A distinct Fusobacterium nucleatum clade dominates the colorectal cancer niche.

Fusobacterium nucleatum (Fn), a bacterium present in the human oral cavity and rarely found in the lower gastrointestinal tract of healthy individuals1, is enriched in human colorectal cancer (CRC) tumours2-5. High intratumoural Fn loads are associated with recurrence, metastases and poorer patient prognosis5-8. Here, to delineate Fn genetic factors facilitating tumour colonization, we generated closed genomes for 135 Fn strains; 80 oral strains from individuals without cancer and 55 unique cancer strains cultured from tumours from 51 patients with CRC. Pangenomic analyses identified 483 CRC-enriched genetic factors. Tumour-isolated strains predominantly belong to Fn subspecies animalis (Fna). However, genomic analyses reveal that Fna, considered a single subspecies, is instead composed of two distinct clades (Fna C1 and Fna C2). Of these, only Fna C2 dominates the CRC tumour niche. Inter-Fna analyses identified 195 Fna C2-associated genetic factors consistent with increased metabolic potential and colonization of the gastrointestinal tract. In support of this, Fna C2-treated mice had an increased number of intestinal adenomas and altered metabolites. Microbiome analysis of human tumour tissue from 116 patients with CRC demonstrated Fna C2 enrichment. Comparison of 62 paired specimens showed that only Fna C2 is tumour enriched compared to normal adjacent tissue. This was further supported by metagenomic analysis of stool samples from 627 patients with CRC and 619 healthy individuals. Collectively, our results identify the Fna clade bifurcation, show that specifically Fna C2 drives the reported Fn enrichment in human CRC and reveal the genetic underpinnings of pathoadaptation of Fna C2 to the CRC niche.

Description of an anaerobic actinobacterium, Kribbibacterium absianum gen. nov., sp. nov., a new member of the novel family Kribbibacteriaceae fam. nov., and reclassification of the genera Granulimonas and Leptogranulimonas.

Two rod-shaped, obligate anaerobic, Gram-stain-positive bacteria isolated from the pig faeces were designated YH-ols2216 and YH-ols2217T. Analysis of 16S rRNA gene sequences revealed that these isolates were most related to the members of the family Atopobiaceae, within the order Coriobacteriales, and Granulimonas faecalis KCTC 25474T with 92.0 and 92.5% similarities, respectively. The 16S rRNA gene sequence similarity within isolates was 99.9 %; and those between isolates YH-ols2216 and YH-ols2217T, and Atopobium minutum DSM 20586T, the type species of the type genus Atopobium within the family Atopobiaceae, were 88.5 and 88.7 %, respectively. Those between isolates and Coriobacterium glomerans PW2T, the type species of the type genus Coriobacterium within the family Coriobacteriaceae, were 88.7 and 89.1 %, respectively. The multi-locus sequence tree revealed that the isolates, alongside the genera Granulimonas and Leptogranulimonas, formed a distinct cluster between the families Atopobiaceae and Coriobacteriaceae. The average nucleotide identities and digital DNA-DNA hybridization values for the isolates and their most closely related strains ranged from 67.7 to 76.2 % and from 18.4 to 23.3 %, respectively. The main cellular fatty acids of the isolates were C18 : 0 DMA, C18 : 1 ω9c, C18 : 0 12OH, C18 : 0, and C16 : 0. The cell wall contained the peptidoglycan meso-diaminopimelic acid. Lactate was the main end-product of the isolates. The major polar lipids of isolate YH-ols2217T were aminophospholipid, aminolipids, and lipids. Menaquinones were not identified in the cells of the isolates. The DNA G+C contents of isolates YH-ols2216 and YH-ols2217T were 67.5 and 67.6 mol%, respectively. Considering these chemotaxonomic, phenotypic, and phylogenetic properties, Kribbibacteriaceae fam. nov. is proposed within the order Coriobacteriales. YH-ols2216 (=KCTC 25708=NBRC 116429) and YH-ols2217T (=KCTC 25709T=NBRC 116430T) represent a novel taxon within this new family and the name Kribbibacterium absianum gen. nov., sp. nov. is proposed. In addition, the genera Granulimonas and Leptogranulimonas are transferred to the family Kribbibacteriaceae fam. nov.

Aerococcus kribbianus sp. nov., a facultatively anaerobic bacterium isolated from pig faeces.

Two cocci-shaped, facultatively anaerobic, Gram-positive bacteria isolated from the faeces of a pig were designated as strains YH-aer221T and YH-aer222. Analysis of the 16S rRNA gene sequences revealed that the isolates were most closely related to Aerococcus suis JCM 18035T with 96.6 % similarity. The multi-locus sequence tree revealed that the isolates formed a sub-cluster adjacent to A. suis JCM 18035T. The average nucleotide identity values for the isolates and their most closely related strains were 71.8 and 71.7 %, respectively; and the digital DNA-DNA hybridization values for the isolates and their most closely related strains were 25.6 and 25.5 %, respectively. The main fatty acids were C18 : 1ω9c, C16 : 0 and C18 : 0. The cell wall contained the meso-diaminopimelic acid-based peptidoglycan. The two isolates shared the same metabolic pathways. Isolates YH-aer221T and YH-aer222 harboured the same CRISPR array with 33 and 46 spacers, respectively. Single-genome vs. metagenome analysis showed that the genomes of the isolates were not found in the available metagenome database. Given their chemotaxonomic, phenotypic and phylogenetic properties, YH-aer221T (= KCTC 25571T=JCM 35699T) and YH-aer222 (=KCTC 25573=JCM 35700) represent a novel taxon. The name Aerococcus kribbianus sp. nov. is proposed.

Lacticaseibacillus parakribbianus sp. nov., isolated from a pig farm faeces dump.

A lactic acid bacterium isolated from pig faeces was characterized using a polyphasic approach. The strain was Gram-stain-positive, rod-shaped, and facultative anaerobic. Phylogenetic analysis of the 16S rRNA gene sequence indicated that the isolate belonged to the genus Lacticaseibacillus. The multi-locus sequence tree revealed that the strain formed a sub-cluster adjacent to Lacticaseibacillus kribbianus. The main fatty acids were C16 : 0 and C18 : 1ω9c. The average nucleotide identity value, average amino acid identity, and genome-to-genome distance for YH-lacS6T and its most closely related strain, L. kribbianus, were 85.4, 85.2 and 29.2 %, respectively. The G+C content of the genomic DNA was 61.6 mol%. The major polar lipids were diphosphatidylglycerol, phosphatidylglycerol, aminophospholipids and phospholipids. The cell-wall peptidoglycan did not contain meso-diaminopimelic acid. Thus, YH-lacS6T (=KCTC 21186T=JCM 34954T) represents a novel species. The name Lacticaseibacillus parakribbianus sp. nov. is proposed.

Limosilactobacillus kribbianus sp. nov., isolated from pig faeces.

A rod-shaped, aerotolerant, Gram-stain-positive bacterium isolated from pig faeces was designated as strain YH-lim2214T. Analysis of the 16S rRNA gene sequence revealed that the isolate was most closely related to Limosilactobacillus pontis KCTC 25258T with 98.0 % similarity. The average nucleotide identity and average amino acid identity values between YH-lim2214T and the most closely related strain Lm. pontis KCTC 25258T were 81.4 and 81.3 %, respectively. The major fatty acids were C18 : 1 ω9c, summed feature 7 and C16 : 0. The cell-wall peptidoglycan type was A4α l-Lys-d-Asp. The genomic DNA G+C content was 51.1 mol%. The chemotaxonomic, phenotypic and phylogenetic properties of YH-lim2214T (=KCTC 25572T=JCM 35701T) suggest that it represents a novel taxon, for which the name Limosilactobacillus kribbianus sp. nov. is proposed.

Description and comparative genome analysis of Hallella absiana sp. nov., isolated from pig feces.

OBJECTIVE: The genus Hallella was described within Bacteroidaceae, and then reclassified within Prevotellaceae based on its phenotypic and phylogenetic description. It is associated with degradation of carbohydrate. However, some species of Hallella have pathobiotic properties, and are involved in infections and chronic inflammatory disorders. METHODS: Here, we used a polyphasic taxonomic approach to characterize the two strains: YH-C38T and YH-C4B9b. A detailed metabolic analysis was conducted to compare the two novel isolates with related strains within the genus Hallella. RESULT: Analysis of 16S rRNA gene sequences revealed that the isolates were most closely related to Hallella mizrahii JCM 34422T with 98.5% and 98.6% similarities, respectively. Analysis of the multi-locus species tree based on whole genome sequences of the isolates and related strains revealed that the isolates formed a sub-cluster adjacent to H. mizrahii JCM 34422T. The average nucleotide identity values for YH-C38T and YH-C4B9b, and the most closely related strain H. mizrahii JCM 34422T, were 93.5% and 93.8%, respectively. The main fatty acids were iso C17:0 3OH and anteiso C15:0. The predominant menaquinones were MK-12, MK-11, and MK-13. The cell wall contained the peptidoglycan of meso-diaminopimelic acid. Analysis of comparative metabolic analysis revealed that isolates YH-C38T and YH-C4B9b each contained 155 carbohydrate-active enzymes, and glycoside hydrolase was the largest family. CONCLUSION: Two rod-shaped, obligately anaerobic, Gram-stain-negative bacteria, isolated from pig feces, were designated as strains YH-C38T and YH-C4B9b. Based on the chemotaxonomic, phenotypic, and phylogenetic properties, YH-C38T (=KCTC 25103T = JCM 35423T) and YH-C4B9b (=KCTC 25104 = JCM 35609) represent a novel taxon. The name Hallella absiana sp. nov. is proposed.

Description of Fusibacillus kribbianus gen. nov., sp. nov., a fusiform anaerobe isolated from pig feces.

OBJECTIVE: The family Lachnospiraceae is affiliated with the order Clostridiales and was originally contained within Clostridial cluster XIVa. The members of Lachnospiraceae inhabiting the gut comprise the chemoorganotrophic genera, generating sundry short-chain fatty acids to supply energy to the host, and are considered to be related to obesity and gut health. METHODS: The polyphasic taxonomic approach was used to characterize the isolate YH-rum2234T. A detailed metabolic analysis was conducted to compare the novel isolate with related strains within the family Lachnospiraceae. RESULTS: A fusiform, obligately anaerobic, Gram-stain-negative bacterium, YH-rum2234T, was isolated from pig feces. Analysis of the 16S rRNA gene sequence revealed that the similarities between the isolate and the familiarly interrelated strain Lientehia hominis KCTC 25345T was 94.3%. The average nucleotide identities and genome-to-genome distances of YH-rum2234T and its closely related strains were below 85.5% and 32.5%, respectively. The G + C content of the genomic DNA was 49.2 mol%. The main fatty acids were C16:0, C14:0, and C14:0 DMA. The major polar lipids were aminophospholipids. The cell wall did not contain the peptidoglycan meso-diaminopimelic acid. CONCLUSION: Given the chemotaxonomic, phenotypic, and phylogenetic properties, YH-rum2234T (=KCTC 25710T = DSMZ 116041T) represents a new genus and species in the family Lachnospiraceae. Fusibacillus kribbianus gen. nov., sp. nov. is the proposed name.

Faecalicatena absiana sp. nov., an obligately anaerobic bacterium from a pig farm faeces dump.

An obligately anaerobic, Gram-stain-positive, spore-forming, short-rod-shaped bacterium, designated strain YH-C36aT, was isolated from a pig farm faeces dump. Phylogenetic analysis based on 16S rRNA gene sequences indicated that the isolate belongs to the genus Faecalicatena and is most closely related to Faecalicatena contorta KCTC 5831T, Faecalicatena fissicatena KCTC 15010T and Faecalicatena orotica KCTC 15331T, with 96.3, 96.2, and 96.0 % sequence similarity, respectively. The average nucleotide identity values for strain YH-C36aT and the closest related strains were lower than 72 %. The G+C content of the isolate was 43.0 mol%. The cell-wall peptidoglycan was A1γ type and contained meso-diaminopimelic acid. The predominant fatty acids were C16 : 0, C18 : 1 cis 9, C16 : 0 DMA, C18 : 0 DMA and C18:0. The major end products of glucose fermentation were lactate, formate and acetate. Based on its phenotypic, phylogenetic and chemotaxonomic properties, a novel species, named Faecalicatena absiana sp. nov., is proposed for strain YH-C36aT (=KCTC 25106T=NBRC 114768T).

Lacticaseibacillus kribbianus sp. nov., isolated from pig farm faeces dump.

A lactic acid bacteria isolated from pig faeces was characterized using a polyphasic approach. Cells of the strain were Gram-stain-positive, rod-shaped and facultative anaerobic. Phylogenetic analysis of 16S rRNA gene sequence indicated that the isolate belonged to the genus Lacticaseibacillus; however, the similarity to other homologues within the genus was <98 %. Analysis of housekeeping gene sequences (pheS and recA) revealed that the strain formed a sub-cluster adjacent to Lacticaseibacillus absianus and Lacticaseibacillus daqingensis. The main fatty acids of the strain is the C18 : 1ω9c and C16 : 0. The G+C content of the genomic DNA was 62.8 mol %. The major polar lipids were diphosphatidylglycerol, phosphatidylglycerol, aminophospholipids and phospholipids. The cell-wall peptidoglycan did not contain meso-diaminopimelic acid. Thus, YH-lac21T (=KCTC 21185=JCM 34953) represents a novel species. The name Lacticaseibacillus kribbianus sp. nov. is proposed.

Performance assessment of ASTA MicroIDSys, a new matrix assisted laser desorption ionization-time of flight mass spectrometry system, for identification of viridans group streptococci.

The performance of the ASTA MicroIDSys system (ASTA), a new matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS) system, was evaluated for the identification of viridans group streptococci (VGS) and compared with the results obtained with the Bruker Biotyper system (Bruker Daltonics). A total of 106 Streptococcus reference strains belonging to 24 species from the bacterial strain bank was analyzed using the two MALDI-TOF MS systems. Of the 106 reference strains tested, ASTA MicroIDSys and Bruker Biotyper correctly identified 84.9% and 81.1% at the species level, 100% and 97.2% at the group level and 100% and 98.1% at the genus level, respectively. The difference between the two systems was not statistically significant (P = 0.289). Out of 24 species, 13 species were accurately identified to the species level with 100% accurate identification rates with both systems. The accurate identification rates at the species level of ASTA MicroIDSys and Bruker Biotyper were 100% and 87.5% for the S. anginosus group; 78.4% and 73.5% for the S. mitis group; 91.7% and 91.7% for the S. mutans group; and 100% and 100% for the S. salivarius group, respectively. The ASTA MicroIDSys showed an identification performance equivalent to that of the Bruker Biotyper for VGS. Therefore, it would be useful for the identification of VGS strains in clinical microbiology laboratories.

Absicoccus porci gen. nov., sp. nov., a member of the family Erysipelotrichaceae isolated from pig faeces.

An obligately anaerobic, Gram-stain-positive and coccus-shaped bacterium, designated strain YH-panp20T, was isolated from pig faeces. Phylogenetic analysis based on 16S rRNA gene sequencing indicated that the isolate belongs to the family Erysipelotrichaceae, and is most closely related to Catenisphaera adipataccumulans KCTC 15517T (93.5 % sequence similarity), followed by Faecalitalea cylindroides KCTC 5815T (92.2 %), Faecalicoccus acidiformans KCTC 15521T (90.2 %) and Holdemanella biformis KCTC 5969T (89.6 %). Average nucleotide identity values between YH-panp20T and its closest relatives were lower than 71 %. The G+C content of the isolate was 38.4 mol%, and its cell-wall peptidoglycan was found to be of A1γ type and contained meso-diaminopimelic acid. The predominant fatty acids were C18 : 1 cis 9, C18 : 0 DMA and C16 : 0. The major end-products of glucose fermentation were lactate, acetate and formate. Therefore, based on the phenotypic, phylogenetic and chemotaxonomic properties, a novel genus and species, Absicoccus porci gen. nov., sp. nov., is proposed for isolate YH-panp20T (=KCTC 15747T=JCM 32769T).

Paenibacillus oralis sp. nov., Isolated from Human Subgingival Dental Plaque of Gingivitis Lesion.

A Gram-stain-negative, facultative anaerobic, spore-forming, motile, and rod-shaped bacterium, strain ChDC PVNT-B20T, was isolated from the human subgingival dental plaque of a gingivitis lesion. Phylogenetic analysis based on the 16S ribosomal RNA gene (16S rDNA) showed that the strain belonged to the genus Paenibacillus. BLAST analysis of 16S rDNA sequence of the strain displayed high identity to those of Paenibacillus faecis DSM 23593T (97.7% similarity) and Paenibacillus macerans ATCC 8244T (97.6% similarity). Draft genome of strain ChDC PVNT-B20T was composed of 8,112,407 bp. The DNA G+C content of the strain was 51.3 mol%. Average nucleotide identity values between strain ChDC PVNT-B20T and P. faecis DSM 23593T or P. macerans ATCC 8244T were 75.71% and 91.5%, respectively. Genome-to-genome distance values between strain ChDC PVNT-B20T and P. faecis DSM 23593T or P. macerans ATCC 8244T were 21.6% (19.3-24.0%) and 44.9% (42.3-47.4%), respectively. Major cellular fatty acids of strain ChDC PVNT-B20T were anteiso-C15:0 (43.4%), C16:0 (16.6%), iso-C16:0 (14.4%), and anteiso-C17:0 (12.4%). The sole respiratory quinone of the strain was menaqinone-7. Major polar lipids of the strain were phosphatidylglycerol (PG), diphosphatidylglycerol (DPG), and one unidentified glycolipid (GL). Minor polar lipids were one unidentified aminolipid (AL), one unidentified phospholipid (PL), and three unidentified lipids (L1-L3). Based on these results, strain ChDC PVNT-B20T is considered to represent a novel species of the genus Paenibacillus, for which the name Paenibacillus oralis sp. nov. is proposed. Type strain is ChDC PVNT-B20T (= KCOM 3021T = JCM 33462 T).

Correction to: Genome-Based Reclassification of Fusobacterium nucleatum Subspecies at the Species Level.

The original version of this article contained errors in the description of novel species. These errors are corrected with this corrigendum.

Osmunda japonica Extract Suppresses Pro-Inflammatory Cytokines by Downregulating NF-κB Activation in Periodontal Ligament Fibroblasts Infected with Oral Pathogenic Bacteria.

Periodontal diseases are caused by bacterial infection and may progress to chronic dental disease; severe inflammation may result in bone loss. Therefore, it is necessary to prevent bacterial infection or control inflammation. Periodontal ligament fibroblasts (PDLFs) are responsible for the maintenance of tissue integrity and immune and inflammatory events in periodontal diseases. The formation of bacterial complexes by Fusobacterium nucleatum and Porphyromonas gingivalis is crucial in the pathogenesis of periodontal disease. F. nucleatum is a facultative anaerobic species, considered to be a key mediator of dental plaque maturation and aggregation of other oral bacteria. P. gingivalis is an obligate anaerobic species that induces gingival inflammation by secreting virulence factors. In this study, we investigated whether Osmunda japonica extract exerted anti-inflammatory effects in primary PDLFs stimulated by oral pathogens. PDLFs were stimulated with F. nucleatum or P. gingivalis. We showed that pro-inflammatory cytokine (IL-6 and IL-8) expression was induced by LPS or bacterial infection but decreased by treatment with O. japonica extract following bacterial infection. We found that the activation of NF-κB, a transcription factor for pro-inflammatory cytokines, was modulated by O. japonica extract. Thus, O. japonica extract has immunomodulatory activity that can be harnessed to control inflammation.

Blautia argi sp. nov., a new anaerobic bacterium isolated from dog faeces.

Two isolates of a Gram-positive, non-motile, coccoid or oval-shaped anaerobic bacterium, designated strains N6H1-15T and YH1_16, were isolated from faecal samples obtained from a mature dog. Analysis of 16S rRNA gene sequences indicated that the isolates belonged to the Blautia coccoidesrRNA gene group (cluster XIVa) and were closely related to Blautia hansenii KCTC 5951T, Blautia stercoris KCTC 5981T, Blautia producta producta KCTC 3695T and B. coccoides DSM 15327T, with 96.7, 94.4, 94.2 and 93.9 % sequence similarity, respectively. The two isolates contained m-diaminopimelic acid within their peptidoglycans. The major polar lipids were diphosphatidylglycerol and phosphatidylglycerol, and the major fatty acids were C16 : 0 (18.5 %), C16 : 0 (18.0 %) and C18 : 1cis 9 (16.2 %). The predominant metabolic end products of glucose fermentation were acetic and lactic acids, and the G+C content was 44.2 mol%. Thus, the polyphasic data suggest that the two new isolates represent a new species, proposed as Blautia argi sp. nov. The type strain is N6H1-15T (=KCTC 15426=JCM 31394).

Clostridium vitabionis sp. nov., isolated from the large intestine of a mini-pig.

An obligately anaerobic, Gram-stain-negative, spore-forming, short rod-shaped bacterium, designated strain YH- T4B42T, was isolated from the large intestine of a mini-pig. Phylogenetic analysis based on 16S rRNA gene sequences indicated that the isolate belongs to the genus Clostridium and is most closely related to Clostridium aminophilum KCTC 5424T, Clostridium symbiosum KCTC 15329T and Clostridium butyricum KCTC 1871T, with 95.5, 92.4 and 83.0 % sequence similarity, respectively. The average nucleotide identity values for strain YH-T4B42T and the closest related strains were lower than 72 %. The G+C content of the isolate was 55.8 mol%. The cell-wall peptidoglycan was A1γ type and contained meso-diaminopimelic acid. The predominant fatty acids were C16 : 0, C18 : 1 cis 9, C14 : 0 and C18 : 0. The major end products of glucose fermentation were lactate, formate and acetate, with a minor amount of butyrate. Based on its phenotypic, phylogenetic and chemotaxonomic properties, a novel species, Clostridium vitabionis sp. nov., is proposed for strain YH-T4B42T (=KCTC 25105T=NBRC 114767T).

Description of Paenibacillus dokdonensis sp. nov., a new bacterium isolated from soil.

Two strains isolated from soil samples were designated as YH-JAE5T and YH-JAE2. The isolates were facultative anaerobic, Gram-stain-variable, motile, rod-shaped bacteria. Phylogenetic analysis indicated that the isolates belonged to the genus Paenibacillus, but the 16S rRNA gene sequence similarities were <98 % when compared with other species within the genus. Analysis of rpoB gene revealed the isolates formed a sub-cluster with P. chibensis. The only menaquinone identified was MK-7. The two isolates contained meso-diaminopimelic acid within their cell wall peptidoglycan. The major polar lipids were diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine, phospholipid, aminophospholipids, and lipids. The major fatty acids were C15 : 0 anteiso and C15 : 0 iso. The average nucleotide identity, average amino acid identity, and digital DNA-DNA hybridization values between isolate YH-JAE5T and the most closely related reference strain (Paenibacillus chibensis KCTC 3758T) were 81.7, 84.8 and 23.4 %, respectively. The G+C content of the genomic DNA was 47.4 mol%. Thus, the polyphasic data revealed that YH-JAE2 (=KCTC 43239=JCM 34435) and YH-JAE5T (=KCTC 43059=JCM 33533) represent a new species. The name Paenibacillus dokdonensis sp. nov. is proposed.

Streptococcus chosunense sp. nov., Isolated from Human Postoperative Maxillary Cyst.

A novel facultative anaerobic, non-spore forming, non-motile, and Gram-stain-positive coccus, designated strain ChDC B353T, was isolated from human postoperative maxillary cyst. The 16S ribosomal RNA gene (16S rDNA) sequence of the strain was most closely related to those of Streptococcus pseudopneumoniae ATCC BAA-960T (99.4%), Streptococcus mitis NCTC 12261T (99.3%), and Streptococcus pneumoniae NCTC 7465T (99.2%). The major fatty acids of the strain were C16:0 (43.2%) and C18:1 ω6c/C18:1 ω7c (20.2%). The genome of strain ChDC B353T was composed of 1,902,053 bps. The DNA G+C content of the strain was 40.2 mol%. Average nucleotide identity (ANI) values between strain ChDC B353T and S. pseudopneumoniae ATCC BAA-960T, S. mitis NCTC 12261T, and S. pneumoniae NCTC 7465T were 91.9%, 93.5%, and 91.3%, respectively. Genome-to-genome distance (GGD) values between strain ChDC B353T and S. pseudopneumoniae ATCC BAA-960T, S. mitis NCTC 12261T, or S. pneumoniae NCTC 7465T were 46.6% (44.0-49.2%), 53.2% (50.5-55.9%), and 46.0% (43.5-48.7%), respectively. The threshold values of ANI and GGD for species discrimination are 95-96% and 70%, respectively. These results reveal that strain ChDC B353T (= KCOM 1699T = JCM 33453T) is a novel species belonging to genus Streptococcus, for which a name of Streptococcus chosunense sp. nov. is proposed.

Streptococcus gwangjuense sp. nov., Isolated from Human Pericoronitis.

A novel facultative anaerobic, Gram-stain-negative coccus, designated strain ChDC B345T, was isolated from human pericoronitis lesion and was characterized by polyphasic taxonomic analysis. The 16S ribosomal RNA gene (16S rDNA) sequence revealed that the strain belonged to the genus Streptococcus. The 16S rDNA sequence of strain ChDC B345T was most closely related to those of  Streptococcus mitis NCTC 12261T (99.5%) and Streptococcus pseudopneumoniae ATCC BAA-960T (99.5%). Complete genome of strain ChDC B345T was 1,972,471 bp in length and the G + C content was 40.2 mol%. Average nucleotide identity values between strain ChDC B345T and S. pseudopneumoniae ATCC BAA-960T or S. mitis NCTC 12261T were 92.17% and 93.63%, respectively. Genome-to-genome distance values between strain ChDC B345T and S. pseudopneumoniae ATCC BAA-960T or S. mitis NCTC 12261T were 47.8% (45.2-50.4%) and 53.0% (51.0-56.4%), respectively. Based on these results, strain ChDC B345T (= KCOM 1679T = JCM 33299T) should be classified as a novel species of genus Streptococcus, for which we propose the name Streptococcus gwangjuense sp. nov.

Streptococcus periodonticum sp. nov., Isolated from Human Subgingival Dental Plaque of Periodontitis Lesion.

A novel facultative anaerobic and Gram-stain-positive coccus, designated strain ChDC F135T, was isolated from human subgingival dental plaque of periodontitis lesion and was characterized by polyphasic taxonomic analysis. The 16S rRNA gene (16S rDNA) sequence of strain ChDC F135T was closest to that of Streptococcus sinensis HKU4T (98.2%), followed by Streptococcus intermedia SK54T (97.0%), Streptococcus constellatus NCTC11325T (96.0%), and Streptococcus anginosus NCTC 10713T (95.7%). In contrast, phylogenetic analysis based on the superoxide dismutase gene (sodA) and the RNA polymerase beta-subunit gene (rpoB) showed that the nucleotide sequence similarities of strain ChDC F135T were highly similar to the corresponding genes of S. anginosus NCTC 10713T (99.2% and 97.6%, respectively), S. constellatus NCTC11325T (87.8% and 91.4%, respectively), and S. intermedia SK54T (85.8% and 91.2%, respectively) rather than those of S. sinensis HKU4T (80.5% and 82.6%). The complete genome of strain ChDC F135T consisted of 1,901,251 bp and the G+C content was 38.9 mol %. Average nucleotide identity value between strain ChDC F135T and S. sinensis HKU4T or S. anginosus NCTC 10713T were 75.7% and 95.6%, respectively. The C14:0 composition of the cellular fatty acids of strain ChDC F135T (32.8%) was different from that of S. intermedia (6-8%), S. constellatus (6-13%), and S. anginosus (13-20%). Based on the results of phylogenetic and phenotypic analysis, strain ChDC F135T (= KCOM 2412T = JCM 33300T) was classified as a type strain of a novel species of the genus Streptococcus, for which we proposed the name Streptococcus periodonticum sp. nov.