Seho Cha

Porphyromonas gingivalis-derived lipopolysaccharide-mediated activation of MAPK signaling regulates inflammatory response and differentiation in human periodontal ligament fibroblasts

Porphyromonas gingivalis (P.g.), which is a potential pathogen for periodontal diseases, contains lipopolysaccharide (LPS), and this endotoxin stimulates a variety of cellular responses. At present, P.g.-derived LPS-induced cellular responses in human periodontal ligament fibroblasts (PDLFs) are not well characterized. Here, we demonstrate that P.g-derived LPS regulates inflammatory responses, apoptosis and differentiation in PDLFs. Interleukin-6 (IL-6) and -8 (IL-8) were effectively upregulated by treatment of P.g.-derived LPS, and we confirmed apoptosis markers including elevated cytochrome c levels, active caspase-3 and morphological change in the presence of P.g.-derived LPS. Moreover, when PDLFs were cultured with differentiation media, P.g.-derived LPS reduced the expression of differentiation marker genes, as well as reducing alkaline phosphatase (ALP) activity and mineralization. P.g.-derived LPS-mediated these cellular responses were effectively abolished by treatment of mitogen-activated protein kinase (MAPK) inhibitors. Taken together, our results suggest that P.g.-derived LPS regulates several cellular responses via activation of MAPK signaling pathways in PDLFs.

Spirosoma pulveris sp. nov., a bacterium isolated from a dust sample collected at Chungnam province, South Korea

Strain JSH 5-14T, a Gram-negative, non-motile, and curved rod-shaped bacterium, was isolated from a dust sample collected at Nonsan, Chungnam province, South Korea, and was characterized to determine its taxonomic position. Phylogenetic analysis based on the 16S rRNA gene sequence of strain JSH 5-14T revealed that it belongs to the genus Spirosoma, family Cytophagaceae, class Cytophagia. The highest degree of sequence similarities of strain JSH 5-14T were found with Spirosoma liguale DSM 74T (97.8%) and Spirosoma endophyticum EX 36T (96.2%). The predominant fatty acids were summed feature 3 (composed of C16:1ω7c/C16:1ω6c) and C16:1ω5c. The major polar lipid was phosphatidylethanolamine, and the predominant respiratory quinone was MK-7. Based on the phylogenetic, chemotaxonomic, and phenotypic data, we propose the strain JSH 5-14T (=KCTC 42550T =JCM 30688T =KEMB 9004-165T) should be classified as a type strain of a novel species, for which the name Spirosoma pulveris sp. nov., is proposed.

Development of animal experimental periodontitis models

Purpose An animal periodontitis model is essential for research on the pathogenesis and treatment of periodontal disease. In this study, we have introduced a lipopolysaccharide (LPS) of a periodontal pathogen to the alveolar bone defect of experimental animals and investigated its suitability as a periodontitis model. Methods Alveolar bone defects were made in both sides of the mandibular third premolar region of nine beagle dogs. Then, the animals were divided into the following groups: silk ligature tied on the cervical region of tooth group, Porphyromonas gingivalis LPS (P.g. LPS)-saturated collagen with silk ligature group, and no ligature or P.g. LPS application group as the control. The plaque index and gingival index were measured at 0 and 4 weeks postoperatively. The animals were then euthanized and prepared for histologic evaluation. Results The silk ligature group and P.g. LPS with silk ligature group showed a significantly higher plaque index at 4 weeks compared to the control (P<0.05). No significant difference was found in the plaque index between the silk ligature group and P.g. LPS with silk ligature group. The P.g. LPS with silk ligature group showed a significantly higher gingival index compared to the silk ligature group or the control at 4 weeks (P<0.05). Histologic examination presented increased inflammatory cell infiltration in the gingival tissue and alveolar bone of the P.g. LPS with silk ligature group. Conclusions An additional P.g. LPS-saturated collagen with silk ligature ensured periodontal inflammation at 4 weeks. Therefore, P.g. LPS with silk ligature application to surgically created alveolar bone defects may be a candidate model for experimental periodontitis.

Flavisolibacter swuensis sp. nov. Isolated from Soil

A Gram-staining-negative, non-motile, non-spore-forming, and rod-shaped bacterium designated as strain SR2-4-2T was isolated from soil in South Korea. Phylogenetic analysis based on 16S rRNA gene sequence of strain SR2-4-2T revealed that it belonged to the genus of Flavisolibacter, family of Chitinophagaceae, and class of Sphingobacteriia. It shared sequence similarities with Flavisolibacter ginsengisoli Gsoil 643T (96.4%), Flavisolibacter ginsengiterrae Gsoil 492T (96.3%), and Flavisolibacter rigui 02SUJ3T (93.0%). Chemotaxonomic data revealed that its predominant fatty acids were iso-C15:0 (26.4%) and iso-C17:0 3OH (10.7%). Its major polar lipid was phosphatidylethanolamine (PE) and its predominant respiratory quinone was MK-7. The G+C content of genomic DNA of the strain SR2-4-2T DNA was 45.0%. Based on the phylogenetic, chemotaxonomic, and phenotypic data, the strain SR2-4-2T (=JCM 19974T =KEMB 9004–156T) is classified as a type strain of a novel species for which the name of Flavisolibacter swuensis sp. nov. is proposed.

Synergic induction of human periodontal ligament fibroblast cell death by nitric oxide and N-methyl-D-aspartic acid receptor antagonist

Purpose Nitric oxide (NO) has been known as an important regulator of osteoblasts and periodontal ligament cell activity. This study was performed to investigate the relationship between NO-mediated cell death of human periodontal ligament fibroblasts (PDLFs) and N-methyl-D-aspartic acid (NMDA) receptor antagonist (+)-5-methyl-10, 11-dihydro-5H-dibenzo[a,d]cyclohepten-5, 10-imine hydrogen maleate (MK801). Methods Human PDLFs were treated with various concentrations (0 to 4 mM) of sodium nitroprusside (SNP) with or without 200 µM MK801 in culture media for 16 hours and the cell medium was then removed and replaced by fresh medium containing MTS reagent for cell proliferation assay. Western blot analysis was performed to investigate the effects of SNP on the expression of Bax, cytochrome c, and caspase-3 proteins. The differences for each value among the sample groups were compared using analysis of variance with 95% confidence intervals. Results In the case of SNP treatment, as a NO donor, cell viability was significantly decreased in a concentration-dependent manner. In addition, a synergistic effect was shown when both SNP and NMDA receptor antagonist was added to the medium. SNP treated PDLFs exhibited a round shape in culture conditions and were dramatically reduced in cell number. SNP treatment also increased levels of apoptotic marker protein, such as Bax and cytochrome c, and reduced caspase-3 in PDLFs. Mitogen-activated protein kinase signaling was activated by treatment of SNP and NMDA receptor antagonist. Conclusions These results suggest that excessive production of NO may induce apoptosis and that NMDA receptor may modulate NO-induced apoptosis in PDLFs.

Lysobacter humi sp. nov., isolated from soil

A yellow-pigmented and strictly aerobic bacterial strain, designated FJY8T, was isolated from the soil of Goyang, South Korea. The cells of FJY8T were Gram-reaction-negative, non-motile rods. Colonies were circular, convex and transparent. Strain FJY8T grew optimally at 30 °C, with 0 % (w/v) NaCl and at pH 8. Phylogenetic analysis of the 16S rRNA gene sequence of FJY8T revealed a clear affiliation of this bacterium to the family Lysobacteraceae, and it was related to members of the genus Lysobacter, with Lysobacter xinjiangensis KCTC 22558T being its closest relative (98.7 % sequence similarity). The DNA G+C content was 68.0±0.4 mol%. Diphosphatidylglycerol, phosphatidylethanolamine and phosphatidylglycerol were identified as the major polar lipids, and an unidentified phospholipid and two unidentified aminophospholipids were also detected as the minor polar lipids. The major fatty acids were iso-C16 : 0, summed feature 9 (iso-C17 : 1ω9c and/or C16 : 0 10-methyl) and iso-C15 : 0. Only ubiquinone-8 (Q-8) was detected as the isoprenoid quinone. DNA-DNA hybridization values of strain FJY8T with Lysobacter xinjiangensisRCML-52T and Lysobacter mobilis9NM-14T were 55.8±2.0 and 45.2±4.8 %, respectively. On the basis of DNA-DNA hybridization, phylogenetic distinctiveness, and some physiological and biochemical tests, strain FJY8T (=KCTC 42810T=JCM 31019T) represents a novel species of the genus Lysobacter, for which the name Lysobacter humi sp. nov. is proposed.

Aestuariibaculum marinum sp. nov., a marine bacterium isolated from seawater in South Korea

A Gram-negative, non-motile, aerobic bacterium, designated strain IP7T, was isolated from seawater at the shore of the Incheon Eulwang-ri beach, South Korea. Cells of strain IP7T are straight or slightly rod-shaped and colonies are round, convex and orange-yellow. Strain IP7T is flexirubin-negative, mild halophile, catalase-and oxidase-positive, and produces a yellow-orange carotenoid pigment. Growth is optimal at 30°C, pH 7–9, and 2.0–4.0% NaCl (w/v). On the basis of 16S rRNA gene sequence similarity, strain IP7T is affiliated with genus Aestuariibaculum in the family Flavobacteriaceae, the closest relative being Aestuariibaculum suncheonense SC17T (98.3% sequence similarity). The DNA G + C content of the novel strain is 37.4 mol%. The only quinone is MK-6 menaquinone. Iso-branched C15:0, iso-branched C15:1 G, and iso-branched C17:0 3-OH are major fatty acids. The major polar lipids are phosphatidylethanolamine, an unidentified aminoglycolipid and two unidentified glycolipids. The DNA-DNA hybridization value of strain IP7T with Aestuariibaculum suncheonense SC17T is 28.87%. Based on the collective DNA-DNA hybridization, biochemical, phylogenetic and physiological data, we report a novel species of the genus Aestuariibaculum for which the name Aestuariibaculum marinum sp. nov. is proposed. The type strain is IP7T (= KCTC 52521T = JCM 31725T).

Paenibacillus mobilis sp. nov., a Gram-stain-negative bacterium isolated from soil

A novel Gram-stain-negative bacterium, designated strain S8T, was isolated from a soil sample obtained in Gyeonggi Province, Republic of Korea. Cells of strain S8T were endospore-forming, motile by means of peritrichous flagella, and rod-shaped. S8T colonies were round, convex, wavy and white. Strain S8T grew optimally at 37 °C, pH 6-8, and up to 2.0 % (w/v) NaCl. Based on 16S rRNA gene sequence similarity, strain S8T was affiliated with the genus Paenibacillus in the family Paenibacillaceae and was most closely related to Paenibacillus yonginensis DCY84T and Paenibacillus physcomitrellae XBT (98.8 and 97.1 % sequence similarity). The DNA G+C content of the novel strain was 53.1±0.3 mol%. Strain S8T contained diphosphatidylglycerol, phosphatidylglycerol, two phospholipids, four aminophospholipids, an aminolipid and three unidentified lipids. The major fatty acid was anteiso-branched C15 : 0. The quinone was menaquinone MK-7. The peptidoglycan of strain S8T contained meso-diaminopimelic acid. The DNA-DNA hybridization values of strain S8T with P. yonginensis KCTC 33428T and P. physcomitrellae DSM 29851T were 44 % and 32 %, respectively. Data from the DNA-DNA hybridization, biochemical, phylogenetic and physiological analyses indicate that strain S8T (=KCTC 33848T=JCM 31672T) represents a novel species of the genus Paenibacillus, for which the name Paenibacillus mobilis sp. nov. is proposed.

Ensifer collicola sp. nov., a bacterium isolated from soil in South Korea

Strain Mol12T, which presented in the form of Gram-negative, motile, non-spore forming rod-shaped, was isolated from soil in South Korea and characterized to determine its taxonomic position. The strain grew at 20–30°C (optimum 30°C) and pH 7.0–10.0 (optimum pH 8.0) with 1% (w/v) NaCl. Phylogenetic analysis based on 16S rRNA gene sequences showed that the strain Mol12T was most closely related to Ensifer terangae LMG 7834T (96.78%), Rhizobium daejeonense KCTC 12121T (96.43%), Ensifer adhaerens Casida AT (96.28%). Chemotaxonomic data showed that the predominant fatty acids were Summed Feature 8 (C18:1ω7c and/or C18:1ω6c; 53.02%) and C18:1ω7c 11-methyl (24.01%). Its complex polar lipid contained major amounts of diphosphatidylglycerol (DPG), phosphatidylethanolamine (PE) and Q-10 as the predominant ubiquinone. The DNA G+C content of strain Mol12T was determined to be 60.9 mol%. Based on the phylogenetic, chemotaxonomic, and phenotypic data, strain Mol12T (=KCTC 42816T =JCM 31049T) ought to be classified as a type strain of a novel species, for which the name Ensifer collicola sp. nov. is proposed.

Hydrogenophaga soli sp. nov., isolated from rice field soil

A novel Gram-stain-negative bacterial strain, designated strain S10T, was isolated from soil collected in a rice field in Goyang, South Korea. Cells of strain S10T were strictly aerobic, motile and rod-shaped. Colonies were round, convex, smooth and white. The strain grew optimally at 37 °C, pH 7.0 and 0 % (w/v) NaCl. Phylogenetic analysis of the 16S rRNA gene sequence of strain S10T revealed that the bacterium belongs to the family Comamonadaceae and is related to members of the genus Hydrogenophaga, with Hydrogenophaga caeni EMB71T being its closest relative (97.9 % sequence similarity). The DNA G+C content of strain S10T was 68.2 mol%. Strain S10T contained phosphatidylethanolamine and diphosphatidylglycerol as the major polar lipids. The major fatty acids were C16 : 0 and summed feature 3 (C16 : 1ω7c and/or iso-C15 : 0 2-OH). The predominant respiratory quinone was ubiquinone Q-8. DNA-DNA hybridization values of strain S10T with Hydrogenophaga caeni KCTC 12613T, Hydrogenophaga atypica DSM 15342T and Hydrogenophaga defluvii DSM 15341T were 16.1±4.8, 49.0±3.2 and 21.9±8.8 %, respectively. Based on phylogenetic distinctiveness, DNA-DNA hybridization and specific physiological and biochemical characteristics, strain S10T (=KCTC 52520T=JCM 31711T) is classified as a novel species of the genus Hydrogenophaga, for which the name Hydrogenophagasoli sp. nov. is proposed.