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Hiers RD, Khajotia SS, Merritt J, Esteban Florez FL. Optimization of an ultra-bright real-time high-throughput renilla luciferase assay for antibacterial assessment of Streptococcus mutans biofilms. Dent Mater 2024; 40:1313-1321. [PMID: 38876827 PMCID: PMC11330348 DOI: 10.1016/j.dental.2024.06.012] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2024] [Accepted: 06/05/2024] [Indexed: 06/16/2024]
Abstract
OBJECTIVE The present work demonstrates the optimization of a renilla-based real-time, ultra-bright, non-disruptive, high-throughput bioluminescence assay (HTS) to assess the metabolism of intact Streptococcus mutans biofilms and its utility in screening the antibacterial efficacy of experimental nanofilled dental adhesive resins containing varying concentrations of nitrogen-doped titanium dioxide nanoparticles (N_TiO2). METHODS Optimization of the assay was achieved by screening real-time bioluminescence changes in intact Streptococcus mutans biofilms imposed by the various experimental biofilm growth parameters investigated (bacterial strain, growth media, sucrose concentration, dilution factor, and inoculum volume). The optimized assay was then used to characterize the antibacterial efficacy of experimental nanofilled dental adhesive resins. The assay's ability to discriminate between bacteriostatic and bactericidal approaches was also investigated. RESULTS Relative Light Units (RLU) values from the HTS optimization were analyzed by multivariate ANOVA (α = 0.05) and coefficients of variation. An optimized HTS bioluminescence assay was developed displaying RLUs values (brightness) that are much more intense when comparing to other previously reported bioluminescence assays, thereby decreasing the error associated with bioluminescence assays and displaying better utility while investigating the functionalities of antimicrobial nanofilled experimental dental adhesive resins with proven long-term properties. SIGNIFICANCE The present study is anticipated to positively impact subsequent research on dental materials and oral microbiology because it serves as a valuable screening tool in metabolic-based assays with increased sensitivity and robustness. The assay reported is anticipated to be further optimized to be used as a co-reporter for other Luc based assays.
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Affiliation(s)
- Rochelle Denise Hiers
- The University of Oklahoma Health Sciences Center, Department of Restorative Sciences, Division of Dental Biomaterials, College of Dentistry, 1201 N. Stonewall Avenue, Oklahoma City, OK 73117, USA.
| | - Sharukh Soli Khajotia
- The University of Oklahoma Health Sciences Center, Department of Restorative Sciences, Division of Dental Biomaterials, College of Dentistry, 1201 N. Stonewall Avenue, Oklahoma City, OK 73117, USA.
| | - Justin Merritt
- Oregon Health & Science University, Department of Restorative Dentistry, School of Dentistry, MRB424, 3181 SW Sam Jackson Park Rd., Portland, OR 97239, USA.
| | - Fernando Luis Esteban Florez
- The University of Oklahoma Health Sciences Center, Department of Restorative Sciences, Division of Dental Biomaterials, College of Dentistry, 1201 N. Stonewall Avenue, Oklahoma City, OK 73117, USA.
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Merritt J, Kreth J. Illuminating the oral microbiome and its host interactions: tools and approaches for molecular microbiology studies. FEMS Microbiol Rev 2023; 47:fuac050. [PMID: 36549660 PMCID: PMC10719069 DOI: 10.1093/femsre/fuac050] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2022] [Accepted: 12/19/2022] [Indexed: 12/24/2022] Open
Abstract
Advancements in DNA sequencing technologies within the last decade have stimulated an unprecedented interest in the human microbiome, largely due the broad diversity of human diseases found to correlate with microbiome dysbiosis. As a direct consequence of these studies, a vast number of understudied and uncharacterized microbes have been identified as potential drivers of mucosal health and disease. The looming challenge in the field is to transition these observations into defined molecular mechanistic studies of symbiosis and dysbiosis. In order to meet this challenge, many of these newly identified microbes will need to be adapted for use in experimental models. Consequently, this review presents a comprehensive overview of the molecular microbiology tools and techniques that have played crucial roles in genetic studies of the bacteria found within the human oral microbiota. Here, we will use specific examples from the oral microbiome literature to illustrate the biology supporting these techniques, why they are needed in the field, and how such technologies have been implemented. It is hoped that this information can serve as a useful reference guide to help catalyze molecular microbiology studies of the many new understudied and uncharacterized species identified at different mucosal sites in the body.
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Affiliation(s)
- Justin Merritt
- Department of Restorative Dentistry, School of Dentistry, Oregon Health and Science University, Portland, OR, United States
- Department of Molecular Microbiology and Immunology, Oregon Health and Science University, Portland, OR 97239, United States
| | - Jens Kreth
- Department of Restorative Dentistry, School of Dentistry, Oregon Health and Science University, Portland, OR, United States
- Department of Molecular Microbiology and Immunology, Oregon Health and Science University, Portland, OR 97239, United States
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G C B, Zhou P, Naha A, Gu J, Wu C. Development of a xylose-inducible promoter and riboswitch combination system for manipulating gene expression in Fusobacterium nucleatum. Appl Environ Microbiol 2023; 89:e0066723. [PMID: 37695289 PMCID: PMC10537658 DOI: 10.1128/aem.00667-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2023] [Accepted: 07/05/2023] [Indexed: 09/12/2023] Open
Abstract
Inducible gene expression systems are important for studying bacterial gene function, yet most exhibit leakage. In this study, we engineered a leakage-free hybrid system for precise gene expression controls in Fusobacterium nucleatum by integrating the xylose-inducible expression system with the theophylline-responsive riboswitch. This innovative method enables concurrent control of target gene expression at both transcription and translation initiation levels. Using luciferase and the indole-producing enzyme tryptophanase (TnaA) as reporters, we demonstrated that the hybrid system displays virtually no observable signal in the absence of inducers. We employed this system to express FtsX, a protein related to fusobacterial cytokinesis, in an ftsX mutant strain, unveiling a dose-dependent manner in FtsX production. Without inducers, cells form long filaments, while increasing FtsX levels by increasing inducer concentrations led to a gradual reduction in cell length until normal morphology was restored. Crucially, this system facilitated essential gene investigation, identifying the signal peptidase lepB gene as vital for F. nucleatum. LepB's essentiality stems from depletion, affecting outer membrane biogenesis and cell division. This novel hybrid system holds the potential for advancing research on essential genes and accurate gene regulation in F. nucleatum. IMPORTANCE Fusobacterium nucleatum, an anaerobic bacterium prevalent in the human oral cavity, is strongly linked to periodontitis and can colonize areas beyond the oral cavity, such as the placenta and gastrointestinal tract, causing adverse pregnancy outcomes and promoting colorectal cancer growth. Given F. nucleatum's clinical significance, research is underway to develop targeted therapies to inhibit its growth or eradicate the bacterium specifically. Essential genes, crucial for bacterial survival, growth, and reproduction, are promising drug targets. A leak-free-inducible gene expression system is needed for studying these genes, enabling conditional gene knockouts and elucidating the importance of those essential genes. Our study identified lepB as the essential gene by first generating a conditional gene mutation in F. nucleatum. Combining a xylose-inducible system with a riboswitch facilitated the analysis of essential genes in F. nucleatum, paving the way for potential drug development targeting this bacterium for various clinical applications.
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Affiliation(s)
- Bibek G C
- Department of Microbiology & Molecular Genetics, The University of Texas Health Science Center, Houston, Texas, USA
| | - Peng Zhou
- Department of Microbiology & Molecular Genetics, The University of Texas Health Science Center, Houston, Texas, USA
| | - Arindam Naha
- Department of Microbiology & Molecular Genetics, The University of Texas Health Science Center, Houston, Texas, USA
| | - Jianhua Gu
- Houston Methodist Hospital Research Institute, Houston, Texas, USA
| | - Chenggang Wu
- Department of Microbiology & Molecular Genetics, The University of Texas Health Science Center, Houston, Texas, USA
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Dornelas-Figueira LM, Ricomini Filho AP, Junges R, Åmdal HA, Cury AADB, Petersen FC. In Vitro Impact of Fluconazole on Oral Microbial Communities, Bacterial Growth, and Biofilm Formation. Antibiotics (Basel) 2023; 12:1433. [PMID: 37760729 PMCID: PMC10525723 DOI: 10.3390/antibiotics12091433] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2023] [Revised: 08/30/2023] [Accepted: 09/02/2023] [Indexed: 09/29/2023] Open
Abstract
Antifungal agents are widely used to specifically eliminate infections by fungal pathogens. However, the specificity of antifungal agents has been challenged by a few studies demonstrating antibacterial inhibitory effects against Mycobacteria and Streptomyces species. Here, we evaluated for the first time the potential effect of fluconazole, the most clinically used antifungal agent, on a human oral microbiota biofilm model. The results showed that biofilm viability on blood and mitis salivarius agar media was increased over time in the presence of fluconazole at clinically relevant concentrations, despite a reduction in biomass. Targeted PCR revealed a higher abundance of Veillonella atypica, Veillonella dispar, and Lactobacillus spp. in the fluconazole-treated samples compared to the control, while Fusobacterium nucleatum was reduced and Streptococcus spp were not significantly affected. Further, we tested the potential impact of fluconazole using single-species models. Our results, using Streptococcus mutans and Streptococcus mitis luciferase reporters, showed that S. mutans planktonic growth was not significantly affected by fluconazole, whereas for S. mitis, planktonic growth, but not biofilm viability, was inhibited at the highest concentration. Fluconazole's effects on S. mitis biofilm biomass were concentration and time dependent. Exposure for 48 h to the highest concentration of fluconazole was associated with S. mitis biofilms with the most increased biomass. Potential growth inhibitory effects were further tested using four non-streptococcal species. Among these, the planktonic growth of both Escherichia coli and Granulicatella adiacens was inhibited by fluconazole. The data indicate bacterial responses to fluconazole that extend to a broader range of bacterial species than previously anticipated from the literature, with the potential to disturb biofilm communities.
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Affiliation(s)
- Louise Morais Dornelas-Figueira
- Department of Prosthodontics and Periodontology, Piracicaba Dental School, University of Campinas, Piracicaba 13414-903, SP, Brazil
- Institute of Oral Biology, Faculty of Dentistry, University of Oslo, 0372 Oslo, Norway
| | - Antônio Pedro Ricomini Filho
- Department of Physiological Sciences, Piracicaba Dental School, University of Campinas, Piracicaba 13414-903, SP, Brazil
| | - Roger Junges
- Institute of Oral Biology, Faculty of Dentistry, University of Oslo, 0372 Oslo, Norway
| | - Heidi Aarø Åmdal
- Institute of Oral Biology, Faculty of Dentistry, University of Oslo, 0372 Oslo, Norway
| | - Altair Antoninha Del Bel Cury
- Department of Prosthodontics and Periodontology, Piracicaba Dental School, University of Campinas, Piracicaba 13414-903, SP, Brazil
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Bibek GC, Zhou P, Naha A, Gu J, Wu C. Development of a Xylose-Inducible Promoter and Riboswitch Combination System for Manipulating Gene Expression in Fusobacterium nucleatum. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.04.24.538132. [PMID: 37163003 PMCID: PMC10168284 DOI: 10.1101/2023.04.24.538132] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
Abstract
Inducible gene expression systems are important for studying bacterial gene function, yet most exhibit leakage. In this study, we engineered a leakage-free hybrid system for precise gene expression controls in Fusobacterium nucleatum by integrating the xylose-inducible expression system with the theophylline-responsive riboswitch. This innovative method enables concurrent control of target gene expression at both transcription and translation initiation levels. Using luciferase and the indole-producing enzyme tryptophanase (TnaA) as reporters, we demonstrated that the hybrid system displays virtually no observable signal in the absence of inducers. We employed this system to express FtsX, a protein related to fusobacterial cytokinesis, in an ftsX mutant strain, unveiling a dose-dependent manner in FtsX production. Without inducers, cells form long filaments, while increasing FtsX levels by increasing inducers concentrations led to a gradual reduction in cell length until normal morphology was restored. Crucially, this system facilitated essential gene investigation, identifying the signal peptidase lepB gene as vital for F. nucleatum . LepB's essentiality stems from depletion, affecting outer membrane biogenesis and cell division. This novel hybrid system holds the potential for advancing research on essential genes and accurate gene regulation in F. nucleatum .
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Nagasawa R, Nomura N, Obana N. Identification of a Novel Gene Involved in Cell-to-cell Communication-induced Cell Death and eDNA Production in Streptococcus mutans. Microbes Environ 2023; 38:n/a. [PMID: 37302844 DOI: 10.1264/jsme2.me22085] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/13/2023] Open
Abstract
Streptococcus mutans is a major caries-causing bacterium that forms firmly attached biofilms on tooth surfaces. Biofilm formation by S. mutans consists of polysaccharide-dependent and polysaccharide-independent processes. Among polysaccharide-independent processes, extracellular DNA (eDNA) mediates the initial attachment of cells to surfaces. We previously reported that the secreted peptide signal, competence-stimulating peptide (CSP) induced cell death in a subpopulation of cells, leading to autolysis-mediated eDNA release. The autolysin gene lytF, the expression of which is stimulated by CSP, has been shown to mediate CSP-dependent cell death, while cell death was not entirely abolished in the lytF deletion mutant, indicating the involvement of other factors. To identify novel genes involved in CSP-dependent cell death, we herein compared transcriptomes between live and dead cells derived from an isogenic population. The results obtained revealed the accumulation of several mRNAs in dead cells. The deletion of SMU_1553c, a putative bacteriocin gene, resulted in significant reductions in CSP-induced cell death and eDNA production levels from those in the parental strain. Moreover, in the double mutant strain of lytF and SMU_1553c, cell death and eDNA production in response to synthetic CSP were completely abolished under both planktonic and biofilm conditions. These results indicate that SMU_1553c is a novel cell death-related factor that contributes to CSP-dependent cell death and eDNA production.
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Affiliation(s)
- Ryo Nagasawa
- Graduate School of Life and Environmental Sciences, University of Tsukuba
| | - Nobuhiko Nomura
- Faculty of Life and Environmental Sciences, University of Tsukuba
- Microbiology Research Center for Sustainability, University of Tsukuba
| | - Nozomu Obana
- Microbiology Research Center for Sustainability, University of Tsukuba
- Faculty of Medicine, Transborder Medical Research Center, University of Tsukuba
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Nima G, Harth-Chu E, Hiers RD, Pecorari VGA, Dyer DW, Khajotia SS, Giannini M, Florez FLE. Antibacterial efficacy of non-thermal atmospheric plasma against Streptococcus mutans biofilm grown on the surfaces of restorative resin composites. Sci Rep 2021; 11:23800. [PMID: 34893687 PMCID: PMC8664839 DOI: 10.1038/s41598-021-03192-0] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2021] [Accepted: 10/28/2021] [Indexed: 01/11/2023] Open
Abstract
The aim of this study was to evaluate the antimicrobial efficacy of non-thermal atmospheric plasma (NTAP) against Streptococcus mutans biofilms. Resin discs were fabricated, wet-polished, UV sterilized, and immersed in water for monomer extraction (37 °C, 24 h). Biofilms of bioluminescent S. mutans strain JM10 was grown on resin discs in anaerobic conditions for (37 °C, 24 h). Discs were divided into seven groups: control (CON), 2% chlorhexidine (CHX), only argon gas 150 s (ARG) and four NTAP treatments (30 s, 90 s, 120 s, 150 s). NTAP was applied using a plasma jet device. After treatment, biofilms were analyzed through the counting of viable colonies (CFU), bioluminescence assay (BL), scanning electron microscopy (SEM), and polymerase chain reaction (PCR). All NTAP-treated biofilm yielded a significant CFU reduction when compared to ARG and CON. BL values showed that NTAP treatment for 90 s, 120 s or 150 s resulted in statistically significantly lower metabolic activity when compared to the other groups. CHX displayed the lowest means of CFU and BL. SEM showed significant morphological changes in NTAP-treated biofilm. PCR indicated damage to the DNA structure after NTAP treatment. NTAP treatment was effective in lowering the viability and metabolism of S. mutans in a time-dependent manner, suggesting its use as an intraoral surface-decontamination strategy.
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Affiliation(s)
- Gabriel Nima
- Department of Restorative Dentistry, Dental Materials Division, Piracicaba Dental School, State University of Campinas, Piracicaba, SP, Brazil.
| | - Erika Harth-Chu
- Department of Oral Diagnosis, Piracicaba Dental School, State University of Campinas, Piracicaba, SP, Brazil
| | - Rochelle Denise Hiers
- Department of Restorative Sciences, Division of Dental Biomaterials, College of Dentistry, The University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA
| | | | - David W Dyer
- Department of Microbiology and Immunology, College of Medicine, The University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA
| | - Sharukh Soli Khajotia
- Department of Restorative Sciences, Division of Dental Biomaterials, College of Dentistry, The University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA
| | - Marcelo Giannini
- Department of Restorative Dentistry, Operative Dentistry Division, Piracicaba Dental School, State University of Campinas, Piracicaba, SP, Brazil
| | - Fernando Luis Esteban Florez
- Department of Restorative Sciences, Division of Dental Biomaterials, College of Dentistry, The University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA
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Wu M, Huang S, Du J, Jiang S, Cai Z, Zhan L, Huang X. Role of D-alanylation of Streptococcus mutans lipoteichoic acid in interspecies competitiveness. Mol Oral Microbiol 2021; 36:233-242. [PMID: 33977670 DOI: 10.1111/omi.12344] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/25/2020] [Revised: 04/24/2021] [Accepted: 04/26/2021] [Indexed: 11/28/2022]
Abstract
BACKGROUND The D-alanylation of lipoteichoic acid (LTA) is essential for the physiological metabolism of Streptococcus mutans (S. mutans). This study was designed to investigate the influence of D-alanylation of LTA on interspecies competitiveness of S. mutans. METHODS The process of D-alanylation was blocked by the inactivation of dltC. Agar competition assays, conditioned medium assays, and qRT-PCR were used to evaluate the production of antimicrobial compounds in S. mutans mutant. Dual-species biofilm was formed to investigate the competitiveness of S. mutans mutant cocultured with S. sanguinis or S. gordonii. RESULTS S. mutans mutant could not produce antimicrobial compounds efficiently when cocultured with commensal bacteria (*p < 0.05). The mutant showed compromised competitiveness in dual-species biofilms. The ratio of the mutant in dual-species biofilms decreased, and the terminal pH of the culture medium in mutant groups (mutant+S. sanguinis/S. gordonii) was higher than that in wild-type groups (*p < 0.05). Scanning electron microscope (SEM) showed weaker demineralization of enamel treated with dual-species biofilms consisting of mutant and commensal bacteria. CONCLUSION D-Alanylation is involved in interspecies competitiveness of S. mutans within oral biofilm by regulating mutacins and lactic acid production, which may modulate the profiles of dental biofilms. Results provide new insights into dental caries prevention and treatment.
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Affiliation(s)
- Minjing Wu
- Fujian Key Laboratory of Oral Diseases &, Fujian Provincial Engineering Research Center of Oral Biomaterial & Stomatological Key lab of Fujian College and University, School and Hospital of Stomatology, Fujian Medical University, Fuzhou, China.,Stomatological Hospital, Southern Medical University, Guangzhou, China
| | - Shan Huang
- Fujian Key Laboratory of Oral Diseases &, Fujian Provincial Engineering Research Center of Oral Biomaterial & Stomatological Key lab of Fujian College and University, School and Hospital of Stomatology, Fujian Medical University, Fuzhou, China
| | - Jingyun Du
- Fujian Key Laboratory of Oral Diseases &, Fujian Provincial Engineering Research Center of Oral Biomaterial & Stomatological Key lab of Fujian College and University, School and Hospital of Stomatology, Fujian Medical University, Fuzhou, China
| | - Shan Jiang
- School of Stomatology, Shenzhen University Health Science Center, Shenzhen, China
| | - Zhiyu Cai
- Department of Stomatology, Fujian Medical University Union Hospital, Fuzhou, China
| | - Ling Zhan
- Division of Pediatric Dentistry, Department of Orofacial Sciences, Department of Preventive and Restorative Dental Sciences, University of California, San Francisco, CA, USA
| | - Xiaojing Huang
- Fujian Key Laboratory of Oral Diseases &, Fujian Provincial Engineering Research Center of Oral Biomaterial & Stomatological Key lab of Fujian College and University, School and Hospital of Stomatology, Fujian Medical University, Fuzhou, China
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Schneider BJ, Hiers RD, Currier GF, Kadioglu O, Johnston SE, Zhao YD, Esteban Florez FL, Khajotia SS. Assessment of Streptococcus mutans biofilms on orthodontic adhesives over 7 days. Am J Orthod Dentofacial Orthop 2021; 160:50-57. [PMID: 34090735 DOI: 10.1016/j.ajodo.2020.03.026] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2019] [Revised: 03/01/2020] [Accepted: 03/01/2020] [Indexed: 11/16/2022]
Abstract
INTRODUCTION The purpose of this study was to compare the metabolism of Streptococcus mutans biofilms after 1-7 days of growth on different orthodontic adhesives. METHODS Specimens of 6 commercial orthodontic adhesives were fabricated in custom-made molds and polymerized using a light-emitting diode light-curing unit. Bioluminescent S mutans (UA159:JM10) biofilms were grown on ultraviolet-sterilized specimens for 1, 3, 5, and 7 days (n = 18 biofilms/d/product) in anaerobic conditions at 37°C. The metabolism of biofilms (relative luminescence unit [RLU]) was measured 0, 2, 4, and 6 minutes after exposure to D-luciferin solution using a microplate reader. A linear mixed-effects model was used to analyze the logarithm of RLU (log RLU). The model included fixed effects of products, days, and minutes. Tukey-Kramer post-hoc tests were then performed on the significant predictors of log RLU (α = 0.05). RESULTS Days (P <0.0001) and minutes (P <0.0001) were independent predictors of log RLU, but the products were not (P = 0.5869). After adjusting for minutes, the log RLU was analyzed with a post-hoc test, and all differences between days were significant with the exceptions of day 3 from day 5 (P = 0.0731) and day 5 from day 7 (P = 0.8802). After adjusting for day, log RLU was analyzed with a post-hoc test and all differences in minutes were significant. CONCLUSIONS No significant differences in the metabolism of S mutans biofilms were observed among the 6 orthodontic adhesives. Biofilms that were grown for 3 days demonstrated the highest levels of biofilm metabolism as evidenced by higher mean log RLU values relative to 1, 5, and 7-day growth durations.
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Affiliation(s)
- Benjamin J Schneider
- Division of Orthodontics, Department of Developmental Sciences, College of Dentistry, University of Oklahoma Health Sciences Center, Oklahoma City, Okla
| | - Rochelle D Hiers
- Division of Dental Biomaterials, Department of Restorative Sciences, College of Dentistry, University of Oklahoma Health Sciences Center, Oklahoma City, Okla
| | - G Frans Currier
- Division of Orthodontics, Department of Developmental Sciences, College of Dentistry, University of Oklahoma Health Sciences Center, Oklahoma City, Okla
| | - Onur Kadioglu
- Division of Orthodontics, Department of Developmental Sciences, College of Dentistry, University of Oklahoma Health Sciences Center, Oklahoma City, Okla
| | - Sarah E Johnston
- Department of Biostatistics and Epidemiology, Hudson College of Public Health, University of Oklahoma Health Sciences Center, Oklahoma City, Okla
| | - Yan D Zhao
- Department of Biostatistics and Epidemiology, Hudson College of Public Health, University of Oklahoma Health Sciences Center, Oklahoma City, Okla
| | - Fernando L Esteban Florez
- Division of Dental Biomaterials, Department of Restorative Sciences, College of Dentistry, University of Oklahoma Health Sciences Center, Oklahoma City, Okla
| | - Sharukh S Khajotia
- Division of Dental Biomaterials, Department of Restorative Sciences, College of Dentistry, University of Oklahoma Health Sciences Center, Oklahoma City, Okla.
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Competence-Stimulating-Peptide-Dependent Localized Cell Death and Extracellular DNA Production in Streptococcus mutans Biofilms. Appl Environ Microbiol 2020; 86:AEM.02080-20. [PMID: 32948520 DOI: 10.1128/aem.02080-20] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2020] [Accepted: 09/14/2020] [Indexed: 02/06/2023] Open
Abstract
Extracellular DNA (eDNA) is a biofilm component that contributes to the formation and structural stability of biofilms. Streptococcus mutans, a major cariogenic bacterium, induces eDNA-dependent biofilm formation under specific conditions. Since cell death can result in the release and accumulation of DNA, the dead cells in biofilms are a source of eDNA. However, it remains unknown how eDNA is released from dead cells and is localized within S. mutans biofilms. We focused on cell death induced by the extracellular signaling peptide called competence-stimulating peptide (CSP). We demonstrate that nucleic acid release into the extracellular environment occurs in a subpopulation of dead cells. eDNA production induced by CSP was highly dependent on the lytF gene, which encodes an autolysin. Although lytF expression was induced bimodally by CSP, lytF-expressing cells further divided into surviving cells and eDNA-producing dead cells. Moreover, we found that lytF-expressing cells were abundant near the bottom of the biofilm, even when all cells in the biofilm received the CSP signal. Dead cells and eDNA were also abundantly present near the bottom of the biofilm. The number of lytF-expressing cells in biofilms was significantly higher than that in planktonic cultures, which suggests that adhesion to the substratum surface is important for the induction of lytF expression. The deletion of lytF resulted in reduced adherence to a polystyrene surface. These results suggest that lytF expression and eDNA production induced near the bottom of the biofilm contribute to a firmly attached and structurally stable biofilm.IMPORTANCE Bacterial communities encased by self-produced extracellular polymeric substances (EPSs), known as biofilms, have a wide influence on human health and environmental problems. The importance of biofilm research has increased, as biofilms are the preferred bacterial lifestyle in nature. Furthermore, in recent years it has been noted that the contribution of phenotypic heterogeneity within biofilms requires analysis at the single-cell or subpopulation level to understand bacterial life strategies. In Streptococcus mutans, a cariogenic bacterium, extracellular DNA (eDNA) contributes to biofilm formation. However, it remains unclear how and where the cells produce eDNA within the biofilm. We focused on LytF, an autolysin that is induced by extracellular peptide signals. We used single-cell level imaging techniques to analyze lytF expression in the biofilm population. Here, we show that S. mutans generates eDNA by inducing lytF expression near the bottom of the biofilm, thereby enhancing biofilm adhesion and structural stability.
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Fugolin APP, Navarro O, Logan MG, Huynh V, França CM, Ferracane JL, Pfeifer CS. Synthesis of di- and triacrylamides with tertiary amine cores and their evaluation as monomers in dental adhesive interfaces. Acta Biomater 2020; 115:148-159. [PMID: 32853802 DOI: 10.1016/j.actbio.2020.08.026] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2020] [Revised: 07/24/2020] [Accepted: 08/14/2020] [Indexed: 01/13/2023]
Abstract
PURPOSE/AIM In an attempt to increase the service life of dental adhesive interfaces, more hydrolytically and enzymatically-stable methacrylate alternatives, such as methacrylamides, have been proposed. The aim of this study was to investigate polymerization behavior, as well as mechanical and biological properties of experimental adhesives containing multi-functional acrylamides. MATERIALS AND METHODS Multi-functional acrylamides (N,N-Bis[(3-methylaminoacryl)propyl]methylamine - BMAAPMA, Tris[(2-methylaminoacryl)ethyl]amine - TMAAEA, N,N'-bis(acrylamido) 1,4-diazepane - BAADA, N,N-Diethyl-1,3-bis(acrylamido)propane - DEBAAP) or HEMA (2-Hydroxyethyl methacrylate - control) were added at 40 wt% to UDMA. 0.2 wt% DMPA and 0.4 wt% DPI-PF6 were used as initiators. Polymerization kinetics was followed in real-time in near-IR during photoactivation (320-500 nm, at 630 mW/cm2). Water sorption/solubility and flexural strength/modulus were measured according to ISO 4049. 1H NMR was used to assess monomer degradation kinetics. MTT assay was used to assess cytotoxicity against OD-21 and DPSC cells. Biofilm formation and adhesion were assessed by Luciferase Assay and Impingement technique, respectively. Solvated adhesives (40 vol% ethanol) were used to test interfacial adhesion strength. The results were analyzed by ANOVA/Tukey's test (α = 0.05). RESULTS In general, the pure methacrylate mixture had higher rate of polymerization (Rpmax), degree of conversion (DC) at Rpmax, and final DC than the acrylamides. Flexural properties after water storage decreased between 11 and 65%, more markedly for acrylamides. Interfacial bond strength was greater and more stable long-term for the newly synthesized acrylamide formulations (less than 4% reduction at 6 months) compared to the methacrylate experimental control (42% reduction at 6 months). HEMA degraded by almost 90%, while the acrylamides showed no degradation in acidic conditions. Cytotoxicity and biofilm formation, in general, were similar for all groups. CONCLUSIONS Despite demonstrating high water sorption, the acrylamide-containing materials had similar mechanical and biological properties and enhanced interfacial bond strength stability compared to the methacrylate control.
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Affiliation(s)
- A P P Fugolin
- Biomaterials and Biomechanics, Department of Restorative Dentistry, Oregon Health & Science University, Portland OR 97239, USA
| | - Oscar Navarro
- Biomaterials and Biomechanics, Department of Restorative Dentistry, Oregon Health & Science University, Portland OR 97239, USA
| | - Matthew G Logan
- Biomaterials and Biomechanics, Department of Restorative Dentistry, Oregon Health & Science University, Portland OR 97239, USA
| | - Vincent Huynh
- Biomaterials and Biomechanics, Department of Restorative Dentistry, Oregon Health & Science University, Portland OR 97239, USA
| | - Cristiane M França
- Biomaterials and Biomechanics, Department of Restorative Dentistry, Oregon Health & Science University, Portland OR 97239, USA
| | - Jack L Ferracane
- Biomaterials and Biomechanics, Department of Restorative Dentistry, Oregon Health & Science University, Portland OR 97239, USA
| | - Carmem S Pfeifer
- Biomaterials and Biomechanics, Department of Restorative Dentistry, Oregon Health & Science University, Portland OR 97239, USA.
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12
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Potential Risk of Spreading Resistance Genes within Extracellular-DNA-Dependent Biofilms of Streptococcus mutans in Response to Cell Envelope Stress Induced by Sub-MICs of Bacitracin. Appl Environ Microbiol 2020; 86:AEM.00770-20. [PMID: 32532873 DOI: 10.1128/aem.00770-20] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2020] [Accepted: 06/08/2020] [Indexed: 02/07/2023] Open
Abstract
Antibiotics are used to treat or prevent some types of bacterial infection. The inappropriate use of antibiotics unnecessarily promotes antibiotic resistance and increases resistant bacteria, and controlling these bacteria is difficult. While the emergence of drug-resistant bacteria is a serious problem, the behavior of drug-resistant bacteria is not fully understood. In this study, we investigated the behavior of Streptococcus mutans, a major etiological agent of dental caries that is resistant to bacitracin, which is a cell wall-targeting antibiotic, and focused on biofilm formation in the presence of bacitracin. S. mutans UA159 most strongly induced extracellular DNA (eDNA)-dependent biofilm formation in the presence of bacitracin at 1/8× MIC. The ΔmbrC and ΔmbrD mutant strains, which lack bacitracin resistance, also formed biofilms in the presence of bacitracin at 1/2× MIC. This difference between the wild type and the mutants was caused by the induction of atlA expression in the mid-log phase. We also revealed that certain rgp genes involved in the synthesis of rhamnose-glucose polysaccharide related to cell wall synthesis were downregulated by bacitracin. In addition, glucosyltransferase-I was also involved in eDNA-dependent biofilm formation. The biofilm led to increased transformation efficiencies and promoted horizontal gene transfer. Biofilms were also induced by ampicillin and vancomycin, antibiotics targeting cell wall synthesis, suggesting that cell envelope stress triggers biofilm formation. Therefore, the expression of the atlA and rgp genes is regulated by S. mutans, which forms eDNA-dependent biofilms, promoting horizontal gene transfer in response to cell envelope stress induced by sub-MICs of antibiotics.IMPORTANCE Antibiotics have been reported to induce biofilm formation in many bacteria at subinhibitory concentrations. Accordingly, it is conceivable that the MIC against drug-sensitive bacteria may promote biofilm formation of resistant bacteria. Since drug-resistant bacteria have spread, it is important to understand the behavior of resistant bacteria. Streptococcus mutans is bacitracin resistant, and the 1/8× MIC of bacitracin, which is a cell wall-targeted antibiotic, induced eDNA-dependent biofilm formation. The ΔmbrC and ΔmbrD strains, which are not resistant to bacitracin, also formed biofilms in the presence of bacitracin at 1/2× MIC, and biofilms of both the wild type and mutants promoted horizontal gene transfer. Another cell wall-targeted antibiotic, vancomycin, showed effects on biofilms and gene transfer similar to those of bacitracin. Thus, treatment with cell wall-targeted antibiotics may promote the spread of drug-resistant genes in biofilms. Therefore, the behavior of resistant bacteria in the presence of antibiotics at sub-MICs should be investigated when using antibiotics.
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Fugolin AP, de Paula AB, Dobson A, Huynh V, Consani R, Ferracane JL, Pfeifer CS. Alternative monomer for BisGMA-free resin composites formulations. Dent Mater 2020; 36:884-892. [PMID: 32402514 PMCID: PMC7305961 DOI: 10.1016/j.dental.2020.04.009] [Citation(s) in RCA: 33] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2019] [Revised: 01/24/2020] [Accepted: 04/20/2020] [Indexed: 02/04/2023]
Abstract
OBJECTIVE Water sorption, high volumetric shrinkage, polymerization stress, and potential estrogenic effects triggered by leached compounds are some of the major concerns related to BisGMA-TEGDMA co-monomer systems used in dental composites. These deficiencies call for the development of alternative organic matrices in order to maximize the clinical lifespan of resin composite dental restorations. This study proposes BisGMA-free systems based on the combination of UDMA and a newly synthesized diurethane dimethacrylate, and evaluates key mechanical and physical properties of the resulting materials. METHODS 2EMATE-BDI (2-hydroxy-1-ethyl methacrylate) was synthesized by the reaction between 2-hydroxy-1-ethyl methacrylate with a difunctional isocyanate (1.3-bis (1- isocyanato-1-methylethylbenzene) - BDI). The compound was copolymerized with UDMA (urethane dimethacrylate) at 40 and 60wt%. UDMA copolymerizations with 40 and 60wt% TEGDMA (triethylene glycol dimethacrylate) were tested as controls, as well as a formulation based in BisGMA (bisphenol A-glycidyl methacrylate)-TEGDMA 60:40% (BT). The organic matrices were made polymerizable by the addition of DMPA (2.2-dimethoxyphenoxy acetophenone) and DPI-PF6 (diphenyliodonium hexafluorophosphate) at 0.2 and 0.4wt%, respectively. Formulations were tested as composite with the addition of 70wt% inorganic content consisting of barium borosilicate glass (0.7μm) and fumed silica mixed in 95 and 5wt%, respectively. All photocuring procedures were carried out by a mercury arc lamp filtered to 320-500nm at 800mW/cm2. The experimental resin composites were tested for kinetics of polymerization and polymerization stress in real time. Flexural strength, elastic modulus, water sorption, and solubility were assessed according to ISO 4049. Biofilm formation was analyzed after 24h by luciferase assay. Data were statistically analyzed by one-way ANOVA and Tukey's test (α≤0.05). RESULTS In general, the addition of 2EMATE-BDI into the formulations decreased the maximum rate of polymerization (RPMAX), the degree of conversion at RPMAX (DC at RPMAX), and the final degree of conversion (final DC). However, these reductions did not compromise mechanical properties, which were comparable to the BT controls, especially after 7-day water incubation. The incorporation of 60wt% 2EMATE-BDI reduced water sorption of the composite. 2EMATE-BDI containing formulations showed reduction in polymerization stress of 30% and 50% in comparison to BT control and TEGDMA copolymerizations, respectively. Biofilm formation was similar among the tested groups. SIGNIFICANCE The use of the newly synthesized diurethane dimethacrylate as co-monomer in dental resin composite formulations seems to be a promising option to develop polymers with low-shrinkage and potentially decreased water degradation.
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Affiliation(s)
- Ana P Fugolin
- Department of Restorative Dentistry/Division of Biomaterials and Biomechanics, 2730 SW Moody Avenue, Portland, OR 97201, United States
| | - Andreia B de Paula
- Department of Restorative Dentistry/Division of Biomaterials and Biomechanics, 2730 SW Moody Avenue, Portland, OR 97201, United States
| | - Adam Dobson
- Department of Restorative Dentistry/Division of Biomaterials and Biomechanics, 2730 SW Moody Avenue, Portland, OR 97201, United States
| | - Vincent Huynh
- Department of Restorative Dentistry/Division of Biomaterials and Biomechanics, 2730 SW Moody Avenue, Portland, OR 97201, United States
| | - Rafael Consani
- Department of Restorative Dentistry/Division of Biomaterials and Biomechanics, 2730 SW Moody Avenue, Portland, OR 97201, United States
| | - Jack L Ferracane
- Department of Restorative Dentistry/Division of Biomaterials and Biomechanics, 2730 SW Moody Avenue, Portland, OR 97201, United States
| | - Carmem S Pfeifer
- Department of Restorative Dentistry/Division of Biomaterials and Biomechanics, 2730 SW Moody Avenue, Portland, OR 97201, United States.
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14
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Bienek DR, Giuseppetti AA, Okeke UC, Frukhtbeyn SA, Dupree PJ, Khajotia SS, Esteban Florez FL, Hiers RD, Skrtic D. Antimicrobial, biocompatibility, and physicochemical properties of novel adhesive methacrylate dental monomers. J BIOACT COMPAT POL 2020. [DOI: 10.1177/0883911520911660] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
For the advancement of Class V restoratives, our goal was to evaluate the physicochemical and mechanical properties, antimicrobial functionality, and cytotoxic potential of novel antimicrobial copolymers. 5-Carboxy-N-(2-(methacryloyloxy)ethyl)-N,N-dimethylpentan-1-aminium bromide (AMadh1) and 10-carboxy-N-(2-(methacryloyloxy)ethyl)-N,N-dimethyldecan-1-aminium bromide (AMadh2) were incorporated into light-curable urethane dimethacrylate, polyethylene glycol–extended urethane dimethacrylate, ethyl 2-(hydroxymethyl) acrylate resin (UPE resin). In the AMadhs-UPE resin, the hydrophobic/hydrophilic balance, degree of vinyl conversion, flexural strength, elastic modulus, and shear bond strength were assessed. Antimicrobial properties were measured using Streptococcus mutans (planktonic and biofilm). Cytotoxicity was tested using human gingival fibroblasts and mouse connective tissue fibroblasts (ATCC® CCL-1™) exposed to two-fold serial dilutions (≤10.6 mmol/L AMadh1 or ≤8.8 mmol/L AMadh2). At 10% mass of AMadh, the attained degree of vinyl conversion values (AMadh1 = 90.1% and AMadh2 = 88.5%) were not statistically different from the UPE resin (88.1%). At both AMadh levels, the flexural strength was reduced in a dose-dependent manner. Elastic modulus and contact angle were not significantly affected by AMadh1. Variations in elastic modulus and contact angle were observed with AMadh2; however, this does not disqualify it in future design of Class V restoratives. Compared to UPE resin, AMadh1-UPE and AMadh2-UPE (10% mass) copolymers reduced S. mutans biofilm 4.2- and 1.6-fold, respectively (p ≤ 0.006). In direct contact with human gingival fibroblasts or ATCC CCL-1 cells, at biologically relevant concentrations, the AMadhs did not adversely affect cell viability or their metabolic activity. This effort addresses a significant oral health issue associated with elderly populations. Its successful completion is expected to yield dental restoratives with well-controlled biofunction.
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Affiliation(s)
- Diane R Bienek
- Innovative & Technology Research, ADA Science & Research Institute, LLC, Frederick, MD, USA
| | - Anthony A Giuseppetti
- Innovative & Technology Research, ADA Science & Research Institute, LLC, Frederick, MD, USA
| | - Ugochukwu C Okeke
- Agricultural Research Service, US Department of Agriculture, Washington, DC, USA
| | - Stanislav A Frukhtbeyn
- Innovative & Technology Research, ADA Science & Research Institute, LLC, Frederick, MD, USA
| | - Peter J Dupree
- School of Dentistry, Louisiana State University Health Sciences Center, New Orleans, LA, USA
| | - Sharukh S Khajotia
- College of Dentistry, The University of Oklahoma, Oklahoma City, OK, USA
| | | | - Rochelle D Hiers
- College of Dentistry, The University of Oklahoma, Oklahoma City, OK, USA
| | - Drago Skrtic
- Innovative & Technology Research, ADA Science & Research Institute, LLC, Frederick, MD, USA
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Esteban Florez FL, Hiers RD, Zhao Y, Merritt J, Rondinone AJ, Khajotia SS. Optimization of a real-time high-throughput assay for assessment of Streptococcus mutans metabolism and screening of antibacterial dental adhesives. Dent Mater 2020; 36:353-365. [PMID: 31952798 PMCID: PMC7042092 DOI: 10.1016/j.dental.2019.12.007] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2019] [Revised: 09/17/2019] [Accepted: 12/18/2019] [Indexed: 12/25/2022]
Abstract
Objective. The present work shows the optimization of a high-throughput bioluminescence assay to assess the metabolism of intact Streptococcus mutans biofilms and its utility as a screening method for nanofilled antibacterial dental materials. Methods. The assay was optimized by monitoring changes in bioluminescence mediated by variation of the experimental parameters investigated (growth media and sucrose concentration, inoculum:D-Luciferin ratio, dilution factor, inoculum volume, luminescence wavelength, replicate and luciferase metabolic activity). Confocal microscopy was then used to demonstrate the impact of biofilm growth conditions on the 3-D distribution of extracellular polymeric substance (EPS) within Streptococcus mutans biofilms and its implications as confounding factors in high-throughput studies (HTS). Results. Relative Luminescence Unit (RLU) values from the HTS optimization were analyzed by multivariate ANOVA (α = 0.05) and coefficients of variation, whereas data from 3-D structural parameters and RLU values of biofilms grown on experimental antibacterial dental adhesive resins were analyzed using General Linear Models and Student–Newman–Keuls post hoc tests (α = 0.05). Confocal microscopy demonstrated that biofilm growth conditions significantly influenced the quantity and distribution of EPS within the 3-D structures of the biofilms. An optimized HTS bioluminescence assay was developed and its applicability as a screening method in dentistry was demonstrated using nanofilled experimental antibacterial dental adhesive resins. Significance. The present study is anticipated to positively impact the direction of future biofilm research in dentistry, because it offers fundamental information for the design of metabolic-based assays, increases the current levels of standardization and reproducibility while offering a tool to decrease intra-study variability.
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Affiliation(s)
- Fernando Luis Esteban Florez
- The University of Oklahoma Health Sciences Center, Department of Restorative Sciences, Division of Dental Biomaterials, College of Dentistry, 1201 N. Stonewall Avenue, Oklahoma City, OK, 73117, USA.
| | - Rochelle Denise Hiers
- The University of Oklahoma Health Sciences Center, Department of Restorative Sciences, Division of Dental Biomaterials, College of Dentistry, 1201 N. Stonewall Avenue, Oklahoma City, OK, 73117, USA.
| | - Yan Zhao
- The University of Oklahoma Health Sciences Center, Department of Biostatistics and Epidemiology, College of Public Health, 801 NE 13th Street, Oklahoma City, OK, 73126, USA.
| | - Justin Merritt
- Oregon Health & Science University, Department of Restorative Dentistry, School of Dentistry, MRB424, 3181 SW Sam Jackson Park Rd., Portland, OR, 97239, USA.
| | - Adam Justin Rondinone
- Oak Ridge National Laboratory, Center for Nanophase Materials Sciences, Oak Ridge, TN, 37831, USA.
| | - Sharukh Soli Khajotia
- The University of Oklahoma Health Sciences Center, Department of Restorative Sciences, Division of Dental Biomaterials, College of Dentistry, 1201 N. Stonewall Avenue, Oklahoma City, OK, 73117, USA.
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16
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Bienek DR, Giuseppetti AA, Frukhtbeyn SA, Hiers RD, Esteban Florez FL, Khajotia SS, Skrtic D. Physicochemical, Mechanical, and Antimicrobial Properties of Novel Dental Polymers Containing Quaternary Ammonium and Trimethoxysilyl Functionalities. J Funct Biomater 2019; 11:E1. [PMID: 31861286 PMCID: PMC7151568 DOI: 10.3390/jfb11010001] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2019] [Revised: 12/03/2019] [Accepted: 12/11/2019] [Indexed: 01/15/2023] Open
Abstract
The aims of this study were to evaluate the physicochemical and mechanical properties, antimicrobial (AM) functionality, and cytotoxic potential of novel dental polymers containing quaternary ammonium and trimethoxysilyl functionalities (e.g., N-(2-(methacryloyloxy)ethyl)-N,N-dimethyl-3-(trimethoxysilyl)propan-1-aminium iodide (AMsil1) and N-(2-(methacryloyloxy)ethyl)-N,N-dimethyl-11-(trimethoxysilyl)undecan-1-aminium bromide (AMsil2)). AMsil1 or AMsil2 were incorporated into light-cured (camphorquinone + ethyl-4-N,N-dimethylamino benzoate) urethane dimethacrylate (UDMA)/polyethylene glycol-extended UDMA/ethyl 2-(hydroxymethyl)acrylate (EHMA) resins (hereafter, UPE resin) at 10 or 20 mass %. Cytotoxic potential was assessed by measuring viability and metabolic activity of immortalized mouse connective tissue and human gingival fibroblasts in direct contact with monomers. AMsil-UPE resins were evaluated for wettability by contact angle measurements and degree of vinyl conversion (DVC) by near infra-red spectroscopy analyses. Mechanical property evaluations entailed flexural strength (FS) and elastic modulus (E) testing of copolymer specimens. The AM properties were assessed using Streptococcus mutans (planktonic and biofilm forms) and Porphyromonas gingivalis biofilm. Neither AMsil exhibited significant toxicity in direct contact with cells at biologically relevant concentrations. Addition of AMsils made the UPE resin more hydrophilic. DVC values for the AMsil-UPE copolymers were 2%-31% lower than that attained in the UPE resin control. The mechanical properties (FS and E) of AMsil-UPE specimens were reduced (11%-57%) compared to the control. Compared to UPE resin, AMsil1-UPE and AMsil2-UPE (10% mass) copolymers reduced S. mutans biofilm 4.7- and 1.7-fold, respectively (p ≤ 0.005). Although not statistically different, P. gingivalis biofilm biomass on AMsil1-UPE and AM AMsil2-UPE copolymer disks were lower (71% and 85%, respectively) than that observed with a commercial AM dental material. In conclusion, the AM function of new monomers is not inundated by their toxicity towards cells. Despite the reduction in mechanical properties of the AMsil-UPE copolymers, AMsil2 is a good candidate for incorporation into multifunctional composites due to the favorable overall hydrophilicity of the resins and the satisfactory DVC values attained upon light polymerization of AMsil-containing UDMA/PEG-U/EHMA copolymers.
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Affiliation(s)
- Diane R. Bienek
- ADA Foundation, Research Division, Frederick, MD 21704, USA; (A.A.G.); (S.A.F.); (D.S.)
| | | | | | - Rochelle D. Hiers
- College of Dentistry, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73117, USA; (R.D.H.); (F.L.E.F.); (S.S.K.)
| | - Fernando L. Esteban Florez
- College of Dentistry, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73117, USA; (R.D.H.); (F.L.E.F.); (S.S.K.)
| | - Sharukh S. Khajotia
- College of Dentistry, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73117, USA; (R.D.H.); (F.L.E.F.); (S.S.K.)
| | - Drago Skrtic
- ADA Foundation, Research Division, Frederick, MD 21704, USA; (A.A.G.); (S.A.F.); (D.S.)
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17
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Fugolin AP, Dobson A, Huynh V, Mbiya W, Navarro O, Franca CM, Logan M, Merritt JL, Ferracane JL, Pfeifer CS. Antibacterial, ester-free monomers: Polymerization kinetics, mechanical properties, biocompatibility and anti-biofilm activity. Acta Biomater 2019; 100:132-141. [PMID: 31574321 PMCID: PMC6894497 DOI: 10.1016/j.actbio.2019.09.039] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2019] [Revised: 09/26/2019] [Accepted: 09/26/2019] [Indexed: 01/09/2023]
Abstract
OBJECTIVES Quaternary ammonium (QA) methacrylate monomers have been extensively investigated and demonstrate excellent antibacterial properties. However, the presence of ester bonds makes them prone to degradation in the oral cavity. In this study, ester-free QA monomers based on meth-acrylamides were synthesized and screened for polymerization kinetics, mechanical properties and antibacterial effects. MATERIALS AND METHODS Tertiary quaternary ammonium acrylamides (AM) and methacrylamides (MAM) with alkyl side chain lengths of 9 and 14 carbons (C9 and C14) were synthesized and incorporated at 10 wt% into experimental composites based on BisGMA:TEGDMA (1:1), camphorquinone/ethyl-4-dimethylaminobenzoate (0.2/0.8 wt%) and 70 wt% barium glass fillers. Analogous methacrylate versions (MA) were used as controls. Degree of conversion (DC) and rate of polymerization (RP) during photoactivation (800 mW/cm2) were followed in real-time with near-IR. Flexural Strength (FS) and Modulus (E) were measured on 2 × 2 × 25 mm bars in 3-point bending after 24 h dry storage and 7-day storage in water at 37 °C. Antimicrobial properties and biofilm adhesion (fouling) were evaluated by bioluminescence (Luciferase Assay) and biofilm removal by water spray microjet impingement test, respectively. Cytotoxicity was assessed by MTT assay on dental pulp stem cells (DPSC). Data were analyzed with one-way ANOVA/Tukey's test (α = 0.05). RESULTS DC was similar for all groups tested (∼70%). Both MAMs and C14-AM presented significantly lower RP. Under dry conditions, FS (110-120 MPa) and E (8-9 GPa) were similar for all groups. After water storage, all materials presented FS/E similar to the control, except for C14-AM (for FS) and C14-MAM (for E), which were lower. All C14 versions were strongly antibacterial, decreasing the titer counts of biofilm by more than two orders of magnitude in comparison to the control. C9 monomers did not present significant antibacterial nor antifouling properties. And biofilms had approximately equivalent adhesion on the C9 composites as on the control. Cytotoxicity did not show significant differences between the MA and AM versions and the control group. CONCLUSIONS C14-QA monomers based on methacrylates and meth-acrylamides present strong antibacterial properties, and in general, similar conversion/mechanical properties compared to the methacrylate control. STATEMENT OF SIGNIFICANCE This work demonstrates the viability of methacrylamides and acrylamides as potential components in dental restorative materials with antimicrobial properties. The use of ester-free polymerizable functionalities has the potential of improving the degradation resistance of these materials long-term. The use of (meth)acrylamides did not interfere with the antimicrobial potential of quaternary ammonium-based materials.
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Affiliation(s)
- Ana P Fugolin
- Division of Biomaterials and Biomechanics, Department of Restorative Dentistry, OHSU School of Dentistry, Oregon Health & Science University, 2730 SW Moody Ave, Portland, OR 97201, USA
| | - Adam Dobson
- Division of Biomaterials and Biomechanics, Department of Restorative Dentistry, OHSU School of Dentistry, Oregon Health & Science University, 2730 SW Moody Ave, Portland, OR 97201, USA
| | - Vincent Huynh
- Division of Biomaterials and Biomechanics, Department of Restorative Dentistry, OHSU School of Dentistry, Oregon Health & Science University, 2730 SW Moody Ave, Portland, OR 97201, USA
| | - Wilbes Mbiya
- Division of Biomaterials and Biomechanics, Department of Restorative Dentistry, OHSU School of Dentistry, Oregon Health & Science University, 2730 SW Moody Ave, Portland, OR 97201, USA
| | - Oscar Navarro
- Division of Biomaterials and Biomechanics, Department of Restorative Dentistry, OHSU School of Dentistry, Oregon Health & Science University, 2730 SW Moody Ave, Portland, OR 97201, USA
| | - Cristiane M Franca
- Division of Biomaterials and Biomechanics, Department of Restorative Dentistry, OHSU School of Dentistry, Oregon Health & Science University, 2730 SW Moody Ave, Portland, OR 97201, USA
| | - Matthew Logan
- Division of Biomaterials and Biomechanics, Department of Restorative Dentistry, OHSU School of Dentistry, Oregon Health & Science University, 2730 SW Moody Ave, Portland, OR 97201, USA
| | - Justin L Merritt
- Division of Biomaterials and Biomechanics, Department of Restorative Dentistry, OHSU School of Dentistry, Oregon Health & Science University, 2730 SW Moody Ave, Portland, OR 97201, USA
| | - Jack L Ferracane
- Division of Biomaterials and Biomechanics, Department of Restorative Dentistry, OHSU School of Dentistry, Oregon Health & Science University, 2730 SW Moody Ave, Portland, OR 97201, USA
| | - Carmem S Pfeifer
- Division of Biomaterials and Biomechanics, Department of Restorative Dentistry, OHSU School of Dentistry, Oregon Health & Science University, 2730 SW Moody Ave, Portland, OR 97201, USA.
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18
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Zajdowicz S, Song HB, Baranek A, Bowman CN. Evaluation of biofilm formation on novel copper-catalyzed azide-alkyne cycloaddition (CuAAC)-based resins for dental restoratives. Dent Mater 2019; 34:657-666. [PMID: 29422327 DOI: 10.1016/j.dental.2018.01.011] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2017] [Revised: 12/25/2017] [Accepted: 01/13/2018] [Indexed: 01/08/2023]
Abstract
OBJECTIVE For the past several decades, the resins used in dental restorations have been plagued with numerous problems, including their implication in biofilm formation and secondary caries. The need for alternative resins is critical, and evaluation of biofilm formation on these resins is essential. The aim of this study was to evaluate in vitro biofilm formation on the surface of novel copper(I)-catalyzed azide-alkyne cycloaddition (CuAAC)-based resins and composites. METHODS CuAAC-based resins/composites made from varying azide monomers and different copper concentrations were compared with BisGMA-TEGDMA resins/composites that served as the control. Biofilms were formed using a mono-species model containing a luciferase-expressing strain of Streptococcus mutans. Luciferase activity was measured and the number of viable bacteria was enumerated on biofilms associated with each resin and composite. RESULTS A significant reduction (p<0.05) in luciferase activity, and the number of viable bacteria recovered from biofilms on CuAAC-based resins and composites was observed in comparison to biofilms associated with the BisGMA-TEGDMA controls. SIGNIFICANCE CuAAC-based resins do still allow for the formation of biofilms; however, the statistically significant reduction of growth that was associated with the CuAAC resin may enhance the longevity of restorations that incorporate CuAAC-based materials.
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Affiliation(s)
- Sheryl Zajdowicz
- Department of Biology, Metropolitan State University of Denver, PO Box 173362, Campus Box #53, Denver, CO, 80217, United States.
| | - Han Byul Song
- Department of Chemical and Biological Engineering, University of Colorado Boulder, 596 UCB, Boulder, CO, United States.
| | - Austin Baranek
- Department of Chemical and Biological Engineering, University of Colorado Boulder, 596 UCB, Boulder, CO, United States.
| | - Christopher N Bowman
- Department of Chemical and Biological Engineering, University of Colorado Boulder, 596 UCB, Boulder, CO, United States.
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Esteban Florez FL, Mendonça de Oliveira MR, de Oliveira Júnior OB, Hiers RD, Khajotia SS, Pretel H. Bioluminescence Analysis of Antibacterial Photodynamic Therapy Using Methylene Blue Mediated by Low-Intensity Level Laser Against Cariogenic Biofilms. Photomed Laser Surg 2018; 36:258-265. [DOI: 10.1089/pho.2017.4326] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Affiliation(s)
- Fernando Luis Esteban Florez
- Department of Dental Materials, College of Dentistry, The University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma
| | - Morgana Regina Mendonça de Oliveira
- Departamento de Odontologia Restauradora, Faculdade de Odontologia de Araraquara, Universidade Estadual Paulista “Júlio de Mesquita Filho,” Araraquara, Brazil
| | - Osmir Batista de Oliveira Júnior
- Departamento de Odontologia Restauradora, Faculdade de Odontologia de Araraquara, Universidade Estadual Paulista “Júlio de Mesquita Filho,” Araraquara, Brazil
| | - Rochelle Denise Hiers
- Department of Dental Materials, College of Dentistry, The University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma
| | - Sharukh Soli Khajotia
- Department of Dental Materials, College of Dentistry, The University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma
| | - Hermes Pretel
- Departamento de Odontologia Restauradora, Faculdade de Odontologia de Araraquara, Universidade Estadual Paulista “Júlio de Mesquita Filho,” Araraquara, Brazil
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Li B, Li X, Lin H, Zhou Y. Curcumin as a Promising Antibacterial Agent: Effects on Metabolism and Biofilm Formation in S. mutans. BIOMED RESEARCH INTERNATIONAL 2018; 2018:4508709. [PMID: 29682545 PMCID: PMC5851298 DOI: 10.1155/2018/4508709] [Citation(s) in RCA: 36] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/09/2017] [Revised: 01/16/2018] [Accepted: 01/29/2018] [Indexed: 12/16/2022]
Abstract
Streptococcus mutans (S. mutans) has been proved to be the main aetiological factor in dental caries. Curcumin, a natural product, has been shown to exhibit therapeutic antibacterial activity, suggesting that curcumin may be of clinical interest. The objective of this study is to evaluate the inhibitory effects of curcumin on metabolism and biofilm formation in S. mutans using a vitro biofilm model in an artificial oral environment. S. mutans biofilms were treated with varying concentrations of curcumin. The biofilm metabolism and biofilm biomass were assessed by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide assay and the crystal violet assay. Confocal laser scanning microscopy was used to analyse the composition and extracellular polysaccharide content of S. mutans biofilm after curcumin treatment. The biofilm structure was evaluated using a scanning electron microscope. The gene expression of virulence-related factors was assessed by real-time PCR. The antibiofilm effect of curcumin was compared with that of chlorhexidine. The sessile minimum inhibitory concentration (SMIC50%) of curcumin against S. mutans biofilm was 500 μM. Curcumin reduced the biofilm metabolism from 5 min to 24 h. Curcumin inhibited the quantity of live bacteria and total bacteria in both the short term (5 min) and the long term. Moreover, curcumin decreased the production of extracellular polysaccharide in the short term. The expression of genes related to extracellular polysaccharide synthesis, carbohydrate metabolism, adherence, and the two-component transduction system decreased after curcumin treatment. The chlorhexidine-treated group showed similar results. We speculate that curcumin has the capacity to be developed as an alternative agent with the potential to reduce the pathogenic traits of S. mutans biofilm.
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Affiliation(s)
- Bingchun Li
- Department of Preventive Dentistry, Guanghua School of Stomatology, Sun Yat-sen University, 56 Ling Yuan Road West, Guangzhou 510055, China
- Guangdong Provincial Key Laboratory of Stomatology, Sun Yat-sen University, Guangzhou 510055, China
| | - Xinlong Li
- Department of Preventive Dentistry, Guanghua School of Stomatology, Sun Yat-sen University, 56 Ling Yuan Road West, Guangzhou 510055, China
- Guangdong Provincial Key Laboratory of Stomatology, Sun Yat-sen University, Guangzhou 510055, China
| | - Huancai Lin
- Department of Preventive Dentistry, Guanghua School of Stomatology, Sun Yat-sen University, 56 Ling Yuan Road West, Guangzhou 510055, China
- Guangdong Provincial Key Laboratory of Stomatology, Sun Yat-sen University, Guangzhou 510055, China
| | - Yan Zhou
- Department of Preventive Dentistry, Guanghua School of Stomatology, Sun Yat-sen University, 56 Ling Yuan Road West, Guangzhou 510055, China
- Guangdong Provincial Key Laboratory of Stomatology, Sun Yat-sen University, Guangzhou 510055, China
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Liu N, Chaudhry MT, Xie Z, Kreth J, Merritt J. Identification of New Degrons in Streptococcus mutans Reveals a Novel Strategy for Engineering Targeted, Controllable Proteolysis. Front Microbiol 2017; 8:2572. [PMID: 29312250 PMCID: PMC5742171 DOI: 10.3389/fmicb.2017.02572] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2017] [Accepted: 12/11/2017] [Indexed: 12/20/2022] Open
Abstract
Recently, controllable, targeted proteolysis has emerged as one of the most promising new strategies to study essential genes and otherwise toxic mutations. One of the principal limitations preventing the wider adoption of this approach is due to the lack of easily identifiable species-specific degrons that can be used to trigger the degradation of target proteins. Here, we report new advancements in the targeted proteolysis concept by creating the first prokaryotic N-terminal targeted proteolysis system. We demonstrate how proteins from the LexA-like protein superfamily can be exploited as species-specific reservoirs of N- and/or C-degrons, which are easily identifiable due to their proximity to strictly conserved residues found among LexA-like proteins. Using the LexA-like regulator HdiR of Streptococcus mutans, we identified two separate N-degrons derived from HdiR that confer highly efficient constitutive proteolysis upon target proteins when added as N-terminal peptide tags. Both degrons mediate degradation via AAA+ family housekeeping proteases with one degron primarily targeting FtsH and the other targeting the ClpP-dependent proteases. To modulate degron activity, our approach incorporates a hybrid N-terminal protein tag consisting of the ubiquitin-like protein NEDD8 fused to an HdiR degron. The NEDD8 fusion inhibits degron function until the NEDD8-specific endopeptidase NEDP1 is heterologously expressed to expose the N-degron. By fusing the NEDD8-degron tag onto GFP, luciferase, and the pleiotropic regulator RNase J2, we demonstrate that the N-terminal proteolysis approach exhibits far superior performance compared to the classic transcriptional depletion approach and is similarly applicable for the study of highly toxic mutations.
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Affiliation(s)
- Nan Liu
- Department of Restorative Dentistry, School of Dentistry, Oregon Health and Science University, Portland, OR, United States
| | | | - Zhoujie Xie
- MOE Key Laboratory of Industrial Fermentation Microbiology, College of Biotechnology, Tianjin University of Science and Technology, Tianjin, China
| | - Jens Kreth
- Department of Restorative Dentistry, School of Dentistry, Oregon Health and Science University, Portland, OR, United States
| | - Justin Merritt
- Department of Restorative Dentistry, School of Dentistry, Oregon Health and Science University, Portland, OR, United States
- Department of Molecular Microbiology and Immunology, School of Medicine, Oregon Health and Science University, Portland, OR, United States
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Senpuku H, Yonezawa H, Yoneda S, Suzuki I, Nagasawa R, Narisawa N. SMU.940 regulates dextran-dependent aggregation and biofilm formation in Streptococcus mutans. Mol Oral Microbiol 2017; 33:47-58. [PMID: 28845576 DOI: 10.1111/omi.12196] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/22/2017] [Indexed: 11/30/2022]
Abstract
The oral bacterium Streptococcus mutans is the principal agent in the development of dental caries. Biofilm formation by S. mutans requires bacterial attachment, aggregation, and glucan formation on the tooth surface under sucrose supplementation conditions. Our previous microarray analysis of clinical strains identified 74 genes in S. mutans that were related to biofilm morphology; however, the roles of almost all of these genes in biofilm formation are poorly understood. We investigated the effects of 21 genes randomly selected from our previous study regarding S. mutans biofilm formation, regulation by the complement pathway, and responses to competence-stimulating peptide. Eight competence-stimulating peptide-dependent genes were identified, and their roles in biofilm formation and aggregation were examined by mutational analyses of the S. mutansUA159 strain. Of these eight genes, the inactivation of the putative hemolysin III family SMU.940 gene of S. mutansUA159 promoted rapid dextran-dependent aggregation and biofilm formation in tryptic soy broth without dextrose (TSB) with 0.25% glucose and slightly reduced biofilm formation in TSB with 0.25% sucrose. The SMU.940 mutant showed higher expression of GbpC and gbpC gene than wild-type. GbpC is known to be involved in the dextran-dependent aggregation of S. mutans. An SMU.940-gbpC double mutant strain was constructed in the SMU.940 mutant background. The gbpC mutation completely abolished the dextran-dependent aggregation of the SMU.940 mutant. In addition, the aggregation of the mutant was abrogated by dextranase. These findings suggest that SMU.940 controls GbpC expression, and contributes to the regulation of dextran-dependent aggregation and biofilm formation.
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Affiliation(s)
- Hidenobu Senpuku
- Department of Bacteriology I, National Institute of Infectious Diseases, Shinjuku-ku, Tokyo, Japan
| | - Hideo Yonezawa
- Department of Bacteriology I, National Institute of Infectious Diseases, Shinjuku-ku, Tokyo, Japan.,Department of Infectious Diseases, Kyorin University School of Medicine, Mitaka, Tokyo, Japan
| | - Saori Yoneda
- Department of Bacteriology I, National Institute of Infectious Diseases, Shinjuku-ku, Tokyo, Japan.,Department of Microbiology, Faculty of Medicine, Kagawa University, Takamatsu, Japan
| | - Itaru Suzuki
- Department of Bacteriology I, National Institute of Infectious Diseases, Shinjuku-ku, Tokyo, Japan.,Department of Pediatric Dentistry, Nihon University at Matsudo, Chiba, Japan
| | - Ryo Nagasawa
- Department of Bacteriology I, National Institute of Infectious Diseases, Shinjuku-ku, Tokyo, Japan.,Graduate School of Science and Engineering, Hosei University, Shinjuku-ku, Tokyo, Japan
| | - Naoki Narisawa
- Department of Bacteriology I, National Institute of Infectious Diseases, Shinjuku-ku, Tokyo, Japan.,Department of Food Science and Technology, College of Bioresource Sciences, Nihon University, Fujisawa, Kanagawa, Japan
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Raffinose Induces Biofilm Formation by Streptococcus mutans in Low Concentrations of Sucrose by Increasing Production of Extracellular DNA and Fructan. Appl Environ Microbiol 2017; 83:AEM.00869-17. [PMID: 28526794 DOI: 10.1128/aem.00869-17] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2017] [Accepted: 05/13/2017] [Indexed: 02/06/2023] Open
Abstract
Streptococcus mutans is the primary etiological agent of dental caries and causes tooth decay by forming a firmly attached biofilm on tooth surfaces. Biofilm formation is induced by the presence of sucrose, which is a substrate for the synthesis of extracellular polysaccharides but not in the presence of oligosaccharides. Nonetheless, in this study, we found that raffinose, which is an oligosaccharide with an intestinal regulatory function and antiallergic effect, induced biofilm formation by S. mutans in a mixed culture with sucrose, which was at concentrations less than those required to induce biofilm formation directly. We analyzed the possible mechanism behind the small requirement for sucrose for biofilm formation in the presence of raffinose. Our results suggested that sucrose contributed to an increase in bacterial cell surface hydrophobicity and biofilm formation. Next, we examined how the effects of raffinose interacted with the effects of sucrose for biofilm formation. We showed that the presence of raffinose induced fructan synthesis by fructosyltransferase and aggregated extracellular DNA (eDNA, which is probably genomic DNA released from dead cells) into the biofilm. eDNA seemed to be important for biofilm formation, because the degradation of DNA by DNase I resulted in a significant reduction in biofilm formation. When assessing the role of fructan in biofilm formation, we found that fructan enhanced eDNA-dependent cell aggregation. Therefore, our results show that raffinose and sucrose have cooperative effects and that this induction of biofilm formation depends on supportive elements that mainly consist of eDNA and fructan.IMPORTANCE The sucrose-dependent mechanism of biofilm formation in Streptococcus mutans has been studied extensively. Nonetheless, the effects of carbohydrates other than sucrose are inadequately understood. Our findings concerning raffinose advance the understanding of the mechanism underlying the joint effects of sucrose and other carbohydrates on biofilm formation. Since raffinose has been reported to have positive effects on enterobacterial flora, research on the effects of raffinose on the oral flora are required prior to its use as a beneficial sugar for human health. Here, we showed that raffinose induced biofilm formation by S. mutans in low concentrations of sucrose. The induction of biofilm formation generally generates negative effects on the oral flora. Therefore, we believe that this finding will aid in the development of more effective oral care techniques to maintain oral flora health.
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Esteban Florez FL, Hiers RD, Smart K, Kreth J, Qi F, Merritt J, Khajotia SS. Real-time assessment of Streptococcus mutans biofilm metabolism on resin composite. Dent Mater 2016; 32:1263-1269. [PMID: 27515531 DOI: 10.1016/j.dental.2016.07.010] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2016] [Revised: 05/16/2016] [Accepted: 07/19/2016] [Indexed: 11/30/2022]
Abstract
OBJECTIVE The release of unpolymerized monomers and by-products of resin composites influences biofilm growth and confounds the measurement of metabolic activity. Current assays to measure biofilm viability have critical limitations and are typically not performed on relevant substrates. The objective of the present study was to determine the utility of firefly luciferase assay for quantification of the viability of intact biofilms on a resin composite substrate, and correlate the results with a standard method (viable colony counts). METHODS Disk-shaped specimens of a dental resin composite were fabricated, wet-polished, UV-sterilized, and stored in water. Biofilms of Streptococcus mutans (strain UA159 modified by insertion of constitutively expressed firefly luc gene) were grown (1:500 dilution; anaerobic conditions, 24h, 37°C) in two media concentrations (0.35x and 0.65x THY medium supplemented with 0.1% sucrose; n=15/group). An additional group of specimens with biofilms grown in 0.65x+sucrose media was treated with chlorhexidine gluconate solution to serve as the control group. Bioluminescence measurements of non-disrupted biofilms were obtained after addition of d-Luciferin substrate. The adherent biofilms were removed by sonication, and bioluminescence of sonicated bacteria was then measured. Viable colony counts were performed after plating sonicated bacteria on THY agar plates supplemented with spectinomycin. Bioluminescence values and cell counts were correlated using Spearman correlation tests (α=0.05). RESULTS Strong positive correlations between viable colony counts and bioluminescence values, both before- and after-sonication, validated the utility of this assay. SIGNIFICANCE A novel non-disruptive, real-time bioluminescence assay is presented for quantification of intact S. mutans biofilms grown on a resin composite, and potentially on antibacterial materials and other types of dental biomaterials.
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Affiliation(s)
- Fernando Luis Esteban Florez
- Dental Materials, College of Dentistry, University of Oklahoma Health Sciences Center, 1201 N. Stonewall Avenue, Oklahoma City, OK 73117, United States.
| | - Rochelle Denise Hiers
- Dental Materials, College of Dentistry, University of Oklahoma Health Sciences Center, 1201 N. Stonewall Avenue, Oklahoma City, OK 73117, United States.
| | - Kristin Smart
- Dental Materials, College of Dentistry, University of Oklahoma Health Sciences Center, 1201 N. Stonewall Avenue, Oklahoma City, OK 73117, United States.
| | - Jens Kreth
- Microbiology and Immunology, College of Medicine, University of Oklahoma Health Sciences Center, 940 Stanton L. Young Blvd., BMSB 1053, Oklahoma City, OK 73104, United States; Restorative Dentistry, Oregon Health & Science University, MRB424, 3181 SW Sam Jackson Park Rd., Portland, OR 97239, United States.
| | - Fengxia Qi
- Microbiology and Immunology, College of Medicine, University of Oklahoma Health Sciences Center, 940 Stanton L. Young Blvd., BMSB 1053, Oklahoma City, OK 73104, United States.
| | - Justin Merritt
- Restorative Dentistry, Oregon Health & Science University, MRB424, 3181 SW Sam Jackson Park Rd., Portland, OR 97239, United States.
| | - Sharukh Soli Khajotia
- Dental Materials, College of Dentistry, University of Oklahoma Health Sciences Center, 1201 N. Stonewall Avenue, Oklahoma City, OK 73117, United States.
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25
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Merritt J, Senpuku H, Kreth J. Let there be bioluminescence: development of a biophotonic imaging platform for in situ analyses of oral biofilms in animal models. Environ Microbiol 2016; 18:174-90. [PMID: 26119252 PMCID: PMC5050008 DOI: 10.1111/1462-2920.12953] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2015] [Revised: 06/09/2015] [Accepted: 06/10/2015] [Indexed: 12/23/2022]
Abstract
In the current study, we describe a novel biophotonic imaging-based reporter system that is particularly useful for the study of virulence in polymicrobial infections and interspecies interactions within animal models. A suite of luciferase enzymes was compared using three early colonizing species of the human oral flora (Streptococcus mutans, Streptococcus gordonii and Streptococcus sanguinis) to determine the utility of the different reporters for multiplexed imaging studies in vivo. Using the multiplex approach, we were able to track individual species within a dual-species oral infection model in mice with both temporal and spatial resolution. We also demonstrate how biophotonic imaging of multiplexed luciferase reporters could be adapted for real-time quantification of bacterial gene expression in situ. By creating an inducible dual-luciferase expressing reporter strain of S. mutans, we were able to exogenously control and measure expression of nlmAB (encoding the bacteriocin mutacin IV) within mice to assess its importance for the persistence ability of S. mutans in the oral cavity. The imaging system described in the current study circumvents many of the inherent limitations of current animal model systems, which should now make it feasible to test hypotheses that were previously impractical to model.
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Affiliation(s)
- Justin Merritt
- Department of Microbiology and Immunology, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, USA
- College of Dentistry, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, USA
| | - Hidenobu Senpuku
- Department of Bacteriology I, National Institute of Infectious Diseases, 1-23-1, Toyama, Shinjuku-ku, Tokyo 162-8640, Japan
| | - Jens Kreth
- Department of Microbiology and Immunology, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, USA
- College of Dentistry, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, USA
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26
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Arruda Cavalcante TT, Carneiro VA, Neves CC, Sousa Duarte HD, Queiroz Martins MGD, Sousa Arruda FV, Vasconcelos MAD, dos Santos HS, Silva Cunha RMD, Cavada BS, Teixeira EH. A ConA-like lectin isolated from <i>Canavalia maritima</i> seeds alters the expression of genes related to virulence and biofilm formation in <i>Streptococcus mutans</i>. ACTA ACUST UNITED AC 2013. [DOI: 10.4236/abb.2013.412143] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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He Z, Wang Q, Hu Y, Liang J, Jiang Y, Ma R, Tang Z, Huang Z. Use of the quorum sensing inhibitor furanone C-30 to interfere with biofilm formation by Streptococcus mutans and its luxS mutant strain. Int J Antimicrob Agents 2012; 40:30-5. [DOI: 10.1016/j.ijantimicag.2012.03.016] [Citation(s) in RCA: 67] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2012] [Revised: 03/24/2012] [Accepted: 03/28/2012] [Indexed: 12/17/2022]
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Antimicrobial penetration and efficacy in an in vitro oral biofilm model. Antimicrob Agents Chemother 2011; 55:3338-44. [PMID: 21537022 DOI: 10.1128/aac.00206-11] [Citation(s) in RCA: 76] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
The penetration and overall efficacy of six mouthrinse actives was evaluated by using an in vitro flow cell oral biofilm model. The technique involved preloading biofilm cells with a green fluorescent dye that leaked out as the cells were permeabilized by a treatment. The loss of green color, and of biomass, was observed by time-lapse microscopy during 60 min of treatment under continuous flow conditions. The six actives analyzed were ethanol, sodium lauryl sulfate, triclosan, chlorhexidine digluconate (CHX), cetylpyridinium chloride, and nisin. Each of these agents effected loss of green fluorescence throughout biofilm cell clusters, with faster action at the edge of a cell cluster and slower action in the cluster center. The time to reach half of the initial fluorescent intensity at the center of a cell cluster, which can be viewed as a combined penetration and biological action time, ranged from 0.6 to 19 min for the various agents. These times are much longer than the predicted penetration time based on diffusion alone, suggesting that anti-biofilm action was controlled more by the biological action time than by the penetration time of the active. None of the agents tested caused any removal of the biofilm. The extent of fluorescence loss after 1 h of exposure to an active ranged from 87 to 99.5%, with CHX being the most effective. The extent of fluorescence loss in vitro, but not penetration and action time, correlated well with the relative efficacy data from published clinical trials.
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Regulation of ciaXRH operon expression and identification of the CiaR regulon in Streptococcus mutans. J Bacteriol 2010; 192:4669-79. [PMID: 20639331 DOI: 10.1128/jb.00556-10] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The ciaRH operon in Streptococcus mutans contains 3 contiguous genes, ciaXRH. Unlike the CiaRH system in other streptococci, only the ciaH-null mutant displays defective phenotypes, while the ciaR-null mutant behaves like the wild type. The objective of this study was to determine the mechanism of this unusual property. We demonstrate that the ciaH mutation caused a >20-fold increase in ciaR transcript synthesis. A ciaRH double deletion reversed the ciaH phenotype, suggesting that overexpressed ciaR might be responsible for the observed ciaH phenotypes. When ciaR was forced to be overexpressed by a transcriptional fusion to the ldh promoter in the wild-type background, the same ciaH phenotypes were restored, confirming the involvement of overexpressed ciaR in the ciaH phenotypes. The ciaH mutation and ciaR overexpression also caused transcriptional alterations in 100 genes, with 15 genes upregulated >5-fold. Bioinformatics analysis identified a putative CiaR regulon consisting of 8 genes/operons, including the ciaXRH operon itself, all of which were upregulated. In vitro footprinting on 4 of the 8 promoters revealed a protected region of 26 to 28 bp encompassing two direct repeats, NTTAAG-n5-WTTAAG, 10 bp upstream of the -10 region, indicating direct binding of the CiaR protein to these promoters. Taken together, we conclude that overexpressed CiaR, as a result of either ciaH deletion or forced expression from a constitutive promoter, is a mediator in the CiaH-regulated phenotypes.
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30
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Wen ZT, Yates D, Ahn SJ, Burne RA. Biofilm formation and virulence expression by Streptococcus mutans are altered when grown in dual-species model. BMC Microbiol 2010; 10:111. [PMID: 20398271 PMCID: PMC2867949 DOI: 10.1186/1471-2180-10-111] [Citation(s) in RCA: 112] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2009] [Accepted: 04/14/2010] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Microbial cell-cell interactions in the oral flora are believed to play an integral role in the development of dental plaque and ultimately, its pathogenicity. The effects of other species of oral bacteria on biofilm formation and virulence gene expression by Streptococcus mutans, the primary etiologic agent of dental caries, were evaluated using a dual-species biofilm model and RealTime-PCR analysis. RESULTS As compared to mono-species biofilms, biofilm formation by S. mutans was significantly decreased when grown with Streptococcus sanguinis, but was modestly increased when co-cultivated with Lactobacillus casei. Co-cultivation with S. mutans significantly enhanced biofilm formation by Streptococcus oralis and L. casei, as compared to the respective mono-species biofilms. RealTime-PCR analysis showed that expression of spaP (for multi-functional adhesin SpaP, a surface-associated protein that S. mutans uses to bind to the tooth surface in the absence of sucrose), gtfB (for glucosyltransferase B that synthesizes alpha1,6-linked glucan polymers from sucrose and starch carbohydrates) and gbpB (for surface-associated protein GbpB, which binds to the glucan polymers) was decreased significantly when S. mutans were co-cultivated with L. casei. Similar results were also found with expression of spaP and gbpB, but not gtfB, when S. mutans was grown in biofilms with S. oralis. Compared to mono-species biofilms, the expression of luxS in S. mutans co-cultivated with S. oralis or L. casei was also significantly decreased. No significant differences were observed in expression of the selected genes when S. mutans was co-cultivated with S. sanguinis. CONCLUSIONS These results suggest that the presence of specific oral bacteria differentially affects biofilm formation and virulence gene expression by S. mutans.
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Affiliation(s)
- Zezhang T Wen
- Department of Oral and Craniofacial Biology, Louisiana State University Health Sciences Center, New Orleans, LA 70119, USA.
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The hdrRM operon of Streptococcus mutans encodes a novel regulatory system for coordinated competence development and bacteriocin production. J Bacteriol 2010; 192:1844-52. [PMID: 20118256 DOI: 10.1128/jb.01667-09] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
The Streptococcus mutans hdrRM operon encodes a novel two-gene regulatory system induced by high cell density. Previous studies identified hdrM as the only known negative regulator of competence development in S. mutans. In the present study, we demonstrated that the HdrRM system bypasses the prototypical competence gene regulators ComC and ComDE in the transcriptional regulation of the competence-specific sigma factor comX and the late competence genes. Similarly, the HdrRM system can abrogate the requirement for ComE to produce the bacteriocin mutacin IV. To further probe the regulatory mechanism of hdrRM, we created an hdrR overexpression strain and showed that it could reproduce each of the hdrM competence and mutacin phenotypes, indicating that HdrM acts as a negative regulator of HdrR activity. Using a mutacin IV-luciferase reporter, we also demonstrated that the hdrRM system utilizes the same promoter elements recognized by ComE and thus appears to comprise a novel regulatory pathway parallel to ComCDE.
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Li L, He J, Eckert R, Yarbrough D, Lux R, Anderson M, Shi W. Design and characterization of an acid-activated antimicrobial peptide. Chem Biol Drug Des 2009; 75:127-32. [PMID: 19878192 DOI: 10.1111/j.1747-0285.2009.00904.x] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Dental caries is a microbial biofilm infection in which the metabolic activities of plaque bacteria result in a dramatic pH decrease and shift the demineralization/remineralization equilibrium on the tooth surface towards demineralization. In addition to causing a net loss in tooth minerals, creation of an acidic environment favors growth of acid-enduring and acid-generating species, which causes further reduction in the plaque pH. In this study, we developed a prototype antimicrobial peptide capable of achieving high activity exclusively at low environmental pH to target bacterial species like Streptococcus mutans that produce acid and thrive under the low pH conditions detrimental for tooth integrity. The features of clavanin A, a naturally occurring peptide rich in histidine and phenylalanine residues with pH-dependent antimicrobial activity, served as a design basis for these prototype 'acid-activated peptides' (AAPs). Employing the major cariogenic species S. mutans as a model system, the two AAPs characterized in this study exhibited a striking pH-dependent antimicrobial activity, which correlated well with the calculated charge distribution. This type of peptide represents a potential new way to combat dental caries.
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33
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He J, Anderson MH, Shi W, Eckert R. Design and activity of a 'dual-targeted' antimicrobial peptide. Int J Antimicrob Agents 2009; 33:532-7. [PMID: 19188046 DOI: 10.1016/j.ijantimicag.2008.11.013] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2008] [Revised: 11/19/2008] [Accepted: 11/25/2008] [Indexed: 12/24/2022]
Abstract
Numerous reports have indicated the important role of human normal flora in the prevention of microbial pathogenesis and disease. Evidence suggests that infections at mucosal surfaces result from the outgrowth of subpopulations or clusters within a microbial community and are not linked to one pathogenic organism alone. To preserve the protective normal flora whilst treating the majority of infective bacteria in the community, a tuneable therapeutic is necessary that can discriminate between benign bystanders and multiple pathogenic organisms. Here we describe the proof-of-principle for such a multitargeted antimicrobial: a multiple-headed specifically targeted antimicrobial peptide (MH-STAMP). The completed MH-STAMP, M8(KH)-20, displays specific activity against targeted organisms in vitro (Pseudomonas aeruginosa and Streptococcus mutans) and can remove both species from a mixed planktonic culture with little impact against untargeted bacteria. These results demonstrate that a functional, dual-targeted molecule can be constructed from a wide-spectrum antimicrobial peptide precursor.
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Affiliation(s)
- Jian He
- School of Dentistry, University of California, Los Angeles, CA 90095, USA
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Merritt J, Zheng L, Shi W, Qi F. Genetic characterization of the hdrRM operon: a novel high-cell-density-responsive regulator in Streptococcus mutans. Microbiology (Reading) 2007; 153:2765-2773. [PMID: 17660440 DOI: 10.1099/mic.0.2007/007468-0] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Many species of bacteria can adhere to surfaces and grow as sessile communities. The continued accumulation of bacteria can eventually lead to the extremely high-cell-density environment characteristic of many biofilms or cell colonies. This is the normal habitat of the cariogenic species Streptococcus mutans, which normally resides in the high-cell-density, multispecies community commonly referred to as dental plaque. Previous work has demonstrated that the transcription of two separate bacteriocins can be activated by the high-cell-density conditions created through the centrifugation and incubation of cell pellets. In this study, we identified an uncharacterized two-gene operon that was induced >10-fold by conditions of high cell density. The genes of the operon encode a putative transcription regulator and a membrane protein, which were renamed as hdrR and hdrM, respectively. A transcription fusion to the hdrRM operon confirmed its induction by high cell density. Mutation of hdrM abolished bacteriocin production, greatly increased natural competence, reduced the growth rate, and severely affected biofilm formation. Interestingly, no obvious phenotypes were observed from a non-polar mutation of hdrR or mutations affecting the entire operon. These data suggest that the hdrRM operon may constitute a novel regulatory system responsible for mediating a cellular response to a high-cell-density environment.
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Affiliation(s)
- Justin Merritt
- UCLA School of Dentistry, Department of Oral Biology, Los Angeles, CA 90025, USA
| | - Lanyan Zheng
- China Medical University, Department of Microbiology and Parasitology, Shenyang, China
| | - Wenyuan Shi
- UCLA Molecular Biology Institute, Los Angeles, CA 90025, USA
- UCLA School of Dentistry, Department of Oral Biology, Los Angeles, CA 90025, USA
| | - Fengxia Qi
- UCLA School of Dentistry, Department of Oral Biology, Los Angeles, CA 90025, USA
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Chung JH, Park YS, Kim J, Shin GW, Nam MH, Oh MK, Kim CW, Jung GY, Hyun Park J. Parallel analysis of antimicrobial activities in microbial community by SSCP based on CE. Electrophoresis 2007; 28:2416-23. [PMID: 17577886 DOI: 10.1002/elps.200600570] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Conventional antimicrobial activity analyses such as the broth dilution method and disk diffusion test are considerably demanding processes for new antimicrobial agent discovery and sensitive diagnosis of infectious diseases. Here, we developed a new antimicrobial activity analysis system using CE-based SSCP (CE-SSCP) combined with 16S rRNA gene-specific PCR (PCR/CE-SSCP). Using this method, the population change in the microbial community in response to specific antimicrobial agents could be quantified with a high sensitivity and accuracy from a small sample amount. Using a mixture of microorganisms comprising Escherichia coli, Corynebacterium glutamicum, Acinetobacter calcoaceticus, and Staphylococcus aureus as a model system, the linear correlation between the genomic DNA concentrations and peak areas in 16S rRNA gene-specific PCR/CE-SSCP was determined; consequently, quantification of cell concentrations could be demonstrated using this method. Compared to the minimum inhibitory concentration (MIC) values from the conventional broth dilution method, this new system provided almost the same MIC values for popular antimicrobial agents such as kanamycin, spectinomycin, and streptomycin. The results demonstrated that the newly developed method can be a substitute for the conventional antimicrobial analysis method and highlighted its high potential in the areas of new antimicrobial agent discovery and clinical diagnosis.
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Affiliation(s)
- Joo Hee Chung
- Metabolome Analysis Team, Korea Basic Science Institute, Seoul, Korea
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Merritt J, Tsang P, Zheng L, Shi W, Qi F. Construction of a counterselection-based in-frame deletion system for genetic studies of Streptococcus mutans. ACTA ACUST UNITED AC 2007; 22:95-102. [PMID: 17311632 DOI: 10.1111/j.1399-302x.2007.00329.x] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Genetic studies of Streptococcus mutans have benefited greatly from the numerous techniques that have been successfully adapted for use in this organism. One notable exception is the lack of a negative selection system that can be employed for the easy isolation of markerless in-frame deletions. In this study, we report the development of a galK/galactose-based negative selection system in S. mutans for this purpose. This system consists of a recipient strain (IFD140) that contains a deletion in the galKTE operon and a suicide vector (pIFD-Sm) that carries the S. mutans galK open reading frame fused to the constitutive lactate dehydrogenase (ldh) promoter. Using this system we created a markerless in-frame deletion in the beta-galactosidase (lacG) gene within the S. mutans lactose operon. After vector integration, plasmid excision after counterselection appeared to have occurred in 100% of the galactose-resistant colonies and resulted in in-frame deletions in 50% of the screened isolates. Based on the ratio of galactose-resistant cells to total cells, we determined that plasmid excision occurred at a frequency of approximately 1/3000 cells. Furthermore, the simplicity of this system should make it adaptable for use in numerous other gram-positive and gram-negative organisms.
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Affiliation(s)
- J Merritt
- Department of Oral Biology, UCLA School of Dentistry, Los Angeles, CA 90095-1668, USA.
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Tong H, Zhu B, Chen W, Qi F, Shi W, Dong X. Establishing a genetic system for ecological studies of Streptococcus oligofermentans. FEMS Microbiol Lett 2007; 264:213-9. [PMID: 17064375 DOI: 10.1111/j.1574-6968.2006.00453.x] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
Streptococcus oligofermentans is a newly characterized species belonging to the mitis group of oral streptococci. So far no correlation has been demonstrated between S. oligofermentans and dental caries. Furthermore, a reverse correlation has been observed between the number of S. oligofermentans and the number of Streptococcus mutans, a major cariogenic pathogen, in the oral cavity. These properties suggest that S. oligofermentans may have a potential to be used as a 'probiotics' for caries prevention. In this study, we aim to establish a genetic system in S. oligofermentans to further study the biology of this new species. Using homologous regions of the comCDE locus in other streptococci, the comC gene was isolated and sequenced. A synthetic competence-stimulating peptide (CSP) was synthesized and shown to be able to effectively induce competence in S. oligofermentans. This CSP-induced transformation system in S. oligofermentans was used to construct green fluorescent protein (gfp) and luciferase (luc) reporter systems, both of which are driven by the lactate dehydrogenase (ldh) promoter. These reporter systems were further shown to be highly expressed in planktonic and biofilm cells, suggesting that these reporter systems can be used in future ecological studies of S. oligofermentans.
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Affiliation(s)
- Huichun Tong
- State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China
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Eckert R, He J, Yarbrough DK, Qi F, Anderson MH, Shi W. Targeted killing of Streptococcus mutans by a pheromone-guided "smart" antimicrobial peptide. Antimicrob Agents Chemother 2006; 50:3651-7. [PMID: 17060534 PMCID: PMC1635210 DOI: 10.1128/aac.00622-06] [Citation(s) in RCA: 160] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Within the repertoire of antibiotics available to a prescribing clinician, the majority affect a broad range of microorganisms, including the normal flora. The ecological disruption resulting from antibiotic treatment frequently results in secondary infections or other negative clinical consequences. To address this problem, our laboratory has recently developed a new class of pathogen-selective molecules, called specifically (or selectively) targeted antimicrobial peptides (STAMPs), based on the fusion of a species-specific targeting peptide domain with a wide-spectrum antimicrobial peptide domain. In the current study, we focused on achieving targeted killing of Streptococcus mutans, a cavity-causing bacterium that resides in a multispecies microbial community (dental plaque). In particular, we explored the possibility of utilizing a pheromone produced by S. mutans, namely, the competence stimulating peptide (CSP), as a STAMP targeting domain to mediate S. mutans-specific delivery of an antimicrobial peptide domain. We discovered that STAMPs constructed with peptides derived from CSP were potent against S. mutans grown in liquid or biofilm states but did not affect other oral streptococci tested. Further studies showed that an 8-amino-acid region within the CSP sequence is sufficient for targeted delivery of the antimicrobial peptide domain to S. mutans. The STAMPs presented here are capable of eliminating S. mutans from multispecies biofilms without affecting closely related noncariogenic oral streptococci, indicating the potential of these molecules to be developed into "probiotic" antibiotics which could selectively eliminate pathogens while preserving the protective benefits of a healthy normal flora.
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Affiliation(s)
- Randal Eckert
- Department of Microbiology, Immunology, and Molecular Genetics,1 School of Dentistry, University of California, Los Angeles, California 90095, USA
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Merritt J, Kreth J, Shi W, Qi F. LuxS controls bacteriocin production in Streptococcus mutans through a novel regulatory component. Mol Microbiol 2005; 57:960-9. [PMID: 16091037 DOI: 10.1111/j.1365-2958.2005.04733.x] [Citation(s) in RCA: 76] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The oral pathogen Streptococcus mutans employs a variety of mechanisms to maintain a competitive advantage over many other oral bacteria which occupy the same ecological niche. Production of the bacteriocin, mutacin I, is one such mechanism. However, little is known about the regulatory mechanisms associated with mutacin I production. Previous work has demonstrated that the production of mutacin I greatly increased with cell density. In this study, we found that high cell density also triggered high level mutacin I gene transcription. However, this response was abolished upon deletion of luxS. Further analysis using real-time reverse transcription polymerase chain reaction (RT-PCR) demonstrated that in the luxS mutant transcription of both the mutacin I structural gene mutA and the mutacin I transcriptional activator mutR was impaired. Through microarray analysis, a putative transcription repressor annotated as Smu1274 in the Los Alamos National Laboratory Oral Pathogens Sequence Database was identified, which was strongly induced in the luxS mutant. Characterization of Smu1274, which we referred to as irvA, suggested that it may act as an inducible repressor to suppress mutacin I gene expression. A luxS and irvA double mutant regained the ability to produce mutacin I; whereas a constitutive irvA-producing strain was impaired in mutacin I production. These findings reveal a novel regulatory pathway for mutacin I gene expression, which may provide clues to the regulatory mechanisms of other cellular functions regulated by luxS in S. mutans.
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Affiliation(s)
- Justin Merritt
- UCLA Molecular Biology Institute, Los Angeles, CA 90095, USA
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Kreth J, Merritt J, Shi W, Qi F. Competition and coexistence between Streptococcus mutans and Streptococcus sanguinis in the dental biofilm. J Bacteriol 2005; 187:7193-203. [PMID: 16237003 PMCID: PMC1272965 DOI: 10.1128/jb.187.21.7193-7203.2005] [Citation(s) in RCA: 326] [Impact Index Per Article: 17.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The human mucosal surface is colonized by the indigenous microflora, which normally maintains an ecological balance among different species. Certain environmental or biological factors, however, may trigger disruption of this balance, leading to microbial diseases. In this study, we used two oral bacterial species, Streptococcus mutans and Streptococcus sanguinis (formerly S. sanguis), as a model to probe the possible mechanisms of competition/coexistence between different species which occupy the same ecological niche. We show that the two species engage in a multitude of antagonistic interactions temporally and spatially; occupation of a niche by one species precludes colonization by the other, while simultaneous colonization by both species results in coexistence. Environmental conditions, such as cell density, nutritional availability, and pH, play important roles in determining the outcome of these interactions. Genetic and biochemical analyses reveal that these interspecies interactions are possibly mediated through a well-regulated production of chemicals, such as bacteriocins (produced by S. mutans) and hydrogen peroxide (produced by S. sanguinis). Consistent with the phenotypic characteristics, production of bacteriocins and H2O2 are regulated by environmental conditions, as well as by juxtaposition of the two species. These sophisticated interspecies interactions could play an essential part in balancing competition/coexistence within multispecies microbial communities.
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Affiliation(s)
- Jens Kreth
- Department of Oral Biology and Medicine, UCLA School of Dentistry, P.O. Box 951668, Los Angeles, CA 90095-1668, USA
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