Yun Kyong Lim

Antimicrobial effect of linalool and α-terpineol against periodontopathic and cariogenic bacteria

Linalool and α-terpineol exhibited strong antimicrobial activity against periodontopathic and cariogenic bacteria. However, their concentration should be kept below 0.4 mg/ml if they are to be used as components of toothpaste or gargling solution. Moreover, other compounds with antimicrobial activity against periodontopathic and cariogenic bacteria should be used in combination.

Antimicrobial effect of Korean propolis against the mutans streptococci isolated from Korean

The aim of this study was to determine the optimal concentration of Korean propolis against clinical isolates of mutans streptococci (MS) from Koreans. The antimicrobial activity was evaluated using the minimum inhibitory concentration (MIC) and time-kill curves against mutans streptococci. The MIC90 values of propolis for MS were 35 μg/ml. Propolis had a bacteriostatic effect on Streptococcus mutans ATCC 25175T and bactericidal effects on Streptococcus sobrinus ATCC 33478T at > 2×MIC (70 μg/ml). These results suggest that the propolis can be used in the development of oral hygiene products for the prevention of dental caries.

NOX1/2 activation in human gingival fibroblasts by Fusobacterium nucleatum facilitates attachment of Porphyromonas gingivalis

Periodontal diseases are infectious polymicrobial inflammatory diseases that lead to destruction of the periodontal ligament, gingiva, and alveolar bone. Sequential colonization of a broad range of bacteria, including Fusobacterium nucleatum and Porphyromonas gingivalis, is an important phenomenon in this disease model. F. nucleatum is a facultative anaerobic species thought to be a key mediator of dental plaque maturation due to its extensive coaggregation with other oral bacteria, while P. gingivalis is an obligate anaerobic species that induces gingival inflammation by secreting various virulence factors. The formation of a bacterial complex by these two species is central to the pathogenesis of periodontal disease. Reactive oxygen species (ROS) are produced during bacterial infections and are involved in intracellular signaling. However, the impact of oral bacteria-induced ROS on the ecology of F. nucleatum and P. gingivalis has yet to be clarified. In the present study, we investigated ROS production induced in primary human oral cells by F. nucleatum and P. gingivalis and its effect on the formation of their bacterial complexes and further host cell apoptosis. We found that in primary human gingival fibroblasts (GFs), two NADPH oxidase isoforms, NOX1 and NOX2, were activated in response to F. nucleatum infection but not P. gingivalis infection. Accordingly, increased NADPH oxidase activity and production of superoxide anion were observed in GFs after F. nucleatum infection, but not after P. gingivalis infection. Interestingly, in NOX1, NOX2, or NOX1/NOX2 knockdown cells, the number of P. gingivalis decreased when the cells were coinfected with F. nucleatum. A similar pattern of host cell apoptosis was observed. This implies that F. nucleatum contributes to attachment of P. gingivalis by triggering activation of NADPH oxidase in host cells, which may provide an environment more favorable to strict anaerobic bacteria and have a subsequent effect on apoptosis of host cells.

Draft Genome Sequence of Fusobacterium nucleatum subsp. fusiforme ATCC 51190T

Fusobacterium nucleatum, one of the major causative bacteria of periodontitis, is classified into five subspecies (nucleatum, polymorphum, vincentii, animalis, and fusiforme) on the basis of the several phenotypic characteristics and DNA homology. This is the first report of the draft genome sequence of F. nucleatum subsp. fusiforme ATCC 51190(T).

Draft Genome Sequence of Fusobacterium nucleatum subsp. animalis ChDC F324, Isolated from a Human Subgingival Plaque in the Republic of Korea

ABSTRACT Five subspecies of Fusobacterium nucleatum have been classified: animalis, nucleatum, polymorphum, vincentii, and fusiforme. F. nucleatum subsp. animalis ChDC F324 (KCOM 1325) was isolated from a human subgingival plaque in the Republic of Korea. Here, we report the draft genome sequence of the strain.

Draft Genome Sequence of Fusobacterium nucleatum ChDC F128, Isolated from a Periodontitis Lesion

Fusobacterium nucleatum is classified into five subspecies. F. nucleatum ChDC F128 was isolated from a periodontitis lesion and proposed as a new subspecies based on the comparison of the nucleotide sequences of the RNA polymerase beta subunit and zinc protease genes. Here, we report the draft genome sequence of the strain.

In vitro Antimicrobial Activities of 1-Methoxyficifolinol, Licorisoflavan A, and 6,8-Diprenylgenistein against Streptococcus mutans

The objective of the study was to investigate the antimicrobial effects of purified single compounds from ethanol-extracted licorice root on Streptococcus mutans. The crude licorice root extract (CLE) was obtained from Glycyrrhiza uralensis, which was subjected to column chromatography to separate compounds. Purified compounds were identified by mass spectrometry and nuclear magnetic resonance. Antimicrobial activities of purified compounds from CLE were evaluated by determining the minimum inhibitory concentration and by performing time-kill kinetics. The inhibitory effects of the compounds on biofilm development were evaluated using crystal violet assay and confocal microscopy. Cell toxicity of substances to normal human gingival fibroblast (NHGF) cells was tested using a methyl thiazolyl tetrazolium assay. Chlorhexidine digluconate (CHX) was used in the control group. Three antimicrobial flavonoids, 1-methoxyficifolinol, licorisoflavan A, and 6,8-diprenylgenistein, were isolated from the CLE. We found that the three flavonoids and CHX had bactericidal effects on S. mutans UA159 at the concentration of ≥4 and ≥1 µg/ml, respectively. The purified compounds completely inhibited biofilm development of S. mutans UA159 at concentrations over 4 μg/ml, which was equivalent to 2 μg/ml of CHX. Confocal analysis showed that biofilms were sparsely scattered in the presence of over 4 μg/ml of the purified compounds. However, the three compounds purified from CLE showed less cytotoxic effects on NHGF cells than CHX at these biofilm-inhibitory concentrations. Our results suggest that purified flavonoids from CLE can be useful in developing oral hygiene products, such as gargling solutions and dentifrices for preventing dental caries.

Draft Genome Sequence of the Novel Peptoniphilus sp. Strain ChDC B134, Isolated from a Human Periapical Abscess Lesion

ABSTRACT The genus Peptoniphilus comprises butyrate-producing, nonsaccharolytic species that use peptone and amino acids as major energy sources. The novel Peptoniphilus sp. strain ChDC B134 (=KCOM 1628) was isolated from a human periapical abscess lesion. Here, we report the draft genome sequence of the strain.

Genome-Based Reclassification of Fusobacterium nucleatum Subspecies at the Species Level

Fusobacterium nucleatum is classified as four subspecies, subsp. nucleatum, polymorphum, vincentii, and animalis, based on DNA–DNA hybridization (DDH) patterns, phenotypic characteristics, and/or multilocus sequence analysis (MLSA). The gold standards for classification of bacterial species are DDH and 16S ribosomal RNA gene (16S rDNA) sequence homology. The thresholds of DDH and 16S rDNA similarity for delineation of bacterial species have been suggested to be >70 and 98.65%, respectively. Average nucleotide identity (ANI) and genome-to-genome distance (GGD) analysis based on genome sequences were recently introduced as a replacement for DDH to delineate bacterial species with ANI (95–96%) and GGD (70%) threshold values. In a previous study, F. hwasookii was classified as a new species based on MLSA and DDH results. 16S rDNA similarity between F. hwasookii type strain and F. nucleatum subspecies type strains was higher than that between F. nucleatum subspecies type strains. Therefore, it is possible that the four F. nucleatum subspecies can be classified as Fusobacterium species. In this study, we performed ANI and GGD analyses using the genome sequences of 36 F. nucleatum, five F. hwasookii, and one Fusobacterium periodonticum strain to determine whether the four F. nucleatum subspecies could be classified as species using OrthoANI and ANI web-based softwares provided by ChunLab and Kostas lab, respectively, and GGD calculator offered by German Collection of Microorganisms and Cell Cultures. ANI values calculated from OrthoANI and ANI calculators between the type strains of F. nucleatum subspecies ranged from 89.80 to 92.97 and from 90.40 to 91.90%, respectively. GGD values between the type strains of F. nucleatum subspecies ranged from 42.3 to 46.0%. ANI and GGD values among strains belonging to the same F. nucleatum subspecies, subsp. nucleatum, subsp. polymorphum, subsp. vincentii, and subsp. animalis were >96 and >68.2%, respectively. These results strongly suggest that F. nucleatum subsp. nucleatum, subsp. polymorphum, subsp. vincentii, and subsp. animalis should be classified as F. nucleatum, F. polymorphum, F. vincentii, and F. animalis, respectively.

Draft Genome Sequences of Fusobacterium nucleatum ChDC F145, ChDC F174, ChDC F206, and ChDC F300, Isolated from Human Subgingival Plaques in the Republic of Korea.

ABSTRACT Recently, five strains were isolated from human subgingival plaques and were proposed as a novel subspecies of Fusobacterium nucleatum. Here, we report the draft genome sequences of the strains, except one for which the draft sequence was already introduced.