Paucibacter sediminis sp. nov., isolated from sediment in a freshwater pond.

A Gram-stain-negative, aerobic, oxidase-positive, weakly catalase-positive, motile by means of a single polar flagellum, rod-shaped bacterium designated as strain S2-9T was isolated from sediment sampled in Wiyang pond, Republic of Korea. Growth of this strain was observed at 10-40 °C (optimum, 35 °C) and pH 5.5-9.5 (optimum, pH 7.0-8.0) and in the presence of 0-0.5 % NaCl in Reasoner's 2A broth. The major fatty acids (>10 %) of strain S2-9T were C16 : 0 and summed feature 3 (comprising a mixture of C16 : 1 ω7c and/or C16 : 1 ω6c). Ubiquinone-8 was detected as the respiratory quinone. The major polar lipids were phosphatidylethanolamine and phosphatidylglycerol. Strain S2-9T showed the highest 16S rRNA gene sequence similarity to Paucibacter oligotrophus CHU3T (98.7 %), followed by 'Paucibacter aquatile' CR182 (98.4 %), all type strains of Pelomonas species (98.1-98.3 %), Mitsuaria chitosanitabida NBRC 102408T (97.9 %), Kinneretia asaccharophila KIN192T (97.8 %), Mitsuaria chitinivorans HWN-4T (97.4 %), and Paucibacter toxinivorans 2C20T (97.4 %). Phylogenetic trees based on the 16S rRNA gene and whole-genome sequences showed that strain S2-9T formed a tight phylogenetic lineage with Paucibacter species (CHU3T, CR182, and 2C20T). Average nucleotide identity and digital DNA-DNA hybridization values between strain S2-9T and Paucibacter strains were 76.6-79.3% and 19.5-21.5 %, respectively. The genomic DNA G+C content of strain S2-9T was 68.3 mol%. Notably, genes responsible for both sulphur oxidation and reduction and denitrification were found in the genome of strain S2-9T, suggesting that strain S2-9T is involved in the nitrogen and sulphur cycles in pond ecosystems. Based on the polyphasic taxonomic results, strain S2-9T represents a novel species of the genus Paucibacter, for which the name Paucibacter sediminis sp. nov. is proposed. The type strain is S2-9T (= KACC 22267T= JCM 34541T).

Bifidobacterium apis sp. nov., isolated from the gut of honeybee (Apis mellifera).

A novel bifidobacterium (designated F753-1T) was isolated from the gut of honeybee (Apis mellifera). Strain F753-1T was characterized using a polyphasic taxonomic approach. Strain F753-1T was phylogenetically related to the type strains of Bifidobacterium mizhiensis, Bifidobacterium asteroides, Bifidobacterium choladohabitans, Bifidobacterium mellis, Bifidobacterium apousia and Bifidobacterium polysaccharolyticum, having 98.4-99.8 % 16S rRNA gene sequence similarities. The phylogenomic tree indicated that strain F753-1T was most closely related to the type strains of B. mellis and B. choladohabitans. Strain F753-1T had the highest average nucleotide identity (94.1-94.5 %) and digital DNA-DNA hybridization (56.3 %) values with B. mellis Bin7NT. Acid production from amygdalin, d-fructose, gentiobiose, d-mannose, maltose, sucrose and d-xylose, activity of α-galactosidase, pyruvate utilization and hydrolysis of hippurate could differentiate strain F753-1T from B. mellis CCUG 66113T and B. choladohabitans JCM 34586T. Based upon the data obtained in the present study, a novel species, Bifidobacterium apis sp. nov., is proposed, and the type strain is F753-1T (=CCTCC AB 2023227T=JCM 36562T=LMG 33388T).

Geographical and climatic distribution of lentil-nodulating rhizobia in Iran.

Lentil is one of the most important legumes cultivated in various provinces of Iran. However, there is limited information about the symbiotic rhizobia of lentils in this country. In this study, molecular identification of lentil-nodulating rhizobia was performed based on 16S-23S rRNA intergenic spacer (IGS) and recA, atpD, glnII, and nodC gene sequencing. Using PCR-RFLP analysis of 16S-23S rRNA IGS, a total of 116 rhizobia isolates were classified into 20 groups, leaving seven strains unclustered. Phylogenetic analysis of representative isolates revealed that the rhizobia strains belonged to Rhizobium leguminosarum and Rhizobium laguerreae, and the distribution of the species is partially related to geographical location. Rhizobium leguminosarum was the dominant species in North Khorasan and Zanjan, while R. laguerreae prevailed in Ardabil and East Azerbaijan. The distribution of the species was also influenced by agroecological climates; R. leguminosarum thrived in cold semiarid climates, whereas R. laguerreae adapted to humid continental climates. Both species exhibited equal dominance in the Mediterranean climate, characterized by warm, dry summers and mild, wet winters, in Lorestan and Kohgiluyeh-Boyer Ahmad provinces.

Chromosome organization shapes replisome dynamics in Caulobacter crescentus.

DNA replication in bacteria takes place on highly compacted chromosomes, where segregation, transcription, and repair must occur simultaneously. Within this dynamic environment, colocalization of sister replisomes has been observed in many bacterial species, driving the hypothesis that a physical linker may tether them together. However, replisome splitting has also been reported in many of the same species, leaving the principles behind replisome organization a long-standing puzzle. Here, by tracking the replisome ß-clamp subunit in live Caulobacter crescentus, we find that rapid DNA segregation can give rise to a second focus which resembles a replisome, but does not replicate DNA. Sister replisomes can remain colocalized, or split apart to travel along DNA separately upon disruption of chromosome inter-arm alignment. Furthermore, chromosome arm-specific replication-transcription conflicts differentially modify replication speed on the two arms, facilitate the decoupling of the two replisomes. With these observations, we conclude that the dynamic chromosome organization flexibly shapes the organization of sister replisomes, and we outline principles which can help to reconcile previously conflicting models of replisome architecture.

Oral-to-rectum microbial transmission in orthopedic patients without a history of intestinal disorders.

The enrichment of oral taxa in the gut has recently been reported as a notable alteration in the microbial balance in patients with intestinal disorders. However, translocation in populations without such diseases remains controversial. In this study, we examined 49 pairs of tongue and rectal samples collected from orthopedic patients without a history of intestinal disorders to verify the presence of oral taxa in the rectal microbiota. The bacterial composition of each sample was determined using 16S rRNA gene sequencing and amplicon sequence variant (ASV) analysis. Although the bacterial compositions of the tongue and rectal microbiota were distinctly different, tongue ASVs were detected in 67.3% of the participants and accounted for 0.0%-9.37% of the rectal microbiota. Particularly, Streptococcus salivarius, Fusobacterium nucleatum, and Streptococcus parasanguinis were abundant in the rectal microbiota. According to the network analysis, tongue taxa, such as S. salivarius and S. parasanguinis, formed a cohabiting group with Klebsiella pneumoniae and Alistipes finegoldii in the rectal microbiota. The total abundance of tongue ASVs in the rectal microbiota was significantly higher in participants with older age, hypertension, and proton pump inhibitor (PPI) use. Our study presents an extensive translocation of oral taxa to the rectum of a population without intestinal disorders and suggests that aging, hypertension, and PPI use are associated with an increased abundance of oral taxa and potential pathogenic bacteria in the rectal microbiota.

Microbiological exploration of the Cueva del Viento lava tube system in Tenerife, Canary Islands.

Cueva del Viento, located in the Canary Islands, Spain, is the Earth's sixth-longest lava tube, spanning 18,500 m, and was formed approximately 27,000 years ago. This complex volcanic cave system is characterized by a unique geomorphology, featuring an intricate network of galleries. Despite its geological significance, the geomicrobiology of Cueva del Viento remains largely unexplored. This study employed a combination of culture-dependent techniques and metabarcoding data analysis to gain a comprehensive understanding of the cave's microbial diversity. The 16S rRNA gene metabarcoding approach revealed that the coloured microbial mats (yellow, red and white) coating the cave walls are dominated by the phyla Actinomycetota, Pseudomonadota and Acidobacteriota. Of particular interest is the high relative abundance of the genus Crossiella, which is involved in urease-mediated biomineralization processes, along with the presence of genera associated with nitrogen cycling, such as Nitrospira. Culture-dependent techniques provided insights into the morphological characteristics of the isolated species and their potential metabolic activities, particularly for the strains Streptomyces spp., Paenarthrobacter sp. and Pseudomonas spp. Our findings underscore the potential of Cueva del Viento as an ideal environment for studying microbial diversity and for the isolation and characterization of novel bacterial species of biotechnological interest.

Paraburkholderia translucens sp. nov. and Paraburkholderia sejongensis sp. nov., isolated from grassland soil and showing plant growth promoting potential.

Two Gram-negative bacterial strains designated MMS20-SJTN17T and MMS20-SJTR3T were isolated from a grassland soil sample, and taxonomically characterized using a polyphasic approach. The 16S rRNA gene sequence analysis indicates that both strains belong to the genus Paraburkholderia of the class Betaproteobacteria, with strain MMS20-SJTN17T being mostly related to Paraburkholderia sprentiae WSM5005T (96.45 % sequence similarity) and strain MMS20-SJTR3T to Paraburkholderia tuberum STM678T (98.59 % sequence similarity). MMS20-SJTN17T could grow at 15-40 °C (optimum, 25-30 °C) and at pH 6.0-8.0 (optimum, pH 6.0-7.0), whereas MMS20-SJTR3T could grow at 10-40 °C (optimum, 30-37 °C) and at pH 6.0-8.0 (optimum, pH 6.0). Both strains tolerated up to 1 % (w/v) NaCl (optimum, 0 %). The major fatty acids of MMS20-SJTN17T were C16 : 0 and C19 : 0 cyclo ω8c, and those of MMS20-SJTR3T were C17 : 0 cyclo and a summed feature comprising C18 : 1 ω7c and/or C18 : 1 ω6c. The major isoprenoid quinone of both strains was ubiquinone-8 and the diagnostic polar lipids were diphosphatidylglycerol, phosphatidylglycerol and phosphatidylethanolamine. Regarding plant growth promoting potential, both strains were capable of producing indole acetic acid, siderophore and 1-aminocyclopropane-1-carboxylic acid deaminase, and also showed phosphate-solubilizing activity. A genome-based comparison using orthologous average nucleotide identity and digital DNA-DNA hybridization values indicates that strain MMS20-SJTN17T shares highest relatedness with Paraburkholderia monticola JC2948T and MMS20-SJTR3T with Paraburkholderia antibiotica G-4-1-8T, with values clearly below the cutoffs for species distinction. Examination of biosynthetic gene clusters responsible for secondary metabolite production reveals unique characteristics distinguishing each strain from closely related Paraburkholderia species. On the basis of genotypic, phenotypic, chemotaxonomic and phylogenomic data, each strain should be classified as a novel species of the genus Paraburkholderia, for which the names Paraburkholderia translucens sp. nov. (=MMS20-SJTN17T=LMG 32366T=KCTC 82783T) and Paraburkholderia sejongensis sp. nov. (=MMS20-SJTR3T=LMG 32367T=KCTC 82784T) are proposed.

Ruixingdingia sedimenti gen. nov., sp. nov., a novel taxon within the family Paracoccaceae isolated from sediment of Qiantang River.

A Gram-stain-negative bacterium, designated LG-4T, was isolated from sediment of Qiantang River in Zhejiang Province, PR China. Cells were strictly aerobic, non-spore-forming, non-motile and short-rod-shaped (1.0-1.2 µm long and 0.7-0.8 µm wide). Growth occurred at 15-42 °C (optimum, 30 °C), at pH 5.0-9.0 (pH 7.0) and at 0-2.0 % (w/v) NaCl (optimum, 0.5 % NaCl). Strain LG-4T showed 95.75-96.90 % 16S rRNA gene sequence similarity to various type strains of the genera Tabrizicola, Pseudotabrizicola, Phaeovulum, Rhodobacter and Wagnerdoeblera of the family Paracoccaceae, and the most closely related strain was Tabrizicola soli ZQBWT (96.90 % similarity). The phylogenomic tree showed that strain LG-4T clustered in the family Paracoccaceae and was positioned outside of the clade composed of the genera Wagnerdoeblera and Falsigemmobacter. The average nucleotide identity and digital DNA-DNA hybridization values between strain LG-4T and the related type strains were in the range of 74.19-77.56 % and 16.70-25.80 %, respectively. The average amino acid identity (AAI) values between strain LG-4T and related type strains of the family Paracoccaceae were 60.94-69.73 %, which are below the genus boundary (70 %). The evolutionary distance (ED) values between LG-4T and the related genera of the family Paracoccaceae were 0.21-0.34, which are within the recommended standard (≥0.21-0.23) for defining a novel genus in the family Paracoccaceae. The predominant cellular fatty acids were C18 : 1 ω7c, C19 : 0 cyclo ω8c, C18 : 0 and C16 : 0, the isoprenoid quinone was Q-10, and the major polar lipids were phospholipid, phosphatidylglycerol, phosphatidylcholine, aminolipid and two unknown polar lipids. The genome size was 4.7 Mb with 68.6 mol% G+C content. On the basis of distinct phylogenetic relationships, low AAI values and high ED values, and differential phenotypic, physiological and biochemical characteristics, strain LG-4T represents a novel species of a new genus in the family Paracoccaceae, for which the name Ruixingdingia sedimenti gen. nov., sp. nov. is proposed. The type strain is LG-4T (=MCCC 1K08849T=KCTC 8136T).

Ferriphaselus amnicola strain GF-20, a new iron- and thiosulfate-oxidizing bacterium isolated from a hard rock aquifer.

Ferriphaselus amnicola GF-20 is the first Fe-oxidizing bacterium isolated from the continental subsurface. It was isolated from groundwater circulating at 20 m depth in the fractured-rock catchment observatory of Guidel-Ploemeur (France). Strain GF-20 is a neutrophilic, iron- and thiosulfate-oxidizer and grows autotrophically. The strain shows a preference for low oxygen concentrations, which suggests an adaptation to the limiting oxygen conditions of the subsurface. It produces extracellular stalks and dreads when grown with Fe(II) but does not secrete any structure when grown with thiosulfate. Phylogenetic analyses and genome comparisons revealed that strain GF-20 is affiliated with the species F. amnicola and is strikingly similar to F. amnicola strain OYT1, which was isolated from a groundwater seep in Japan. Based on the phenotypic and phylogenetic characteristics, we propose that GF-20 represents a new strain within the species F. amnicola.

Chelativorans salis sp. nov., a slightly halophilic bacterium isolated from an enrichment system with saline lake sediment.

A Gram-stain-negative, non-motile, and slightly halophilic alphaproteobacterium, designated strain EGI FJ00035T, was isolated from enrichment sediment samples of a saline lake in Xinjiang Uygur Autonomous Region, PR China. The taxonomic position of the isolate was determined using the polyphasic taxonomic and phylogenomic analyses. Phylogenetic analysis based on the 16S rRNA gene sequences indicated that strain EGI FJ00035T formed a distinct clade with 'Chelativorans alearense' UJN715 and 'Chelativorans xinjiangense' lm93 with sequence similarities of 98.44 and 98.22 %, respectively, while sharing less than 96.7 % with other valid type strains. The novel isolate could be distinguished from other species of the genus Chelativorans by its distinct phenotypic, physiological, and genotypic characteristics. Optimal growth of strain EGI FJ00035T occurred on marine agar 2216 at pH 7.0 and 30 °C. The major respiratory quinone was Q-10, while the major fatty acids (>5 %) were C19 : 0 cyclo ω8c, summed feature 8 (C17 : 1 ω6c and/or C17 : 1 ω7c), C16 : 0, C18 : 0, and iso-C17 : 0. The detected polar lipids included diphosphatidylglycerol, phosphatidylcholine, phosphatidylethanolamine, phosphatidylglycerol, unidentified aminophospholipids, unidentified glycolipids, and an unidentified lipid. Based on its genome sequence, the G+C content of strain EGI FJ00035T was 63.2 mol%. The average nucleotide identity, average amino acid identity, and digital DNA-DNA hybridization values of strain EGI FJ00035T against related members of the genus Chelativorans were below the thresholds for delineation of a novel species. According our polyphasic taxonomic data, strain EGI FJ00035T represents a new species of the genus Chelativorans, for which the name Chelativorans salis sp. nov. is proposed. The type strain of the proposed novel isolate is EGI FJ00035T (=KCTC 92251T=CGMCC 1.19480T).

Massilia luteola sp. nov., a novel indole-producing and cellulose-degrading bacterium isolated from soil.

A Gram-stain-negative, rod-shaped, indole-producing, and cellulose-degrading bacterial strain, designated NEAU-G-C5T, was isolated from soil collected from a forest in Dali city, Yunnan province, south China. 16S rRNA gene sequence analysis showed that strain NEAU-G-C5T was assigned to the genus Massilia and showed high sequence similarities to Massilia phosphatilytica 12-OD1T (98.32 %) and Massilia putida 6 NM-7T (98.41 %). Phylogenetic analysis based on 16S rRNA gene sequences indicated that strain NEAU-G-C5T formed a lineage related to M. phosphatilytica 12-OD1T and M. putida 6 NM-7T. The major fatty acids of the strain were C16 : 0, C16 : 1 ω7c, and C17 : 0 cyclo. The respiratory quinone was Q-8. The polar lipid profile of the strain showed the presence of diphosphatidylglycerol, phosphatidylglycerol, and phosphatidylethanolamine. In addition, the average nucleotide identity values between strain NEAU-G-C5T and its reference strains M. phosphatilytica 12-OD1T, M. putida 6 NM-7T, M. norwichensis NS9T, and M. kyonggiensis TSA1T were 89.7, 88.2, 81.3, and 88.0 %, respectively, and the levels of digital DNA-DNA hybridization between them were found to be 58.5 % (54.9-62.0 %), 53.2 % (49.8-56.7 %), 31.9 % (28.6-35.5 %), and 57.7 % (54.1-61.2 %), respectively, which were lower than the accepted threshold values of 95-96 % and 70 %, respectively. The DNA G+C content of strain NEAU-G-C5T was 66.5 mol%. The strain could produce indoleacetic acid and cellulase. On the basis of the phenotypic, genotypic, and chemotaxonomic characteristics, we conclude that strain NEAU-G-C5T represents a novel species of the genus Massilia, for which the name Massilia luteola sp. nov. is proposed. The type strain is NEAU-G-C5T (=MCCC 1K08668T=KCTC 8080T).

Genome-based reclassification of Salipiger manganoxidans (Rajasabapathy et al. 2016) Wirth et al. 2018 as a later heterotypic synonym of Salipiger marinus (Lai et al. 2011) Wirth et al. 2018.

Salipiger manganoxidans VSW210T was compared with Salipiger marinus CK-I3-6T to examine the taxonomic relationship between the two type strains. In phylogenetic trees drawn using whole genome sequences and 16S rRNA gene sequences, S. manganoxidans VSW210T and S. marinus CK-I3-6T clade together and showed a 99.6 % 16S rRNA sequence similarity. The average amino acid identity (AAI), average nucleotide identity (ANIb and ANIm) and digital DNA-DNA hybridization (dDDH) values between S. manganoxidans VSW210T and S. marinus CK-I3-6T were below 97.5, 97.4, 98.4 and 85.1±2.5 %, respectively, all of which were greater than the species delineation threshold AAI value (95.5 %), ANI value (95-96 %) and dDDH value (70 %). Most phenotypic features between both species were almost identical, although there were some differences. The present results show that Salipiger manganoxidans is a later heterotypic synonym of Salipiger marinus.

Achromobacter seleniivolatilans sp. nov. and Buttiauxella selenatireducens sp. nov., isolated from the rhizosphere of selenium hyperaccumulator Cardamine hupingshanesis.

Two Gram-stain-negative bacterial strains, R39T and R73T, were isolated from the rhizosphere soil of the selenium hyperaccumulator Cardamine hupingshanesis in China. Strain R39T transformed selenite into elemental and volatile selenium, whereas strain R73T transformed both selenate and selenite into elemental selenium. Phylogenetic and phylogenomic analyses indicated that strain R39T belonged to the genus Achromobacter, while strain R73T belonged to the genus Buttiauxella. Strain R39T (genome size, 6.68 Mb; G+C content, 61.6 mol%) showed the closest relationship to Achromobacter marplatensis LMG 26219T and Achromobacter kerstersii LMG 3441T, with average nucleotide identity (ANI) values of 83.6 and 83.4 %, respectively. Strain R73T (genome size, 5.22 Mb; G+C content, 50.3 mol%) was most closely related to Buttiauxella ferragutiae ATCC 51602T with an ANI value of 86.4 %. Furthermore, strain A111 from the GenBank database was found to cluster with strain R73T within the genus Buttiauxella through phylogenomic analyses. The ANI and digital DNA-DNA hybridization values between strains R73T and A111 were 97.5 and 80.0% respectively, indicating that they belong to the same species. Phenotypic characteristics also differentiated strain R39T and strain R73T from their closely related species. Based on the polyphasic analyses, strain R39T and strain R73T represent novel species of the genera Achromobacter and Buttiauxella, respectively, for which the names Achromobacter seleniivolatilans sp. nov. (type strain R39T=GDMCC 1.3843T=JCM 36009T) and Buttiauxella selenatireducens sp. nov. (type strain R73T=GDMCC 1.3636T=JCM 35850T) are proposed.

Refining the taxonomy of the order Hyphomicrobiales (Rhizobiales) based on whole genome comparisons of over 130 type strains.

The alphaproteobacterial order Hyphomicrobiales consists of 38 families comprising at least 152 validly published genera as of January 2024. The order Hyphomicrobiales was first described in 1957 and underwent important revisions in 2020. However, we show that several inconsistencies in the taxonomy of this order remain and we argue that 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.

Pectobacterium araliae sp. nov., a pathogen causing bacterial soft rot of Japanese angelica tree in Japan.

Phytopathogenic bacteria (MAFF 302110T and MAFF 302107) were isolated from lesions on Japanese angelica trees affected by bacterial soft rot in Yamanashi Prefecture, Japan. The strains were Gram-reaction-negative, facultatively anaerobic, motile with peritrichous flagella, rod-shaped, and non-spore-forming. The genomic DNA G+C content was 51.1 mol % and the predominant cellular fatty acids included summed feature 3 (C16 : 1 ω7c and/or C16 : 1 ω6c), C16 : 0, summed feature 8 (C18 : 1 ω7c and/or C18 : 1 ω6c), summed feature 2 (comprising any combination of C12 : 0 aldehyde, an unknown fatty acid with an equivalent chain length of 10.928, C16 : 1 iso I, and C14 : 0 3OH), and C12 : 0. Phylogenetic analyses based on 16S rRNA and gyrB gene sequences, along with phylogenomic analysis utilizing whole-genome sequences, consistently placed these strains within the genus Pectobacterium. However, their phylogenetic positions did not align with any known species within the genus. Comparative studies involving average nucleotide identity and digital DNA-DNA hybridization with the closely related species indicated values below the thresholds employed for the prokaryotic species delineation (95-96 % and 70 %, respectively), with the highest values observed for Pectobacterium polonicum DPMP315T (92.10 and 47.1 %, respectively). Phenotypic characteristics, cellular fatty acid composition, and a repertoire of secretion systems could differentiate the strains from their closest relatives. The phenotypic, chemotaxonomic, and genotypic data obtained in this study show that MAFF 302110T/MAFF 302107 represent a novel species of the genus Pectobacterium, for which we propose the name Pectobacterium araliae sp. nov., designating MAFF 302110T (=ICMP 25161T) as the type strain.

Microbaculum marinisediminis sp. nov., isolated from marine sediment.

A novel Gram-stain-negative and facultatively anaerobic bacterium, designated A6E488T, was isolated from intertidal sediment collected from Xiaoshi Island, Weihai, PR China (122° 1' E 37° 31' N). Cells of strain A6E488T were rod-shaped with widths of 0.3-0.4 µm and lengths of 1.1-1.8 µm. The optimal growth conditions were determined to be in 1 % (w/v) NaCl, at 37 °C, and at pH 7.0. The predominant fatty acids (≥10 %) were C19 : 0 cyclo ω8c (59.7 %) and summed feature 8 (13.8 %, C18 : 1 ω7c and/or C18 : 1 ω6c). The sole isoprenoid quinone was Q-10. Oxidase activity was negative but catalase activity was positive. The polar lipids consisted of diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine, one unidentified phospholipid, one unidentified aminolipid, one unidentified glycolipid, and one unidentified lipid. Based on phylogenetic analysis of 16S rRNA gene sequences, strain A6E488T showed the highest sequence similarity to Microbaculum marinum MCCC 1K03192T (97.6 %). The average nucleotide identity (ANI) and digital DNA-DNA hybridization (dDDH) values between strain A6E488T and M. marinum MCCC 1K03192T did not exceed 78 and 22 %, respectively. These values are below the recommended thresholds of 95 % (ANI) and 70 % (dDDH) for prokaryotic species delineation. On the basis of gene annotation, it was observed that strain A6E488T possesses the capability for thiosulphate oxidation, suggesting that this strain might be important in the sulphur cycle. Based on the results of phenotypic, genotypic, and chemical characterization, strain A6E488T is considered to represent a novel species of the genus Microbaculum, for which the name Microbaculum marinisediminis sp. nov. is proposed. The type strain is A6E488T (=KCTC 92197T=MCCC 1H00516T).

Saccharopolyspora ipomoeae sp. nov., an Actinomycete Isolated from Sweet Potato Field Soils.

During the course of the isolation of actinobacteria from sweet potato field soils collected from Phra Nakhon Si Ayutthaya province of Thailand, strain TS4A08T was isolated and subjected to a polyphasic taxonomic approach. The 16S rRNA gene sequence analysis of strain TS4A08T revealed that it is closely related to the type strains of Saccharopolyspora aridisoli, and Saccharopolyspora endophytica with 98.7%, and 98.6% similarity, respectively. However, phylogenetic analyses using 16S rRNA gene and genome sequences indicated that strain TS4A08T clustered with Saccharopolyspora flava AS4.1520T (98.2% similarity), well-supported by bootstrap values, and formed distinct line from the two closest strains. The average nucleotide identity (ANI) values and digital DNA-DNA hybridization (dDDH) values between the genome sequences of strain TS4A08T and the closest type strains of S. aridisoli, S. endophytica, and S. flava, were 86.1-93.2% and 33.1-49.6%, respectively, which were less than the threshold for the species delineation. The genome size and the DNA G + C content of strain TS4A08T were 6.6 Mbp and 70.5%, respectively. The strain grew well at 25-37 °C, pH range of 7-9, and NaCl concentration of 0-5% (w/v). Whole-cell hydrolysates contained meso-diaminopimelic acid. The major fatty acids were iso-C16:0, anteiso-C17:0, and iso-C15:0. Strain TS4A08T exhibited phosphatidylcholine in its polar lipid profile, with MK-9(H4) being the predominant isoprenologue. The strain exhibits typical chemotaxonomic properties of the genus Saccharopolyspora, including arabinose, galactose, and ribose as whole-cell sugars. Strain TS4A08T represents a novel species within the genus Saccharopolyspora, for which the name Saccharopolyspora ipomoeae sp. nov. is proposed. The type strain is TS4A08T (= TBRC 17271T = NBRC 115967T).

Zoothamnium mariella sp. nov., a marine, colonial ciliate with an atypcial growth pattern, and its ectosymbiont Candidatus Fusimicrobium zoothamnicola gen. nov., sp. nov.

Ciliates are unicellular eukaryotes, regularly involved in symbiotic associations. Symbionts may colonize the inside of their cells as well as their surface as ectosymbionts. Here, we report on a new ciliate species, designated as Zoothamnium mariella sp. nov. (Peritrichia, Sessilida), discovered in the northern Adriatic Sea (Mediterranean Sea) in 2021. We found this ciliate species to be monospecifically associated with a new genus of ectosymbiotic bacteria, here proposed as Candidatus Fusimicrobium zoothamnicola gen. nov., sp. nov. To formally describe the new ciliate species, we investigated its morphology and sequenced its 18S rRNA gene. To demonstrate its association with a single species of bacterial ectosymbiont, we performed 16S rRNA gene sequencing, fluorescence in situ hybridization, and scanning electron microscopy. Additionally, we explored the two partners' cultivation requirements and ecology. Z. mariella sp. nov. was characterized by a colony length of up to 1 mm. A consistent number of either seven or eight long branches alternated on the stalk in close distance to each other. The colony developed three different types of zooids: microzooids ("trophic stage"), macrozooids ("telotroch stage"), and terminal zooids ("dividing stage"). Viewed from inside the cell, the microzooids' oral ciliature ran in 1 » turns in a clockwise direction around the peristomial disc before entering the infundibulum, where it performed another ¾ turn. Phylogenetic analyses assigned Z. mariella sp. nov. to clade II of the family Zoothamnidae. The ectosymbiont formed a monophyletic clade within the Gammaproteobacteria along with two other ectosymbionts of peritrichous ciliates and a free-living vent bacterium. It colonized the entire surface of its ciliate host, except for the most basal stalk of large colonies, and exhibited a single, spindle-shaped morphotype. Furthermore, the two partners together appear to be generalists of temperate, oxic, marine shallow-water environments and were collectively cultivable in steady flow-through systems.

Flavobacterium psychraquaticum sp. nov., isolated from water system of Atlantic salmon (Salmo salar) smolts cultured in Chile.

Strain LB-N7T, a novel Gram-negative, orange, translucent, gliding, rod-shaped bacterium, was isolated from water samples collected from an open system of Atlantic salmon (Salmo salar) smolts in a fish farm in Chile during a flavobacterial infection outbreak in 2015. Phylogenetic analysis based on 16S rRNA sequences (1337 bp) revealed that strain LB-N7T belongs to the genus Flavobacterium and is closely related to the type strains Flavobacterium ardleyense A2-1T (98.8 %) and Flavobacterium cucumis R2A45-3T (96.75 %). The genome size of strain LB-N7T was 2.93 Mb with a DNA G+C content 32.6 mol%. Genome comparisons grouped strain LB-N7T with Flavobacterium cheniae NJ-26T, Flavobacterium odoriferum HXWNR29T, Flavobacterium lacisediminis TH16-21T and Flavobacterium celericrescens TWA-26T. The calculated digital DNA-DNA hybridization values between strain LB-N7T and the closest related Flavobacterium strains were 23.3 % and the average nucleotide identity values ranged from 71.52 to 79.39 %. Menaquinone MK-6 was the predominant respiratory quinone, followed by MK-7. The major fatty acids were iso-C15 : 0 and anteiso-C15 : 0. The primary polar lipids detected included nine unidentified lipids, two amounts of aminopospholipid and phospholipids, and a smaller amount of aminolipid. Phenotypic, genomic, and chemotaxonomic data suggest that strain LB-N7T (=CECT 30406T=RGM 3221T) represents as a novel bacterial species, for which the name Flavobacterium psychraquaticum sp. nov. is proposed.