Staphylococcus aureus produces many virulence factors, including toxins, immune-modulatory and exoenzymes. Previous studies involving the analysis of expression were mainly performed by in vitro experiments using bacterial medium. However, when S. infects a host, growth conditions are quite different from those medium, which may be related to factors host. In this study, we investigated grown calf serum. The hemolysins, enterotoxins, proteases, iron acquisition was significantly increased...

Staphylococcus aureus is a major pathogen in humans and causes serious problems due to antibiotic resistance. We investigated the antimicrobial effect of glycyrrhetinic acid (GRA) its derivatives against 50 clinical S. strains, including 18 methicillin-resistant strains. The minimum inhibitory concentrations (MICs) GRA, dipotassium glycyrrhizate, disodium succinoyl glycyrrhetinate (GR-SU), stearyl glycyrrhetinyl stearate were evaluated various Additionally, we bactericidal effects GRA GR-SU...

Staphylococcus aureus uses two-component systems (TCSs) to adapt stressful environmental conditions. To colonize a host, S. must resist bacteriocins produced by commensal bacteria. In comprehensive analysis using individual TCS inactivation mutants, the of two TCSs, graRS and braRS, significantly increased susceptibility class I bacteriocins, nukacin ISK-1 nisin A, vraSR slightly ISK-1. addition, ABC transporters (BraAB VraDE) regulated BraRS one transporter (VraFG) GraRS were associated...

Streptococcus mutans produces bacteriocins that show antibacterial activity against several bacteria. However, comprehensive analysis of these has not been well done. In this study, we isolated 125 S. strains from volunteers and determined their whole genome sequence. Based on the analysis, distribution each bacteriocin gene (mutacins I-IV, K8 Smb) was investigated. We found 17, 5, 2 showing 100% matches with mutacin I, II III, respectively. Five III-positive had mismatches compared to...

ABSTRACT Large numbers of bacteria coexist in the oral cavity. Streptococcus sanguinis , one major dental plaque, produces hydrogen peroxide (H 2 O ), which interferes with growth other bacteria. mutans a cariogenic bacterium, can S. but to do so, it needs means detoxifying H produced by . In this study, we investigated association three oxidative stress factors, Dpr, superoxide dismutase (SOD), and AhpCF, resistance The knockout dpr sod significantly increased susceptibility while ahpCF had...

Bacterial cell surface charge is responsible for susceptibility to cationic antimicrobial peptides. Previously, Staphylococcus aureus dlt and mprF were identified as factors conferring a positive upon surfaces. In this study, we investigated the regulation of during growth. Using group S. MW2 mutants, which are gene-inactivated in 15 types two-component systems (TCSs), tested dltC expression found that two TCSs, aps agr, associated with growth phase-dependent manner. The first these, aps,...

Staphylococcus aureus is a major human pathogen that can colonize the nasal cavity, skin, intestine, and oral cavity as commensal bacterium. gp340, also known DMBT1 (deleted in malignant brain tumors 1), associated with epithelial differentiation innate immunity. In gp340 induces salivary aggregation several bacteria promotes bacterial adhesion to tissues such teeth mucosa. S. often isolated from but mechanism underlying its persistence remains unclear. this study, we investigated...

Tannerella forsythia is an anaerobic, Gram-negative bacterium involved in the so-called "red complex," which associated with severe and chronic periodontitis. The surface layer (S-layer) of T. composed cell glycoproteins, such as TfsA TfsB, known to play a role adhesion/invasion suppression proinflammatory cytokine expression. Here we investigated association this S-layer serum resistance coaggregation other oral bacteria. growth S-layer-deficient mutant bacterial medium containing more than...

Bacterial two-component systems (TCSs) have been demonstrated to be associated with not only the expression of virulence factors, but also susceptibility antibacterial agents. In Staphylococcus aureus, 16 types TCSs identified. We previously found that inactivation one uncharacterized TCS (designated as BceRS, MW gene ID: MW2545-2544) resulted in an increase bacitracin. this study, we focused on and tried identify TCS-controlled factors affecting two ABC transporters were One transporter...

Streptococcus mutans is a cariogenic pathogen that produces an extracellular polysaccharide (glucan) from dietary sugars, which allows it to establish reproductive niche and secrete acids degrade tooth enamel. While two enzymes (GlmS NagB) are known be key factors affecting the entrance of amino sugars into glycolysis cell wall synthesis in several other bacteria, their roles S. remain unclear. Therefore, we investigated GlmS NagB sugar metabolism determined whether they have effect on...

ABSTRACT The novel two-component systems NsrRS and LcrRS are individually associated with resistance against the distinct lantibiotics nisin A nukacin ISK-1 in Streptococcus mutans . regulates expression of NsrX, which is binding, ABC transporter LctFEG.

Streptococcus mutans is a cariogenic pathogen in humans. To persist the oral cavity, S. resistant against several antibacterial factors derived from host. In this study, we investigated mechanism of resistance to cationic antimicrobial peptides (AMPs), which are innate immune Because dltA-D (teichoic acid biosynthesis) was reported affect susceptibility AMPs other bacterial species, evaluated dltC knockout mutant human beta-defensin-1 (hBD1), hBD2, hBD3 and LL37. The exhibited significantly...

Staphylococcus epidermidis is a commensal bacterium in humans. To persist the bacterial flora of host, some bacteria produce antibacterial factors such as antimicrobial peptides known bacteriocins. In this study, we tried to isolate bacteriocin-producing S . strains. Among 150 isolates from oral cavities 287 volunteers, detected two strains, KSE56 and KSE650. Complete genome sequences strains confirmed that they carried epidermin-harboring plasmid pEpi56 nukacin IVK45-like-harboring pNuk650....

ABSTRACT Aggregatibacter actinomycetemcomitans is a Gram-negative facultative anaerobe and associated with periodontal disease. This bacterium exposed to environmental stresses, such as osmotic pressure, temperature shifts, pH antimicrobial substances, including reactive oxygen species (ROS), in the human oral cavity. The bacterial two-component system ArcAB modulates gene expression response changes, primarily by sensing pressure several pathogens belonging γ-proteobacteria. It also known...

Abstract Aim This study was undertaken to investigate the existence of a periodontopathic bacterium, Fusobacterium nucleatum , in chorionic tissues pregnant women, and effects F. on human chorion‐derived cells. Materials Methods Oral tissue samples were collected from 24 high‐risk women 15 normal women. The presence detected using polymerase chain reaction. Chorion‐derived cells Toll‐like receptor ( TLR )‐2 or ‐4 gene‐silenced stimulated with lipopolysaccharide LPS ). Interleukin IL )‐6...

Abstract Nisin A is a lantibiotic produced by Lactococcus lactis that widely used as food preservative. In Staphylococcus aureus , the BraRS two‐component system (TCS) senses nisin and regulates expression of ABC transporter VraDE, which responsible for resistance. this study, we exposed S. to sub‐minimum inhibition concentration obtained three spontaneous mutants were highly resistant lantibiotic, designated SAN ( resistant) 1, SAN8, SAN87. wild‐type strain, VraDE was induced A. contrast,...

Staphylococcus aureus is a pathogen and commensal bacterial species that found in humans. Bacterial two-component systems (TCSs) sense respond to environmental stresses, which include antimicrobial agents produced by other bacteria. In this study, we analyzed the relation between TCS SrrAB susceptibility hydrogen peroxide (H2O2) Streptococcus sanguinis, oral streptococcus. An srrA-inactivated S. mutant demonstrated low H2O2 sanguinis. We investigated expression of anti-oxidant factors...

Streptococcus mutans is a cariogenic bacterium that localizes in the oral cavity. Glycyrrhetinic acid (GRA) major component of licorice extract. GRA and several derivatives, including disodium succinoyl glycyrrhetinate (GR-SU), are known to have anti-inflammatory effects humans. In this study, antimicrobial effect its derivatives against S. UA159 strain were investigated. Minimum inhibitory concentrations (MICs) GR-SU showed antibacterial activity strain, whereas other tested did not....

Recently, the emergence of antibiotic-resistant bacteria has resulted in serious problems for chemotherapy. In addition, many antibacterial agents, such as disinfectants and food additives, are widely used. Therefore, there is a possibility that becoming resistant to some agents. this study, we investigated whether Staphylococcus aureus can become nisin A, one bacteriocins applied additive. We isolated highly A-resistant strain designated SAN2 displayed increased expression Pmt proteins,...

Staphylococcus aureus is a human pathogen, and S. bacteremia can cause serious problems in humans. To identify the genes required for bacterial growth calf serum (CS), library of mutants with randomly inserted transposons were analyzed CS, aspartate semialdehyde dehydrogenase (asd)-inactivated mutant exhibited significantly reduced CS compared wild type (WT). The also medium, mimicking concentrations amino acids glucose CS. Asd an essential enzyme biosynthesis lysine, methionine, threonine...

Streptococcus mutans is a major cause of tooth decay due to its promotion biofilm formation and acid production. Several plant extracts have been reported multiple biological activities such as anti-inflammation antibacterial effects. This study investigated the activity three extracts, phellodendron bark (PB), yucca, black ginger, found that PB had stronger effect than other extracts. Then, minimum inhibitory concentration (MIC) against 100 S. strains was investigated. The MIC range...