses based on the 16S rRNA gene and four concatenated housekeeping genes (recA, atpD, GATase and gyrB) placed these strains within the genera Martinezella (LEGMi-12c, LEGMi-135b, and LEGMi-198b) and Rhizobium (LEGMi-166a). Genome-based analyses showed that strain LEGMi-135b exhibited an average nucleotide identity (ANI) value of 94% and a digital DNA-DNA hybridization (dDDH) value of 53.2% compared with its closest related species, Martinezella hainanensis CCBAU 57015T, supporting its classification as a distinct species. LEGMI-12c exhibited ANI and dDDH values of 98% and 87%, respectively, compared with Martinezella hainanensis CCBAU 57015T. LEGMi-198b showed the highest similarity to Rhizobium cerradonense CNPSo 3464, with ANI and dDDH values of 98% and 81.4%, respectively; however, this taxon has not been validly published. LEGMi-166a exhibited ANI and dDDH values of 100% and 99.3%, respectively, compared with Rhizobium altiplani BR 10423, confirming its assignment to this species. Additionally, differentiation of strains LEGMi-135b and LEGMi-198b from their closest phylogenetic relatives was supported by phenotypic, physiological, and biochemical analyses. Based on the combined genomic, phenotypic, and biochemical evidence, we propose the establishment of the novel rhizobial species Martinezella legmii sp. nov., with strain LEGMi-135b designated as the type strain (LEGMi-135b), and Martinezella ivanii sp. nov., with strain LEGMi-198b designated as the type strain (LEGMi-198b). This study expands our understanding of rhizobial diversity associated with nitrogen-fixing symbioses, particularly among tropical leguminous plants from Costa Rica

A phylogenetic study of Anoxybacillus, Geobacillus and Parageobacillus was performed using publicly available whole genome sequences. A total of 113 genomes were selected for phylogenomic metrics including calculation of Average Nucleotide Identity (ANI) and Average Amino acid Identity (AAI), and a maximum likelihood tree was built from alignment of a set of 662 orthologous core genes. The combined results from the core gene tree and ANI and AAI dendrograms show that the genomes split into two main clades, clade I containing all Geobacillus, all Parageobacillus and some species of Anoxybacillus, and clade II, containing the majority of Anoxybacillus species. Clade I is further partitioned into three clades, consisting separately of Geobacillus, Parageobacillus, and a third clade which we suggest should be elevated to a new genus Quasigeobacillus gen. nov. Two species of Anoxybacillus showed inconsistent positioning among the trees produced by differing methods and could not be clearly resolved into any of the three existing genera or the new genus. This research shows the importance of considering closely related genera together when studying phylogeny or assigning genomic affinities.

The Pectobacteriaceae family comprises plant pathogens able to provoke diverse diseases, including plant maceration due to the production of pectinases disrupting the plant cell wall. To better understand their natural diversity, a survey of pectinolytic bacteria was performed in lakes of the French region La Camargue near the Mediterranean Sea. Sixteen atypical pectinolytic isolates were obtained from brackish water of three lakes. The genome of six isolates was sequenced; their size is around 4.8 to 5.0 Mb, including a plasmid of 59 to 61 kb; their G+C values range from 49.1 to 49.3 mol%. Phylogenetic analyses indicated that the novel strains formed a new clade of Pectobacteriaceae, separate from previously described genera of this family. These analyses suggested also that Acerihabitans does not belong to Pectobacteriaceae and should be reclassified in the Bruguierivoracaceae family, while Symbiopectobacterium could be a true Pectobacteriaceae member. Based on phenotypic, genomic and phylogenetic characteristics, we propose the creation of a new genus with the name Prodigiosinella gen. nov. Both the phenotypic and phylogenetic analyses separated the strains into two distinct subgroups. However, the DNA-DNA relatedness values revealed a close relationship between the two groups, supporting their appurtenance to the same species. Thus, it is proposed to classify them as two subspecies of Prodigiosinella aquatilis sp. nov., for which we propose the name Prodigiosinella aquatilis subsp. aquatilis ssp. nov. (LS101T = CFBP 8826T = LMG 32072T) and Prodigiosinella aquatilis subsp. natabilis ssp. nov. (CE70T = CFBP 9054T = LMG 32867T).

We present the description of the new species, Rhodococcus (Prescottella) parequi, found during phylogenomic investigations of a global collection of strains identified as Rhodococcus (Prescottella) equi. Strain PAM 2766 was isolated from horse-breeding farm soil in Normandy, France, and was indistinguishable from R. equi based on the usual identification tests. Whole-genome phylogenetic analyses located PAM 2766 in the same Rhodococcus sublineage as R. equi, together with Rhodococcus agglutinans, Rhodococcus defluvii, Rhodococcus soli, Rhodococcus subtropicus, Rhodococcus spongiicola and Rhodococcus xishaensis. PAM 2766 is most closely related to, but sufficiently distinct from R. equi DSM 20307T to be considered as a separate species. Average Nucleotide Identity (ANI) and Average Amino Acid Identity (AAI) values are 88.60% and 92.35, respectively, well below the species cutoff. The PAM 2766 draft genome is [~]5.3 Mb in size with 68.98% G+C mol content. PAM 2766T is aerobic, non-motile, and produces smooth creamy to buff-coloured colonies very similar to those of R. equi. It phenotypically differs from the latter by the ability to grow at 5{degrees}C, a strongly positive urease test at 24 h, and specificities in the carbon and nitrogen source utilization profile as determined by phenotype microarray screens. Our data indicate that PAM 2766 belongs to a novel species, for which the name Rhodococcus parequi sp. nov. is proposed. R. parequi was avirulent in macrophage infection assays and is assumed to be non-pathogenic. The type strain is PAM 2766T (=CETC 30995T = NCTC 14987T).

Strain LLG6346-3.1T, isolated from the thallus of the brown alga Ericaria zosteroides collected in Mediterranean Sea near Bastia in Corsica, France, was characterized using a polyphasic method. Cells were Gram-stain-negative, strictly aerobic, non-flagellated, motile by gliding, rod-shaped and grew optimally at 30-33 {degrees}C, at pH 8-8.5 and with 4-5 % NaCl. Strain LLG6346-3.1T used the seaweed polysaccharide alginic acid as sole carbon source which was vigorously liquefied. Phylogenetic analyses showed that the bacterium is affiliated to the genus Zobellia (family Flavobacteriaceae, class Flavobacteriia). Strain LLG6346-3.1T exhibited 16S rRNA gene sequence similarity values of 98.5 and 98.3 % to the type strains of Zobellia russellii and Zobellia roscoffensis respectively, and of 97.4-98.2 % to other species of the genus Zobellia. The DNA G+C content of strain LLG6346-3.1T was determined to be 38.28 mol%. Digital DNA-DNA hybridization predictions by the ANI and GGDC methods between strain LLG6346-3.1T and other members of the genus Zobellia showed values of 76-88 %, and below 37 %, respectively. The phenotypic, phylogenetic and genomic analyses show that strain LLG6346-3.1T is distinct from species of the genus Zobellia with validly published names and that it represents a novel species of the genus Zobellia, for which the name Zobellia alginoliquefaciens sp. nov. is proposed. The type strain is LLG6346-3.1T (RCC 7657T = LLG 32918T).

A Gram-stain-negative, aerobic, moderately halophilic, non-motile, rod-shaped bacterium, designated MC10-B4T, was isolated from the coral Oulastrea crispata collected from Hong Kong waters. The strain showed the ability to persist in a coral holobiont during an eight-month monitoring period in a field trial, indicating a long-term association with the coral host. Growth occurred at 10-37 {degrees}C (optimum, 28-30 {degrees}C), at NaCl concentrations up to 4.0% (w/v; optimum, 0.5-2.0%), and at pH 7.0-10.0 (optimum, pH 7.0-8.0) under standard laboratory conditions. Colonies on Marine Agar 2216 were round, smooth, convex, white, opaque, and had entire margins. Phylogenetic analysis based on 16S rRNA gene sequences indicated that strain MC10-B4T belongs to the genus Ruegeria and shares the highest sequence similarity with Ruegeria conchae TW15T (99.64%), followed by Ruegeria profundi ZGT108T (98.92%), Ruegeria lacuscaerulensis ITI-1157T (98.46%), Ruegeria denitrificans CECT 5091T (98.31%), Ruegeria arenilitoris G-M8T (97.69%), Ruegeria atlantica NBRC 15792T (97.55%), Ruegeria halocynthiae MA1-6 (97.11%), Ruegeria atlantica IAM 14463T (96.98%), Ruegeria meonggei MA-E2-3 (96.83%), and Ruegeria pomeroyi DSS-3T (96.65%). Genome sequencing revealed a genome size of 4.55 Mbp and a DNA G+C content of 57.5 mol%. The average nucleotide identity and digital DNA-DNA hybridization values between strain MC10-B4T and Ruegeria conchae TW15T were 77.6% and 18.2-22.8%, respectively. These values are below the recommended thresholds for species delineation (95% and 70%). Strain MC10-B4T shares the same predominant fatty acid, summed feature 8 (consisting of C18:1 {omega}7c and/or C18:1 {omega}6c), with other Ruegeria strains; however, it also contains C19:0 cyclo {omega}8c, which was not detected in Ruegeria conchae TW15T and Ruegeria pomeroyi DSS-3T. The type strain is MC10-B4T (= GDMCC 1.6889T = KCTC 18785T).

A novel bacterial strain designated ADMK78T was isolated from the saline desert soil. The cells were rod-shaped, Gram-negative, and non-motile. The strain ADMK78T grows best at 28{degrees}C and pH 7.0 and can tolerate up to 2% (w/v) NaCl. Based on 16S rRNA gene phylogeny, the strain ADMK78T belongs to the genus Rhizobium, with the highest similarity to Rhizobium wuzhouense W44T (98.7%) and Rhizobium ipomoeae shin9-1T (97.9%). Core-genes based phylogenetic analysis revealed that the strain ADMK78T forms a distinct branch in between Rhizobium ipomoeae shin9-1T and Rhizobium selenitireducens BAA-1503T. The average nucleotide identity of ADMK78T was less than 82%, to members of the family Rhizobiaceae. The genomic DNA G+C content of strain ADMK78T is 58.6 mol%. The major fatty acids of strain ADMK78T were C18:0 and C18:1 {omega}7c. The strain ADMK78T showed differences in physiological, phenotypic, and protein profiles estimated by MALDI-TOF MS to its closest relatives. Based on the phenotypic, chemotaxonomic properties, and phylogenetic analyses, the strain ADMK78T could be distinguished from the recognized species of the genus Rhizobium. It is suggested to represent a novel species of this genus, for which the name Rhizobium desertarenae sp. nov. is proposed. The type strain is ADMK78T (=MCC 3400T; KACC 21383T; JCM 33657T).

Bradyrhizobia are widespread across the Australian continent, where they are essential to Australian ecosystems by helping legumes to compensate nutrient deficiencies and low fertility of Australian soils. Among the Bradyrhizobium genospecies identified during a survey of Australian native rhizobia communities in 1994-1995, genospecies L appeared to be only distantly related to any Bradyrhizobium lineages known at the time. We take advantage of the recent sequencing of the genome of strain BDV5419, the original strain corresponding to Bradyrhizobium genospecies L, to re-assess this lineage taxonomic status. We characterized further strain BDV5419 based on morpho-physiological traits and determined its phylogenetic relationships with the type strains of the 88 currently known Bradyrhizobium species based on sequence comparisons of SSU rRNA genes and complete genomes. The digital DNA-DNA hybridization relatedness with any type strain was less than 33% and both SSU rRNA gene and genome phylogenies confirmed that this strain does not belong to any formerly described species within the Bradyrhizobium genus. Whereas its position within the lineage encompassing the B. elkanii and B. jicamae supergroups is unresolved in the SSU rDNA phylogeny, strain BDV5419 appears to be one of most basal lineages of the B. elkanii supergroup in the genome comparison. All data thus support the description of the novel species Bradyrhizobium hardenbergiae sp. nov. which type strain is BDV5419T (= CFBP 9111T = LMG 32897T), isolated from a nodule of Hardenbergia violaceae in Black Mountain Nature Reserve, in Canberra, ACT, Australia.

Members of Phytobacter, a recently described genus within the family Enterobacteriaceae, are still frequently misclassified as species of other genera. Here, we present genomic evidence that the taxa "Citrobacter bitternis" and "Kluyvera intestini", as cited in the literature and listed in NCBI databases, are heterotypic synonyms of Phytobacter diazotrophicus. Comparative analyses of 16S rRNA gene phylogeny, core genome phylogeny, average nucleotide identity (ANI), and digital DNA-DNA hybridization (dDDH) consistently place the type strains of both "C. bitternis" and "K. intestini" within the species P. diazotrophicus. Recognizing these taxa as synonyms will help resolve persistent taxonomic inconsistencies and reduce misidentification in clinical and environmental microbiology.

Pectobacterium comprises Gram-negative, pectinolytic plant pathogens that cause soft rot and blackleg diseases on numerous economically important crops. During sampling in 2018 in taro (Colocasia esculenta) fields in Hawaii, two bacterial strains PL152T and PL155 were isolated from taro. Peliminary molecular characterization placed both strains in the genus Pectobacterium. However, their taxanomic postions could not be resoved at the species level. A polyphasic taxonomic approach incorporating phenotypic characterization, 16S rRNA gene sequence analysis, multilocus sequence analysis (MLSA), whole genome based phylogeny, average nucleotide identity (ANI), and digital DNA-DNA hybridization (dDDH) was therefore employed to determine their taxonomic status. Phylogenetic and phylogenomic analyses consistently placed PL152 and PL155 together in a distinct and well supported lineage within the genus Pectobacterium, separate from currently recognized species. The two strains exhibited high genomic relatedness to each other, whereas the average nucleotide identity (ANI) and digital DNA-DNA hybridization (dDDH) values, were lower than the accepted species delineation thresholds of 95% and 70%, respectively, supported the delineation of a novel bacterial species. The genomic characteristic of PL152 included a genome size of 5.02 Mb and a DNA G+C content of 52%. Collectively, based on a polyphasic approach including phylogenetic, phlyogenomic, biochemical, and phenotypic evidences supports the classification of strains PL152 and PL155 as representatives of a novel species within the genus Pectobacterium, for which the name Pectobacterium pacificum sp. nov. is proposed. Strain PL152 (ICMP 2436274, LMG 32536) is designated as the type strain.

Six strains of a novel anaerobic bacterial taxa exhibiting bile acid-transforming activity were isolated from fecal samples of clinically healthy cats living in Oakland, California. 16S rRNA sequencing and phylogenetic analysis indicate that strain AB800T belongs to the genus Peptacetobacter, with Peptacetobacter hiranonis strain JCM 10541 (98% coverage, 99.7% identity) as its closest relative. Whole genome sequencing shows an average nucleotide identity (ANI) of less than 96% (95.73% ANI, 90.53% AF) with the closest validly named species being Peptacetobacter hiranonis DGF055142. The size is about 2.58 Mb, containing 2,355 predicted coding sequences and 2,450 annotated genes. Phenotypic characterisation, and comprehensive genomic analysis, including ANI, digital DNA-DNA hybridization (dDDH) and core genome phylogenetic analysis, placing the strain AB800T on a separate branch, supported the classification of a novel species, strain AB800T (DSM 120482 = LMG 34035) with the proposed name Candidatus Peptacetobacter felis sp. nov., derived from "felis" the latin name of cat felis catus. These findings expand our understanding of host-associated bile acid converters and provide promising candidates for probiotic development.

Four novel bacterial species collected from healthy tissues of corn, rice and soybean plants in the United States are described. These include Cellulomonas zeae sp. nov. isolated from corn in Indiana; Lelliottia zeae sp. nov. from corn in Indiana and rice in Arkansas; Paraburkholderia zeae sp. nov. isolated from corn in Iowa; and Sphingomonas zeigerminis sp. nov. from corn in Mississippi and soy in Arkansas. No pathogenic strains are known for any of the novel species based on genome comparisons to assemblies in GenBank.

A strictly anaerobic bacterial strain, F2T, was isolated from an anaerobic bioreactor fermenting source-separated organic waste. Cells of strain F2T are non-spore-forming, rod-shaped (1.5-2.5 x 0.27-0.33 m), and Gram-negative, although they possess a monoderm cell wall architecture. The strain grew at 37 degrees C within a pH range of 5 to 8 and produced short-, branched-, and medium-chain carboxylates as well as ammonium, H2 and CO2, with acetate and propanoate produced or consumed depending on fermentation conditions. The genome consists of a single 2.4 Mbp chromosome with a G+C content of 50.2% and 2,131 predicted genes. Phylogenetic analysis of the 16S rRNA gene against other isolates revealed that strain F2T is most similar to Eubacterium pyruvativorans I-6T (92.06% 16S rRNA identity). Based on further phenotypic, genomic, and phylogenetic analysis, strain F2T represents a novel genus and species within the family Anaerovoracaceae with the proposed name Peptonella octanoica gen. nov. sp. nov. The type strain is F2T (strain accession pending). As a member of this same genus-level clade, we propose reclassifying Eubacterium pyruvativorans as Peptonella pyruvativorans comb. nov. These findings disambiguate Peptonella spp. from the phylogenetically distant and phenotypically distinct Eubacterium limosum ATCC 8486T.

Two thermophilic bacterial strains, designated OKO1 and KUI1, were isolated from hot springs within the Taup[o] Volcanic Zone of New Zealand. Analysis of the 16S rRNA gene identified both as members of the genus Venenivibrio, sharing 99.13% and 98.82% sequence similarity with Venenivibrio stagnispumantis CP.B2T, respectively. The novel isolates were characterised using a polyphasic taxonomic approach alongside V. stagnispumantis. Despite their close phylogenetic relationship, the strains differed markedly in cell morphology, physiology and genomic content. Both isolates exhibited broad tolerance to temperature and pH, while re-examination V. stagnispumantis CP.B2T revealed substantially wider physiological capabilities than previously reported, bringing its phenotype into closer agreement with the new isolates. Comparative genomic analyses identified key differences in genes encoding cytochromes, hydrogenases, and nitrogen metabolism, suggesting distinct metabolic potential among the strains. Although the genomes shared average nucleotide identity (ANI) values of 95-96%, placing them near the accepted species boundary, the combined phenotypic and genomic evidence support recognition of OKO1T and KUI1T as two species within the genus. We therefore propose Venenivibrio orakeikorakoensis sp. nov. (type strain OKO1T, ACCESSION) and Venenivibrio aotearoaensis sp. nov. (type strain KUI1T, ACCESSION) as new members within the genus, and emend the descriptions of Venenivibrio stagnispumantis and the genus Venenivibrio to incorporate the expanded phenotypic and genomic diversity revealed in this study.