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Lewin GR, Evans ER, Whiteley M. Microbial interactions impact stress tolerance in a model oral community. Microbiol Spectr 2024:e0100524. [PMID: 39269155 DOI: 10.1128/spectrum.01005-24] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2024] [Accepted: 08/20/2024] [Indexed: 09/15/2024] Open
Abstract
Understanding the molecular mechanisms governing microbial interactions is crucial for unraveling the complexities of microbial communities and their ecological impacts. Here, we employed a two-species model system comprising the oral bacteria Aggregatibacter actinomycetemcomitans and Streptococcus gordonii to investigate how synergistic and antagonistic interactions between microbes impact their resilience to environmental change and invasion by other microbes. We used an in vitro colony biofilm model and focused on two S. gordonii-produced extracellular molecules, L-lactate and H2O2, which are known to impact fitness of this dual-species community. While the ability of A. actinomycetemcomitans to cross-feed on S. gordonii-produced L-lactate enhanced its fitness during co-culture, this function showed little impact on the ability of co-cultures to resist environmental change. In fact, the ability of A. actinomycetemcomitans to catabolize L-lactate may be detrimental in the presence of tetracycline, highlighting the complexity of interactions under antimicrobial stress. Furthermore, H2O2, known for its antimicrobial properties, had negative impacts on both species in our model system. However, H2O2 production by S. gordonii enhanced A. actinomycetemcomitans tolerance to tetracycline, suggesting a protective role under antibiotic pressure. Finally, S. gordonii significantly inhibited the bacterium Serratia marcescens from invading in vitro biofilms, but this inhibition was lost during co-culture with A. actinomycetemcomitans and in a murine abscess model, where S. gordonii actually promoted S. marcescens invasion. These data indicate that microbial interactions can impact fitness of a bacterial community upon exposure to stresses, but these impacts are highly environment dependent. IMPORTANCE Microbial interactions are critical modulators of the emergence of microbial communities and their functions. However, how these interactions impact the fitness of microbes in established communities upon exposure to environmental stresses is poorly understood. Here, we utilized a two-species community consisting of Aggregatibacter actinomycetemcomitans and Streptococcus gordonii to examine the impact of synergistic and antagonistic interactions on microbial resilience to environmental fluctuations and susceptibility to microbial invasion. We focused on the S. gordonii-produced extracellular molecules, L-lactate and H2O2, which have been shown to mediate interactions between these two microbes. We discovered that seemingly beneficial functions, such as A. actinomycetemcomitans cross-feeding on S. gordonii-produced L-Lactate, can paradoxically exacerbate vulnerabilities, such as susceptibility to antibiotics. Moreover, our data highlight the context-dependent nature of microbial interactions, emphasizing that a seemingly potent antimicrobial, such as H2O2, can have both synergistic and antagonistic effects on a microbial community dependent on the environment.
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Affiliation(s)
- Gina R Lewin
- School of Biological Sciences and Center for Microbial Dynamics and Infection, Georgia Institute of Technology, Atlanta, Georgia, USA
- Emory-Children's Cystic Fibrosis Center, Atlanta, Georgia, USA
| | - Emma R Evans
- School of Biological Sciences and Center for Microbial Dynamics and Infection, Georgia Institute of Technology, Atlanta, Georgia, USA
- Emory-Children's Cystic Fibrosis Center, Atlanta, Georgia, USA
| | - Marvin Whiteley
- School of Biological Sciences and Center for Microbial Dynamics and Infection, Georgia Institute of Technology, Atlanta, Georgia, USA
- Emory-Children's Cystic Fibrosis Center, Atlanta, Georgia, USA
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Ye D, Liu Y, Li J, Zhou J, Cao J, Wu Y, Wang X, Fang Y, Ye X, Zou J, Ma Q. Competitive dynamics and balance between Streptococcus mutans and commensal streptococci in oral microecology. Crit Rev Microbiol 2024:1-12. [PMID: 39132685 DOI: 10.1080/1040841x.2024.2389386] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2024] [Revised: 06/01/2024] [Accepted: 08/02/2024] [Indexed: 08/13/2024]
Abstract
Dental caries, as a biofilm-related disease, is closely linked to dysbiosis in microbial ecology within dental biofilms. Beyond its impact on oral health, bacteria within the oral cavity pose systemic health risks by potentially entering the bloodstream, thereby increasing susceptibility to bacterial endocarditis, among other related diseases. Streptococcus mutans, a principal cariogenic bacterium, possesses virulence factors crucial to the pathogenesis of dental caries. Its ability to adhere to tooth surfaces, produce glucans for biofilm formation, and metabolize sugars into lactic acid contributes to enamel demineralization and the initiation of carious lesions. Its aciduricity and ability to produce bacteriocins enable a competitive advantage, allowing it to thrive in acidic environments and dominate in changing oral microenvironments. In contrast, commensal streptococci, such as Streptococcus sanguinis, Streptococcus gordonii, and Streptococcus salivarius, act as primary colonizers and compete with S. mutans for adherence sites and nutrients during biofilm formation. This competition involves the production of alkali, peroxides, and antibacterial substances, thereby inhibiting S. mutans growth and maintaining microbial balance. This dynamic interaction influences the balance of oral microbiota, with disruptions leading to shifts in microbial composition that are marked by rapid increases in S. mutans abundance, contributing to the onset of dental caries. Thus, understanding the dynamic interactions between commensal and pathogenic bacteria in oral microecology is important for developing effective strategies to promote oral health and prevent dental caries. This review highlights the roles and competitive interactions of commensal bacteria and S. mutans in oral microecology, emphasizing the importance of maintaining oral microbial balance for health, and discusses the pathological implications of perturbations in this balance.
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Affiliation(s)
- Dingwei Ye
- State Key Laboratory of Oral Diseases and National Center for Stomatology and National Clinical Research Center for Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu, Sichuan, China
- Department of Pediatric Dentistry, West China Hospital of Stomatology, Sichuan University, Chengdu, China
| | - Yaqi Liu
- State Key Laboratory of Oral Diseases and National Center for Stomatology and National Clinical Research Center for Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu, Sichuan, China
- Department of Pediatric Dentistry, West China Hospital of Stomatology, Sichuan University, Chengdu, China
| | - Jing Li
- State Key Laboratory of Oral Diseases and National Center for Stomatology and National Clinical Research Center for Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu, Sichuan, China
- Department of Pediatric Dentistry, West China Hospital of Stomatology, Sichuan University, Chengdu, China
| | - Jing Zhou
- State Key Laboratory of Oral Diseases and National Center for Stomatology and National Clinical Research Center for Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu, Sichuan, China
- Department of Pediatric Dentistry, West China Hospital of Stomatology, Sichuan University, Chengdu, China
| | - Jingwei Cao
- State Key Laboratory of Oral Diseases and National Center for Stomatology and National Clinical Research Center for Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu, Sichuan, China
- Department of Pediatric Dentistry, West China Hospital of Stomatology, Sichuan University, Chengdu, China
| | - Yumeng Wu
- State Key Laboratory of Oral Diseases and National Center for Stomatology and National Clinical Research Center for Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu, Sichuan, China
- Department of Pediatric Dentistry, West China Hospital of Stomatology, Sichuan University, Chengdu, China
| | - Xinyue Wang
- State Key Laboratory of Oral Diseases and National Center for Stomatology and National Clinical Research Center for Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu, Sichuan, China
- Department of Pediatric Dentistry, West China Hospital of Stomatology, Sichuan University, Chengdu, China
| | - Yuwen Fang
- State Key Laboratory of Oral Diseases and National Center for Stomatology and National Clinical Research Center for Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu, Sichuan, China
- Department of Pediatric Dentistry, West China Hospital of Stomatology, Sichuan University, Chengdu, China
| | - Xingchen Ye
- State Key Laboratory of Oral Diseases and National Center for Stomatology and National Clinical Research Center for Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu, Sichuan, China
- Department of Pediatric Dentistry, West China Hospital of Stomatology, Sichuan University, Chengdu, China
| | - Jing Zou
- State Key Laboratory of Oral Diseases and National Center for Stomatology and National Clinical Research Center for Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu, Sichuan, China
- Department of Pediatric Dentistry, West China Hospital of Stomatology, Sichuan University, Chengdu, China
| | - Qizhao Ma
- State Key Laboratory of Oral Diseases and National Center for Stomatology and National Clinical Research Center for Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu, Sichuan, China
- Department of Pediatric Dentistry, West China Hospital of Stomatology, Sichuan University, Chengdu, China
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3
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Williams I, Tuckerman JS, Peters DI, Bangs M, Williams E, Shin IJ, Kaspar JR. A Strain of Streptococcus mitis Inhibits Biofilm Formation of Caries Pathogens via Abundant Hydrogen Peroxide Production. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.08.06.606862. [PMID: 39149263 PMCID: PMC11326308 DOI: 10.1101/2024.08.06.606862] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Indexed: 08/17/2024]
Abstract
Commensal oral streptococci that colonize supragingival biofilms deploy mechanisms to combat competitors within their niche. Here, we determined that Streptococcus mitis more effectively inhibited biofilm formation of Streptococcus mutans within a seven species panel. This phenotype was common amongst all assayed isolates of S. mutans, but was specific to a single strain of S. mitis, ATCC 49456. The growth inhibitory factor was not effectively carried in spent supernatants of S. mitis. However, we documented ATCC 49456 to accumulate 4-5 times more hydrogen peroxide (H2O2) than other species tested, and 5-18 times more than other S. mitis strains assayed. The S. mutans biofilm formation inhibitory phenotype was reduced when grown in media containing catalase or with a S. mitis mutant of pyruvate oxidase (spxB; pox), confirming that SpxB-dependent H2O2 production was the main antagonistic factor. Addition of S. mitis within hours after S. mutans inoculation was effective at reducing biofilm biomass, but not for 24 h pre-formed biofilms. Transcriptome analysis revealed responses for both S. mitis and S. mutans, with several S. mutans differentially expressed genes following a gene expression pattern previously described, while others being unique to the interaction with S. mitis. Finally, we show that S. mitis also affected coculture biofilm formation of several other commensal streptococci. Our study shows that strains with abundant H2O2 production are effective at inhibiting initial growth of caries pathogens like S. mutans, but are less effective at disrupting pre-formed biofilms and have the potential to influence the stability of other oral commensal strains.
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Affiliation(s)
| | | | - Daniel I. Peters
- Division of Biosciences, The Ohio State University College of Dentistry, Columbus, Ohio
| | - Madisen Bangs
- Division of Biosciences, The Ohio State University College of Dentistry, Columbus, Ohio
| | - Emily Williams
- Division of Biosciences, The Ohio State University College of Dentistry, Columbus, Ohio
| | - Iris J. Shin
- Division of Biosciences, The Ohio State University College of Dentistry, Columbus, Ohio
| | - Justin R. Kaspar
- Division of Biosciences, The Ohio State University College of Dentistry, Columbus, Ohio
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Treerat P, de Mattos C, Burnside M, Zhang H, Zhu Y, Zou Z, Anderson D, Wu H, Merritt J, Kreth J. Ribosomal-processing cysteine protease homolog modulates Streptococcus mutans glucan production and interkingdom interactions. J Bacteriol 2024; 206:e0010424. [PMID: 38899897 PMCID: PMC11270869 DOI: 10.1128/jb.00104-24] [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: 03/25/2024] [Accepted: 06/02/2024] [Indexed: 06/21/2024] Open
Abstract
Glucan-dependent biofilm formation is a crucial process in the establishment of Streptococcus mutans as a cariogenic oral microbe. The process of glucan formation has been investigated in great detail, with glycosyltransferases GtfB, GtfC, and GtfD shown to be indispensable for the synthesis of glucans from sucrose. Glucan production can be visualized during biofilm formation through fluorescent labeling, and its abundance, as well as the effect of glucans on general biofilm architecture, is a common phenotype to study S. mutans virulence regulation. Here, we describe an entirely new phenotype associated with glucan production, caused by a mutation in the open reading frame SMU_848, which is located in an operon encoding ribosome-associated proteins. This mutation led to the excess production and accumulation of glucan-containing droplets on the surface of biofilms formed on agar plates after prolonged incubation. While not characterized in S. mutans, SMU_848 shows homology to the phage-related ribosomal protease Prp, essential in cleaving off the N-terminal extension of ribosomal protein L27 for functional ribosome assembly in Staphylococcus aureus. We present a further characterization of SMU_848/Prp, demonstrating that the deletion of this gene leads to significant changes in S. mutans gtfBC expression. Surprisingly, it also profoundly impacts the interkingdom interaction between S. mutans and Candida albicans, a relevant dual-species interaction implicated in severe early childhood caries. The presented data support a potential broader role for SMU_848/Prp, possibly extending its functionality beyond the ribosomal network to influence important ecological processes. IMPORTANCE Streptococcus mutans is an important member of the oral biofilm and is implicated in the initiation of caries. One of the main virulence mechanisms is the glucan-dependent formation of biofilms. We identified a new player in the regulation of glucan production, SMU_848, which is part of an operon that also encodes for ribosomal proteins L27 and L21. A mutation in SMU_848, which encodes a phage-related ribosomal protease Prp, leads to a significant accumulation of glucan-containing droplets on S. mutans biofilms, a previously unknown phenotype. Further investigations expanded our knowledge about the role of SMU_848 beyond its role in glucan production, including significant involvement in interkingdom interactions, thus potentially playing a global role in the virulence regulation of S. mutans.
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Affiliation(s)
- Puthayalai Treerat
- Biomaterial and Biomedical Sciences, School of Dentistry, Oregon Health & Science University (OHSU), Portland, Oregon, USA
- Division of Infectious Diseases and International Health, Department of Medicine, University of Virginia, Charlottesville, Virginia, USA
| | - Camilla de Mattos
- Biomaterial and Biomedical Sciences, School of Dentistry, Oregon Health & Science University (OHSU), Portland, Oregon, USA
| | - Molly Burnside
- Biomaterial and Biomedical Sciences, School of Dentistry, Oregon Health & Science University (OHSU), Portland, Oregon, USA
| | - Hua Zhang
- Biomaterial and Biomedical Sciences, School of Dentistry, Oregon Health & Science University (OHSU), Portland, Oregon, USA
| | - Yanting Zhu
- Biomaterial and Biomedical Sciences, School of Dentistry, Oregon Health & Science University (OHSU), Portland, Oregon, USA
| | - Zhengzhong Zou
- Biomaterial and Biomedical Sciences, School of Dentistry, Oregon Health & Science University (OHSU), Portland, Oregon, USA
| | - David Anderson
- Biomaterial and Biomedical Sciences, School of Dentistry, Oregon Health & Science University (OHSU), Portland, Oregon, USA
| | - Hui Wu
- Biomaterial and Biomedical Sciences, School of Dentistry, Oregon Health & Science University (OHSU), Portland, Oregon, USA
| | - Justin Merritt
- Biomaterial and Biomedical Sciences, School of Dentistry, Oregon Health & Science University (OHSU), Portland, Oregon, USA
- Department of Molecular Microbiology and Immunology, School of Medicine, Oregon Health & Science University (OHSU), Portland, Oregon, USA
| | - Jens Kreth
- Biomaterial and Biomedical Sciences, School of Dentistry, Oregon Health & Science University (OHSU), Portland, Oregon, USA
- Department of Molecular Microbiology and Immunology, School of Medicine, Oregon Health & Science University (OHSU), Portland, Oregon, USA
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5
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Baty JJ, Stoner SN, McDaniel MS, Huffines JT, Edmonds SE, Evans NJ, Novak L, Scoffield JA. An oral commensal attenuates Pseudomonas aeruginosa-induced airway inflammation and modulates nitrite flux in respiratory epithelium. Microbiol Spectr 2023; 11:e0219823. [PMID: 37800950 PMCID: PMC10715204 DOI: 10.1128/spectrum.02198-23] [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: 05/24/2023] [Accepted: 08/14/2023] [Indexed: 10/07/2023] Open
Abstract
IMPORTANCE Respiratory infections are a leading cause of morbidity and mortality in people with cystic fibrosis (CF). These infections are polymicrobial in nature with overt pathogens and other colonizing microbes present. Microbiome data have indicated that the presence of oral commensal bacteria in the lungs is correlated with improved outcomes. We hypothesize that one oral commensal, Streptococcus parasanguinis, inhibits CF pathogens and modulates the host immune response. One major CF pathogen is Pseudomonas aeruginosa, a Gram-negative, opportunistic bacterium with intrinsic drug resistance and an arsenal of virulence factors. We have previously shown that S. parasanguinis inhibits P. aeruginosa in vitro in a nitrite-dependent manner through the production of reactive nitrogen intermediates. In this study, we demonstrate that while this mechanism is evident in a cell culture model of the CF airway, an alternative mechanism by which S. parasanguinis may improve outcomes for people with CF is through immunomodulation.
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Affiliation(s)
- Joshua J. Baty
- Department of Microbiology, University of Alabama at Birmingham, Birmingham, Alabama, USA
| | - Sara N. Stoner
- Department of Microbiology, University of Alabama at Birmingham, Birmingham, Alabama, USA
| | - Melissa S. McDaniel
- Department of Microbiology, University of Alabama at Birmingham, Birmingham, Alabama, USA
| | - Joshua T. Huffines
- Department of Microbiology, University of Alabama at Birmingham, Birmingham, Alabama, USA
| | - Sara E. Edmonds
- Department of Microbiology, University of Alabama at Birmingham, Birmingham, Alabama, USA
| | - Nicholas J. Evans
- Department of Microbiology, University of Alabama at Birmingham, Birmingham, Alabama, USA
| | - Lea Novak
- Department of Microbiology, University of Alabama at Birmingham, Birmingham, Alabama, USA
| | - Jessica A. Scoffield
- Department of Microbiology, University of Alabama at Birmingham, Birmingham, Alabama, USA
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Labossiere A, Ramsey M, Merritt J, Kreth J. Molecular commensalism-how to investigate underappreciated health-associated polymicrobial communities. mBio 2023; 14:e0134223. [PMID: 37754569 PMCID: PMC10653818 DOI: 10.1128/mbio.01342-23] [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] [Indexed: 09/28/2023] Open
Abstract
The study of human commensal bacteria began with the first observation of prokaryotes >340 years ago. Since then, the study of human-associated microbes has been justifiably biased toward the study of infectious pathogens. However, the role of commensal microbes has in recent years begun to be understood with some appreciation of them as potential protectors of host health rather than bystanders. As our understanding of these valuable microbes grows, it highlights how much more remains to be learned about them and their roles in maintaining health. We note here that a thorough framework for the study of commensals, both in vivo and in vitro is overall lacking compared to well-developed methodologies for pathogens. The modification and application of methods for the study of pathogens can work well for the study of commensals but is not alone sufficient to properly characterize their relationships. This is because commensals live in homeostasis with the host and within complex communities. One difficulty is determining which commensals have a quantifiable impact on community structure and stability as well as host health, vs benign microbes that may indeed serve only as bystanders. Human microbiomes are composed of bacteria, archaea, fungi, and viruses. This review focuses particularly on oral bacteria, yet many of the principles of commensal impacts on host health observed in the mouth can translate well to other host sites. Here, we discuss the value of commensals, the shortcomings involved in model systems for their study, and some of the more notable impacts they have upon not only each other but host health.
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Affiliation(s)
- Alex Labossiere
- Department of Cell and Molecular Biology, The University of Rhode Island, Kingston, Rhode Island, USA
| | - Matthew Ramsey
- Department of Cell and Molecular Biology, The University of Rhode Island, Kingston, Rhode Island, USA
| | - Justin Merritt
- Biomaterial and Biomedical Sciences, Oregon Health and Science University, School of Dentistry, Portland, Oregon, USA
- Department of Molecular Microbiology and Immunology, School of Medicine, Oregon Health and Science University, Portland, Oregon, USA
| | - Jens Kreth
- Biomaterial and Biomedical Sciences, Oregon Health and Science University, School of Dentistry, Portland, Oregon, USA
- Department of Molecular Microbiology and Immunology, School of Medicine, Oregon Health and Science University, Portland, Oregon, USA
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Jiang W, Xie Z, Huang S, Huang Q, Chen L, Gao X, Lin Z. Targeting cariogenic pathogens and promoting competitiveness of commensal bacteria with a novel pH-responsive antimicrobial peptide. J Oral Microbiol 2022; 15:2159375. [PMID: 36570976 PMCID: PMC9788686 DOI: 10.1080/20002297.2022.2159375] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Novel ecological antimicrobial approaches to dental caries focus on inhibiting cariogenic pathogens while enhancing the growth of health-associated commensal communities or suppressing cariogenic virulence without affecting the diversity of oral microbiota, which emphasize the crucial role of establishing a healthy microbiome in caries prevention. Considering that the acidified cariogenic microenvironment leads to the dysbiosis of microecology and demineralization of enamel, exploiting the acidic pH as a bioresponsive trigger to help materials and medications target cariogenic pathogens is a promising strategy to develop novel anticaries approaches. In this study, a pH-responsive antimicrobial peptide, LH12, was designed utilizing the pH-sensitivity of histidine, which showed higher cationicity and stronger interactions with bacterial cytomembranes at acidic pH. Streptococcus mutans was used as the in vitro caries model to evaluate the inhibitory effects of LH12 on the cariogenic properties, such as biofilm formation, biofilm morphology, acidurance, acidogenicity, and exopolysaccharides synthesis. The dual-species model of Streptococcus mutans and Streptococcus gordonii was established in vitro to evaluate the regulation effects of LH12 on the mixed species microbial community containing both cariogenic bacteria and commensal bacteria. LH12 suppressed the cariogenic properties and regulated the bacterial composition to a healthier condition through a dual-functional mechanism. Firstly, LH12-targeted cariogenic pathogens in response to the acidified microenvironment and suppressed the cariogenic virulence by inhibiting the expression of multiple virulence genes and two-component signal transduction systems. Additionally, LH12 elevated H2O2 production of the commensal bacteria and subsequently improved the ecological competitiveness of the commensals. The dual-functional mechanism made LH12 a potential bioresponsive approach to caries management.
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Affiliation(s)
- Wentao Jiang
- Hospital of Stomatology, Guangdong Provincial Key Laboratory of Stomatology, Guanghua School of Stomatology, Sun Yat-sen University, Guangzhou, GuangdongChina
| | - Zhuo Xie
- Hospital of Stomatology, Guangdong Provincial Key Laboratory of Stomatology, Guanghua School of Stomatology, Sun Yat-sen University, Guangzhou, GuangdongChina
| | - Shuheng Huang
- Hospital of Stomatology, Guangdong Provincial Key Laboratory of Stomatology, Guanghua School of Stomatology, Sun Yat-sen University, Guangzhou, GuangdongChina
| | - Qiting Huang
- Hospital of Stomatology, Guangdong Provincial Key Laboratory of Stomatology, Guanghua School of Stomatology, Sun Yat-sen University, Guangzhou, GuangdongChina
| | - Lingling Chen
- Hospital of Stomatology, Guangdong Provincial Key Laboratory of Stomatology, Guanghua School of Stomatology, Sun Yat-sen University, Guangzhou, GuangdongChina
| | - Xianling Gao
- Hospital of Stomatology, Guangdong Provincial Key Laboratory of Stomatology, Guanghua School of Stomatology, Sun Yat-sen University, Guangzhou, GuangdongChina
| | - Zhengmei Lin
- Hospital of Stomatology, Guangdong Provincial Key Laboratory of Stomatology, Guanghua School of Stomatology, Sun Yat-sen University, Guangzhou, GuangdongChina,CONTACT Zhengmei Lin Hospital of Stomatology, Guangdong Provincial Key Laboratory of Stomatology, Guanghua School of Stomatology, Sun Yat-sen University, Guangzhou, Guangdong510055, China
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Cui G, Li P, Wu R, Lin H. Streptococcus mutans membrane vesicles inhibit the biofilm formation of Streptococcus gordonii and Streptococcus sanguinis. AMB Express 2022; 12:154. [PMID: 36508003 PMCID: PMC9743899 DOI: 10.1186/s13568-022-01499-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2022] [Accepted: 12/02/2022] [Indexed: 12/14/2022] Open
Abstract
Streptococcus mutans, whose main virulence factor is glucosyltransferase (Gtf), has a substantial impact on the development of dental caries. S. mutans membrane vesicles (MVs), which are rich in Gtfs, have been shown to affect biofilm formation of other microorganisms. Streptococcus gordonii and Streptococcus sanguinis are initial colonizers of tooth surfaces, which provide attachment sites for subsequent microorganisms and are crucial in the development of oral biofilms. S. mutans and S. gordonii, as well as S. mutans and S. sanguinis, have a complex competitive and cooperative relationship, but it is unclear whether S. mutans MVs play a role in these interspecific interactions. Therefore, we co-cultured S. mutans MVs, having or lacking Gtfs, with S. gordonii and S. sanguinis. Our results showed that S. mutans MVs inhibited biofilm formation of S. gordonii and S. sanguinis but did not affect their planktonic growth; contrastingly, S. mutans ΔgtfBC mutant MVs had little effect on both their growth and biofilm formation. Additionally, there were fewer and more dispersed bacteria in the biofilms of the S. mutans MV-treated group than that in the control group. Furthermore, the expression levels of the biofilm-related virulence factors GtfG, GtfP, and SpxB in S. gordonii and S. sanguinis were significantly downregulated in response to S. mutans MVs. In conclusion, the results of our study showed that S. mutans MVs inhibited biofilm formation of S. gordonii and S. sanguinis, revealing an important role for MVs in interspecific interactions.
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Affiliation(s)
- Guxin Cui
- grid.12981.330000 0001 2360 039XHospital of Stomatology, Guanghua School of Stomatology, Sun Yat-sen University, Guangzhou, China ,grid.12981.330000 0001 2360 039XGuangdong Provincial Key Laboratory of Stomatology, Sun Yat-sen University, Guangzhou, China
| | - Pengpeng Li
- grid.12981.330000 0001 2360 039XHospital of Stomatology, Guanghua School of Stomatology, Sun Yat-sen University, Guangzhou, China ,grid.12981.330000 0001 2360 039XGuangdong Provincial Key Laboratory of Stomatology, Sun Yat-sen University, Guangzhou, China
| | - Ruixue Wu
- grid.12981.330000 0001 2360 039XHospital of Stomatology, Guanghua School of Stomatology, Sun Yat-sen University, Guangzhou, China ,grid.12981.330000 0001 2360 039XGuangdong Provincial Key Laboratory of Stomatology, Sun Yat-sen University, Guangzhou, China
| | - Huancai Lin
- grid.12981.330000 0001 2360 039XHospital of Stomatology, Guanghua School of Stomatology, Sun Yat-sen University, Guangzhou, China ,grid.12981.330000 0001 2360 039XGuangdong Provincial Key Laboratory of Stomatology, Sun Yat-sen University, Guangzhou, China
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9
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Abstract
Oral commensal streptococci are primary colonizers of the oral cavity. These streptococci produce many adhesins, metabolites, and antimicrobials that modulate microbial succession and diversity within the oral cavity. Often, oral commensal streptococci antagonize cariogenic and periodontal pathogens such as Streptococcus mutans and Porphyromonas gingivalis, respectively. Mechanisms of antagonism are varied and range from the generation of hydrogen peroxide, competitive metabolite scavenging, the generation of reactive nitrogen intermediates, and bacteriocin production. Furthermore, several oral commensal streptococci have been shown to alter the host immune response at steady state and in response to oral pathogens. Collectively, these features highlight the remarkable ability of oral commensal streptococci to regulate the structure and function of the oral microbiome. In this review, we discuss mechanisms used by oral commensal streptococci to interact with diverse oral pathogens, both physically and through the production of antimicrobials. Finally, we conclude by exploring the critical roles of oral commensal streptococci in modulating the host immune response and maintaining health and homeostasis.
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Affiliation(s)
- Joshua J. Baty
- Department of Microbiology, School of Medicine, University of Alabama at Birmingham, Birmingham, Alabama, USA
| | - Sara N. Stoner
- Department of Microbiology, School of Medicine, University of Alabama at Birmingham, Birmingham, Alabama, USA
| | - Jessica A. Scoffield
- Department of Microbiology, School of Medicine, University of Alabama at Birmingham, Birmingham, Alabama, USA
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10
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Quantification of Extracellular DNA Network Abundance and Architecture within Streptococcus gordonii Biofilms Reveals Modulatory Factors. Appl Environ Microbiol 2022; 88:e0069822. [PMID: 35695569 PMCID: PMC9275248 DOI: 10.1128/aem.00698-22] [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: 12/15/2022] Open
Abstract
Extracellular DNA (eDNA) is an important component of biofilm matrix that serves to maintain biofilm structural integrity, promotes genetic exchange within the biofilm, and provides protection against antimicrobial compounds. Advances in microscopy techniques have provided evidence of the cobweb- or lattice-like structures of eDNA within biofilms from a range of environmental niches. However, methods to reliably assess the abundance and architecture of eDNA remain lacking. This study aimed to address this gap by development of a novel, high-throughput image acquisition and analysis platform for assessment of eDNA networks in situ within biofilms. Utilizing Streptococcus gordonii as the model, the capacity for this imaging system to reliably detect eDNA networks and monitor changes in abundance and architecture (e.g., strand length and branch number) was verified. Evidence was provided of a synergy between glucans and eDNA matrices, while it was revealed that surface-bound nuclease SsnA could modify these eDNA structures under conditions permissive for enzymatic activity. Moreover, cross talk between the competence and hexaheptapeptide permease systems was shown to regulate eDNA release by S. gordonii. This novel imaging system can be applied across the wider field of biofilm research, with potential to significantly advance interrogation of the mechanisms by which the eDNA network architecture develops, how it can influence biofilm properties, and how it may be targeted for therapeutic benefit. IMPORTANCE Extracellular DNA (eDNA) is critical for maintaining the structural integrity of many microbial biofilms, making it an attractive target for the management of biofilms. However, our knowledge and targeting of eDNA are currently hindered by a lack of tools for the quantitative assessment of eDNA networks within biofilms. Here, we demonstrate use of a novel image acquisition and analysis platform with the capacity to reliably monitor the abundance and architecture of eDNA networks. Application of this tool to Streptococcus gordonii biofilms has provided new insights into how eDNA networks are stabilized within the biofilm and the pathways that can regulate eDNA release. This highlights how exploitation of this novel imaging system across the wider field of biofilm research has potential to significantly advance interrogation of the mechanisms by which the eDNA network architecture develops, how it can influence biofilm properties, and how it may be targeted for therapeutic benefit.
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Development of a Versatile, Low-Cost Electrochemical System to Study Biofilm Redox Activity at the Micron Scale. Appl Environ Microbiol 2022; 88:e0043422. [PMID: 35758758 PMCID: PMC9328185 DOI: 10.1128/aem.00434-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Spatially resolving chemical landscapes surrounding microbial communities can provide insight into chemical interactions that dictate cellular physiology. Electrochemical techniques provide an attractive option for studying these interactions due to their robustness and high sensitivity. Unfortunately, commercial electrochemical platforms that are capable of measuring chemical activity on the micron scale are often expensive and do not easily perform multiple scanning techniques. Here, we report development of an inexpensive electrochemical system that features a combined micromanipulator and potentiostat component capable of scanning surfaces while measuring molecular concentrations or redox profiles. We validate this experimental platform for biological use with a two-species biofilm model composed of the oral bacterial pathogen Aggregatibacter actinomycetemcomitans and the oral commensal Streptococcus gordonii. We measure consumption of H2O2 by A. actinomycetemcomitans biofilms temporally and spatially, providing new insights into how A. actinomycetemcomitans responds to this S. gordonii-produced metabolite. We advance our platform to spatially measure redox activity above biofilms. Our analysis supports that redox activity surrounding biofilms is species specific, and the region immediately above an S. gordonii biofilm is highly oxidized compared to that above an A. actinomycetemcomitans biofilm. This work provides description and validation of a versatile, quantitative framework for studying bacterial redox-mediated physiology in an integrated and easily adaptable experimental platform. IMPORTANCE Scanning electrochemical probe microscopy methods can provide information of the chemical environment along a spatial surface with micron-scale resolution. These methods often require expensive instruments that perform optimized and highly sensitive niche techniques. Here, we describe a novel system that combines a micromanipulator that scans micron-sized electrodes across the surface of bacterial biofilms and a potentiostat, which performs various electrochemical techniques. This platform allows for spatial measurement of chemical gradients above live bacteria in real time, and as proof of concept, we utilize this setup to map H2O2 detoxification above an oral pathogen biofilm. We increased the versatility of this platform further by mapping redox potentials of biofilms in real time on the micron scale. Together, this system provides a technical framework for studying chemical interactions among microbes.
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Kikuchi Y, Okamoto-Shibayama K, Kokubu E, Ishihara K. OxyR inactivation reduces the growth rate and oxidative stress defense in Capnocytophaga ochracea. Anaerobe 2021; 72:102466. [PMID: 34673216 DOI: 10.1016/j.anaerobe.2021.102466] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2021] [Revised: 09/22/2021] [Accepted: 10/17/2021] [Indexed: 11/20/2022]
Abstract
OBJECTIVE The human oral cavity harbors several bacteria. Among them, Capnocytophaga ochracea, a facultative anaerobe, is responsible for the early phase of dental plaque formation. In this phase, the tooth surface or tissue is exposed to various oxidative stresses. For colonization in the dental plaque phase, a response by hydrogen peroxide (H2O2)-sensing transcriptional regulators, such as OxyR, may be necessary. However, to date, no study has elucidated the role of OxyR protein in C. ochracea. METHODS Insertional mutagenesis was used to create an oxyR mutant, and gene expression was evaluated by reverse transcription-polymerase chain reaction and quantitative real-time reverse transcription-polymerase chain reaction. Bacterial growth curves were generated by turbidity measurement, and the sensitivity of the oxyR mutant to H2O2 was assessed using the disc diffusion assay. Finally, a two-compartment system was used to assess biofilm formation. RESULTS The oxyR mutant grew slower than the wild-type under anaerobic conditions. The agar diffusion assay revealed that the oxyR mutant had increased sensitivity to H2O2. The transcript levels of oxidative stress defense genes, sod, ahpC, and trx, were lower in the oxyR mutant than in the wild-type strain. The turbidity of C. ochracea, simultaneously co-cultured with Streptococcus gordonii, was lower than that observed under conditions of homotypic growth. Moreover, the percentage decrease in growth of the oxyR mutant was significantly higher than that of the wild-type. CONCLUSIONS These results show that OxyR in C. ochracea regulates adequate in vitro growth and escapes oxidative stress.
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Affiliation(s)
- Yuichiro Kikuchi
- Oral Health Science Center, Tokyo Dental College, 2-1-14 Kanda-Misakicho, Chiyoda-ku, Tokyo, 101-0061, Japan; Department of Microbiology, Tokyo Dental College, 2-1-14 Kanda-Misakicho, Chiyoda-ku, Tokyo, 101-0061, Japan.
| | - Kazuko Okamoto-Shibayama
- Oral Health Science Center, Tokyo Dental College, 2-1-14 Kanda-Misakicho, Chiyoda-ku, Tokyo, 101-0061, Japan; Department of Microbiology, Tokyo Dental College, 2-1-14 Kanda-Misakicho, Chiyoda-ku, Tokyo, 101-0061, Japan.
| | - Eitoyo Kokubu
- Oral Health Science Center, Tokyo Dental College, 2-1-14 Kanda-Misakicho, Chiyoda-ku, Tokyo, 101-0061, Japan; Department of Microbiology, Tokyo Dental College, 2-1-14 Kanda-Misakicho, Chiyoda-ku, Tokyo, 101-0061, Japan.
| | - Kazuyuki Ishihara
- Oral Health Science Center, Tokyo Dental College, 2-1-14 Kanda-Misakicho, Chiyoda-ku, Tokyo, 101-0061, Japan; Department of Microbiology, Tokyo Dental College, 2-1-14 Kanda-Misakicho, Chiyoda-ku, Tokyo, 101-0061, Japan.
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Amino Sugars Reshape Interactions between Streptococcus mutans and Streptococcus gordonii. Appl Environ Microbiol 2020; 87:AEM.01459-20. [PMID: 33097515 DOI: 10.1128/aem.01459-20] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2020] [Accepted: 10/13/2020] [Indexed: 12/19/2022] Open
Abstract
Amino sugars, particularly glucosamine (GlcN) and N-acetylglucosamine (GlcNAc), are abundant carbon and nitrogen sources supplied in host secretions and in the diet to the biofilms colonizing the human oral cavity. Evidence is emerging that these amino sugars provide ecological advantages to beneficial commensals over oral pathogens and pathobionts. Here, we performed transcriptome analysis on Streptococcus mutans and Streptococcus gordonii growing in single-species or dual-species cultures with glucose, GlcN, or GlcNAc as the primary carbohydrate source. Compared to glucose, GlcN caused drastic transcriptomic shifts in each species of bacteria when it was cultured alone. Likewise, cocultivation in the presence of GlcN yielded transcriptomic profiles that were dramatically different from the single-species results from GlcN-grown cells. In contrast, GlcNAc elicited only minor changes in the transcriptome of either organism in single- and dual-species cultures. Interestingly, genes involved in pyruvate metabolism were among the most significantly affected by GlcN in both species, and these changes were consistent with measurements of pyruvate in culture supernatants. Differing from what was found in a previous report, growth of S. mutans alone with GlcN inhibited the expression of multiple operons required for mutacin production. Cocultivation with S. gordonii consistently increased the expression of two manganese transporter operons (slo and mntH) and decreased expression of mutacin genes in S. mutans Conversely, S. gordonii appeared to be less affected by the presence of S. mutans but did show increases in genes for biosynthetic processes in the cocultures. In conclusion, amino sugars profoundly alter the interactions between pathogenic and commensal streptococci by reprogramming central metabolism.IMPORTANCE Carbohydrate metabolism is central to the development of dental caries. A variety of sugars available to dental microorganisms influence the development of caries by affecting the physiology, ecology, and pathogenic potential of tooth biofilms. Using two well-characterized oral bacteria, one pathogen (Streptococcus mutans) and one commensal (Streptococcus gordonii), in an RNA deep-sequencing analysis, we studied the impact of two abundant amino sugars on bacterial gene expression and interspecies interactions. The results indicated large-scale remodeling of gene expression induced by GlcN in particular, affecting bacterial energy generation, acid production, protein synthesis, and release of antimicrobial molecules. Our study provides novel insights into how amino sugars modify bacterial behavior, information that will be valuable in the design of new technologies to detect and prevent oral infectious diseases.
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Competition and Caries on Enamel of a Dual-Species Biofilm Model with Streptococcus mutans and Streptococcus sanguinis. Appl Environ Microbiol 2020; 86:AEM.01262-20. [PMID: 32826216 DOI: 10.1128/aem.01262-20] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2020] [Accepted: 08/06/2020] [Indexed: 01/07/2023] Open
Abstract
Imbalances within the dental biofilm trigger dental caries, currently considered a dysbiosis and the most prevalent noncommunicable disease. There is still a gap in knowledge about the dynamics of enamel colonization by bacteria from the dental biofilm in caries. The aim, therefore, was to test whether the sequence of enamel colonization by a typically commensal and a cariogenic species modifies biofilm's cariogenicity. Dual-species biofilms of Streptococcus mutans and Streptococcus sanguinis on saliva-coated enamel slabs were inoculated in different sequences: S. mutans followed by S. sanguinis (Sm-Ss), S. sanguinis followed by S. mutans (Ss-Sm), S. mutans and S. sanguinis inoculated at the same time (Sm=Ss), and the single-species controls S. mutans followed by S. mutans (Sm-Sm) and S. sanguinis followed by S. sanguinis (Ss-Ss). Biofilms were exposed to 10% sucrose 3 times per day for 5 days, and the slabs/biofilms were retrieved to assess demineralization, viable cells, biomass, proteins, polysaccharides, and H2O2 production. Compared with Sm-Sm, primary inoculation with S. sanguinis reduced demineralization (P < 0.05). Both Ss-Sm and Sm=Ss sequences showed reduction in biomass, protein, and polysaccharide content (P < 0.05). The highest S. sanguinis viable count and H2O2 production level and the lowest acidogenicity were observed when S. sanguinis colonized enamel before S. mutans (P < 0.05). Initial enamel adherence with commensal biofilms seems to induce more intense competition against more typically cariogenic species, reducing cariogenicity.IMPORTANCE The concept of caries as an ecological disease implies the understanding of the intricate relationships among the populating microorganisms. Under frequent sugar exposure, some bacteria from the dental biofilm develop pathogenic traits that lead to imbalances (dysbiosis). Depending on which microorganism colonizes the dental surface first, different competition strategies may be developed. Studying the interactions in the entire dental biofilm is not an easy task. In this study, therefore, we modeled the interplay among these microorganisms using a caries-inducing species (S. mutans) and a health-associated species (S. sanguinis). Initial enamel adherence with S. sanguinis seems to induce more intense competition against typically caries-inducing species. Besides continuous exposure with sugars, early colonization of the enamel by highly cariogenic species like S. mutans appears to be needed to develop caries lesions as well. Promoting early colonization by health-associated bacteria such as S. sanguinis could help to maintain oral health, delaying dysbiosis.
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Treerat P, Redanz U, Redanz S, Giacaman RA, Merritt J, Kreth J. Synergism between Corynebacterium and Streptococcus sanguinis reveals new interactions between oral commensals. THE ISME JOURNAL 2020; 14:1154-1169. [PMID: 32020052 PMCID: PMC7174362 DOI: 10.1038/s41396-020-0598-2] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/01/2019] [Revised: 01/15/2020] [Accepted: 01/23/2020] [Indexed: 01/28/2023]
Abstract
The oral microbiome engages in a diverse array of highly sophisticated ecological interactions that are crucial for maintaining symbiosis with the host. Streptococci and corynebacteria are among the most abundant oral commensals and their interactions are critical for normal biofilm development. In this study, we discovered that Streptococcus sanguinis specifically responds to the presence of Corynebacterium durum by dramatically altering its chain morphology and improving its overall fitness. By employing gas chromatography-mass spectrometry (GC-MS) analysis, specific fatty acids were identified in C. durum supernatants that are responsible for the observed effect. Membrane vesicles (MVs) containing these fatty acids were isolated from C. durum supernatants and were able to replicate the chain morphology phenotype in S. sanguinis, suggesting MV as a mediator of interspecies interactions. Furthermore, S. sanguinis responds to C. durum lipids by decreasing the expression of key FASII genes involved in fatty acid synthesis. Several of these genes are also essential for the chain elongation phenotype, which implicates a regulatory connection between lipid metabolism and chain elongation. In addition, C. durum was found to affect the growth, cell aggregation, and phagocytosis of S. sanguinis, revealing a complex association of these species that likely supports oral commensal colonization and survival.
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Affiliation(s)
- Puthayalai Treerat
- Department of Restorative Dentistry, School of Dentistry, Oregon Health & Science University (OHSU), Portland, OR, 97239, USA
| | - Ulrike Redanz
- Department of Restorative Dentistry, School of Dentistry, Oregon Health & Science University (OHSU), Portland, OR, 97239, USA
| | - Sylvio Redanz
- Department of Restorative Dentistry, School of Dentistry, Oregon Health & Science University (OHSU), Portland, OR, 97239, USA
- Institute for Medical Microbiology, Virology and Hygiene, University Medicine Rostock, Schillingallee 70, 18057, Rostock, Germany
| | - Rodrigo A Giacaman
- Cariology Unit, Department of Oral Rehabilitation, Faculty of Health Sciences, University of Talca, Talca, Chile
| | - Justin Merritt
- Department of Restorative Dentistry, School of Dentistry, Oregon Health & Science University (OHSU), Portland, OR, 97239, USA
- Department of Molecular Microbiology and Immunology, School of Medicine, Oregon Health & Science University (OHSU), Portland, OR, 97239, USA
| | - Jens Kreth
- Department of Restorative Dentistry, School of Dentistry, Oregon Health & Science University (OHSU), Portland, OR, 97239, USA.
- Department of Molecular Microbiology and Immunology, School of Medicine, Oregon Health & Science University (OHSU), Portland, OR, 97239, USA.
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Pyruvate secretion by oral streptococci modulates hydrogen peroxide dependent antagonism. THE ISME JOURNAL 2020; 14:1074-1088. [PMID: 31988475 PMCID: PMC7174352 DOI: 10.1038/s41396-020-0592-8] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/02/2019] [Revised: 01/14/2020] [Accepted: 01/16/2020] [Indexed: 01/28/2023]
Abstract
Many commensal oral streptococci generate H2O2 via pyruvate oxidase (SpxB) to inhibit the growth of competing bacteria like Streptococcus mutans, a major cariogenic species. In Streptococcus sanguinis SK36 (SK36) and Streptococcus gordonii DL1 (DL1), spxB expression and H2O2 release are subject to carbon catabolite repression by the catabolite control protein A (CcpA). Surprisingly, ccpA deletion mutants of SK36 and DL1 fail to inhibit S. mutans despite their production of otherwise inhibitory levels of H2O2. Using H2O2-deficient spxB deletion mutants of SK36 and DL1, it was subsequently discovered that both strains confer protection in trans to other bacteria when H2O2 is added exogenously. This protective effect depends on the direct detoxification of H2O2 by the release of pyruvate. The pyruvate dependent protective effect is also present in other spxB-encoding streptococci, such as the pneumococcus, but is missing from spxB-negative species like S. mutans. Targeted and transposon-based mutagenesis revealed Nox (putative H2O-forming NADH dehydrogenase) as an essential component required for pyruvate release and oxidative protection, while other genes such as sodA and dps play minor roles. Furthermore, pyruvate secretion is only detectable in aerobic growth conditions at biofilm-like cell densities and is responsive to CcpA-dependent catabolite control. This ability of spxB-encoding streptococci reveals a new facet of the competitive interactions between oral commensals and pathobionts and provides a mechanistic basis for the variable levels of inhibitory potential observed among H2O2-producing strains of commensal oral streptococci.
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Jalal N, Lee SF. The MsrAB reducing pathway of Streptococcus gordonii is needed for oxidative stress tolerance, biofilm formation, and oral colonization in mice. PLoS One 2020; 15:e0229375. [PMID: 32084213 PMCID: PMC7034828 DOI: 10.1371/journal.pone.0229375] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2019] [Accepted: 02/05/2020] [Indexed: 12/22/2022] Open
Abstract
The ability of Streptococcus gordonii to cope with oxidative stress is important for survival and persistence in dental plaque. In this study, we used mutational, phenotypic, and biochemical approaches to characterize the role of a methionine sulfoxide reductase (MsrAB) and proteins encoded by genes in the msrAB operon and an adjacent operon in oxidative stress tolerance in S. gordonii. The results showed that MsrAB and four other proteins encoded in the operons are needed for protection from H2O2 and methionine sulfoxide. These five proteins formed a reducing pathway that was needed for oxidative stress tolerance, biofilm formation, and oral colonization in mice. In the pathway, MsrAB was the enzyme that repaired oxidatively damaged proteins, and the two thioredoxin-like lipoproteins (SdbB and Sgo_1177) and two CcdA proteins were proteins that maintained the catalytic cycle of MsrAB. Consistent with the role in oxidative stress tolerance, the production of MsrAB, SdbB, and Sgo_11777 was induced in aerobic growth and planktonic cells.
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Affiliation(s)
- Naif Jalal
- Department of Microbiology and Immunology, Dalhousie University, Halifax, Nova Scotia, Canada
- Canadian Center for Vaccinology, Dalhousie University, Nova Scotia Health Authority, Izaak Walton Killam Health Centre, Halifax, Nova Scotia, Canada
| | - Song F. Lee
- Department of Microbiology and Immunology, Dalhousie University, Halifax, Nova Scotia, Canada
- Canadian Center for Vaccinology, Dalhousie University, Nova Scotia Health Authority, Izaak Walton Killam Health Centre, Halifax, Nova Scotia, Canada
- Department of Applied Oral Sciences, Faculty of Dentistry, Dalhousie University, Halifax, Nova Scotia, Canada
- * E-mail:
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Wang X, Cai J, Shang N, Zhu L, Shao N, Dong X, Tong H. The carbon catabolite repressor CcpA mediates optimal competence development in Streptococcus oligofermentans through post-transcriptional regulation. Mol Microbiol 2019; 112:552-568. [PMID: 31074889 DOI: 10.1111/mmi.14274] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/07/2019] [Indexed: 11/28/2022]
Abstract
Natural transformation increases the genetic diversity of bacteria, but is costly and must be strictly controlled. We previously found that deletion of ccpA, a key regulator of carbon catabolite repression (CCR), reduced transformation efficiency of Streptococcus oligofermentans, the current work further investigated the regulatory mechanisms of CcpA. The competence operon comCDE is subjected to basal and autoregulatory transcription. A luciferase reporter detected a transcriptional readthrough (TRT) from the upstream tRNAArg into the comCDE operon, which was induced by L -arginine. Insertion of the Escherichia coli T1T2 terminator downstream of tRNAArg abolished TRT, and reduced the basal comCDE transcription by 77% and also the transformation efficiency. Deletion of ccpA increased tRNAArg TRT and tRNAArg -comCDE polycistronic transcript by twofold. An in vitro transcription assay determined that CcpA promoted the transcription termination of tRNAArg TRT, and RNA EMSA and SPR assays detected equal binding affinity of CcpA to both the RNA and DNA of tRNAArg . These results indicate that CcpA controls the basal comCDE transcription by post-transcriptional actions. Overexpression of comDE or its phospho-mimicking mutant comDED58E reduced transformation efficiency, indicating that excessive ComE impairs competence development. CCR-regulated competence was further confirmed by higher tRNAArg TRT but lower transformation efficiency in galactose than in glucose.
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Affiliation(s)
- Xinhui Wang
- State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, No.1 Beichen West Road, Chaoyang District, Beijing, 100101, China.,University of Chinese Academy of Sciences, No.19A Yuquan Road, Shijingshan District, Beijing, 100049, China
| | - Jun Cai
- State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, No.1 Beichen West Road, Chaoyang District, Beijing, 100101, China
| | - Nan Shang
- State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, No.1 Beichen West Road, Chaoyang District, Beijing, 100101, China
| | - Lin Zhu
- State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, No.1 Beichen West Road, Chaoyang District, Beijing, 100101, China
| | - Nana Shao
- State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, No.1 Beichen West Road, Chaoyang District, Beijing, 100101, China
| | - Xiuzhu Dong
- State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, No.1 Beichen West Road, Chaoyang District, Beijing, 100101, China.,University of Chinese Academy of Sciences, No.19A Yuquan Road, Shijingshan District, Beijing, 100049, China
| | - Huichun Tong
- State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, No.1 Beichen West Road, Chaoyang District, Beijing, 100101, China.,University of Chinese Academy of Sciences, No.19A Yuquan Road, Shijingshan District, Beijing, 100049, China
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Amino Sugars Modify Antagonistic Interactions between Commensal Oral Streptococci and Streptococcus mutans. Appl Environ Microbiol 2019; 85:AEM.00370-19. [PMID: 30877119 DOI: 10.1128/aem.00370-19] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2019] [Accepted: 03/12/2019] [Indexed: 02/05/2023] Open
Abstract
N-Acetylglucosamine (GlcNAc) and glucosamine (GlcN) enhance the competitiveness of the laboratory strain DL1 of Streptococcus gordonii against the caries pathogen Streptococcus mutans Here, we examine how amino sugars affect the interaction of five low-passage-number clinical isolates of abundant commensal streptococci with S. mutans by utilizing a dual-species biofilm model. Compared to that for glucose, growth on GlcN or GlcNAc significantly reduced the viability of S. mutans in cocultures with most commensals, shifting the proportions of species. Consistent with these results, production of H2O2 was increased in most commensals when growing on amino sugars, and inhibition of S. mutans by Streptococcus cristatus, Streptococcus oralis, or S. gordonii was enhanced by amino sugars on agar plates. All commensals except S. oralis had higher arginine deiminase activities when grown on GlcN and, in some cases, GlcNAc. In ex vivo biofilms formed using pooled cell-containing saliva (CCS), the proportions of S. mutans were drastically diminished when GlcNAc was the primary carbohydrate. Increased production of H2O2 could account in large part for the inhibitory effects of CCS biofilms. Surprisingly, amino sugars appeared to improve mutacin production by S. mutans on agar plates, suggesting that the commensals have mechanisms to actively subvert antagonism by S. mutans in cocultures. Collectively, these findings demonstrate that amino sugars can enhance the beneficial properties of low-passage-number commensal oral streptococci and highlight their potential for moderating the cariogenicity of oral biofilms.IMPORTANCE Dental caries is driven by dysbiosis of oral biofilms in which dominance by acid-producing and acid-tolerant bacteria results in loss of tooth mineral. Our previous work demonstrated the beneficial effects of amino sugars GlcNAc and GlcN in promoting the antagonistic properties of a health-associated oral bacterium, Streptococcus gordonii, in competition with the major caries pathogen Streptococcus mutans Here, we investigated 5 low-passage-number clinical isolates of the most common streptococcal species to establish how amino sugars may influence the ecology and virulence of oral biofilms. Using multiple in vitro models, including a human saliva-derived microcosm biofilm, experiments showed significant enhancement by at least one amino sugar in the ability of most of these bacteria to suppress the caries pathogen. Therefore, our findings demonstrated the mechanism of action by which amino sugars may affect human oral biofilms to promote health.
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Abstract
With the application of increasingly advanced "omics" technologies to the study of our resident oral microbiota, the presence of a defined, health-associated microbial community has been recognized. Within this community, sanguinis-group streptococci, comprising the closely related Streptococcus sanguinis and Streptococcus gordonii, together with Streptococcus parasanguinis, often predominate. Their ubiquitous and abundant nature reflects the evolution of these bacteria as highly effective colonizers of the oral cavity. Through interactions with host tissues and other microbes, and the capacity to readily adapt to prevailing environmental conditions, sanguinis-group streptococci are able to shape accretion of the oral plaque biofilm and promote development of a microbial community that exists in harmony with its host. Nonetheless, upon gaining access to the blood stream, those very same colonization capabilities can confer upon sanguinis-group streptococci the ability to promote systemic disease. This article focuses on the role of sanguinis-group streptococci as the commensurate commensals, highlighting those aspects of their biology that enable the coordination of health-associated biofilm development. This includes the molecular mechanisms, both synergistic and antagonistic, that underpin adhesion to substrata, intercellular communication, and polymicrobial community formation. As our knowledge of these processes advances, so will the opportunities to exploit this understanding for future development of novel strategies to control oral and extraoral disease.
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Affiliation(s)
- Angela Nobbs
- Bristol Dental School, University of Bristol, Bristol, United Kingdom
| | - Jens Kreth
- Department of Restorative Dentistry, Oregon Health and Science University, Portland, OR 97239
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Abstract
Technological advances in DNA sequencing have provided unprecedented insights into the composition of the oral microbiome in health and disease, and RNA-sequencing and metabolomics-related technologies are beginning to yield information on the activities of these organisms. Importantly, progress in this area has brought the scientific community closer to an understanding of what constitutes a health-associated microbiome and is supporting the notion that the microbiota in healthy sites assumes an active role in promoting health and suppressing the acquisition, persistence, and activities of overt and opportunistic pathogens. It is also becoming clear that a significant impediment to developing a conclusive body of evidence that defines a healthy microbiome and the mechanisms by which beneficial bacteria promote health is that an inherent characteristic of the most abundant members of the oral flora, those that potentially play the greatest roles in health and disease, is intraspecies genomic diversity. In particular, individual isolates of abundant commensal and pathogenic streptococci show tremendous variability in gene content, and this variability manifests in tremendous phenotypic heterogeneity. Analysis of the consequences of this diversity has been complicated by the exquisite sensitivity these bacteria have evolved to environmental inputs, inducing rapid and substantial fluctuations in behaviors, and often only within subpopulations of the organisms. Thus, the conditions under which the oral microbiota is studied can produce widely different results within and between species. Fortunately, continually diminishing costs and ongoing refinements in sequencing and metabolomics are making it practical to study the oral microbiome at a level that will create a sufficiently robust understanding of the functions of individual organisms and reveal the complex interrelationships of these microbes ("the known unknowns") in a way that researchers will be able to engage in the rational design of reliable and economical risk assessments and preventive therapies.
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Affiliation(s)
- R A Burne
- 1 Department of Oral Biology, University of Florida, Gainesville, FL, USA
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Effects of Antimicrobial Peptide GH12 on the Cariogenic Properties and Composition of a Cariogenic Multispecies Biofilm. Appl Environ Microbiol 2018; 84:AEM.01423-18. [PMID: 30341079 DOI: 10.1128/aem.01423-18] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2018] [Accepted: 10/08/2018] [Indexed: 02/05/2023] Open
Abstract
Dental caries is a biofilm-mediated disease that occurs when acidogenic/aciduric bacteria obtain an ecological advantage over commensal species. In previous studies, the effects of the antimicrobial peptide GH12 on planktonic bacteria and monospecies biofilms were confirmed. The objectives of this study were to investigate the effects of GH12 on a cariogenic multispecies biofilm and to preliminarily explain the mechanism. In this biofilm model, Streptococcus mutans ATCC 70061 was the representative of cariogenic bacteria, while Streptococcus gordonii ATCC 35105 and Streptococcus sanguinis JCM 5708 were selected as healthy microbiota. The results showed that GH12 was more effective in suppressing S. mutans than the other two species, with lower MIC and minimal bactericidal concentration (MBC) values among diverse type strains and clinical isolated strains. Therefore, GH12, at no more than 8 mg/liter, was used to selectively suppress S. mutans in the multispecies biofilm. GH12 at 4 mg/liter and 8 mg/liter reduced the cariogenic properties of the multispecies biofilm in biofilm formation, glucan synthesis, and lactic acid production. In addition, GH12 suppressed S. mutans within the multispecies biofilm and changed the bacterial composition. Furthermore, 8 mg/liter GH12 showed a selective bactericidal impact on S. mutans, and GH12 promoted hydrogen peroxide production in S. sanguinis and S. gordonii, which improved their ecological advantages. In conclusion, GH12 inhibited the cariogenic properties and changed the composition of the multispecies biofilm through a two-part mechanism by which GH12 directly suppressed the growth of S. mutans as well as enhanced the ecological competitiveness of S. sanguinis and S. gordonii IMPORTANCE Dental caries is one of the most prevalent chronic infectious diseases worldwide, with substantial economic and quality-of-life impacts. Streptococcus mutans has been considered the principal pathogen of dental caries. To combat dental caries, an antimicrobial peptide, GH12, was designed, and its antibacterial effects on planktonic S. mutans and the monospecies biofilm were confirmed. As etiological concepts of dental caries evolved to include microecosystems, the homeostasis between pathogenic and commensal bacteria and a selective action on cariogenic virulence have increasingly become the focus. The novelty of this research was to study the effects of the antimicrobial peptides on a controlled cariogenic multispecies biofilm model. Notably, the role of an antimicrobial agent in regulating interspecific competition and composition shifts within this multispecies biofilm was investigated. With promising antibacterial and antibiofilm properties, the use of GH12 might be of importance in preventing and controlling caries and other dental infections.
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Redanz S, Cheng X, Giacaman RA, Pfeifer CS, Merritt J, Kreth J. Live and let die: Hydrogen peroxide production by the commensal flora and its role in maintaining a symbiotic microbiome. Mol Oral Microbiol 2018; 33:337-352. [PMID: 29897662 DOI: 10.1111/omi.12231] [Citation(s) in RCA: 69] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/11/2018] [Indexed: 02/05/2023]
Abstract
The majority of commensal oral streptococci are able to generate hydrogen peroxide (H2 O2 ) during aerobic growth, which can diffuse through the cell membrane and inhibit competing species in close proximity. Competing H2 O2 production is mainly dependent upon the pyruvate oxidase SpxB, and to a lesser extent the lactate oxidase LctO, both of which are important for energy generation in aerobic environments. Several studies point to a broad impact of H2 O2 production in the oral environment, including a potential role in biofilm homeostasis, signaling, and interspecies interactions. Here, we summarize the current research regarding oral streptococcal H2 O2 generation, resistance mechanisms, and the ecological impact of H2 O2 production. We also discuss the potential therapeutic utility of H2 O2 for the prevention/treatment of dysbiotic diseases as well as its potential role as a biomarker of oral health.
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Affiliation(s)
- Sylvio Redanz
- Department of Restorative Dentistry, Oregon Health and Science University, Portland, Oregon
| | - Xingqun Cheng
- The State Key Laboratory of Oral Diseases & National Clinical Research Center for Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu, China.,The Department of Cariology and Endodontics, West China Hospital of Stomatology, Sichuan University, Chengdu, China
| | - Rodrigo A Giacaman
- Cariology Unit, Department of Oral Rehabilitation and Interdisciplinary Excellence Research Program on Healthy Aging (PIEI-ES), University of Talca, Talca, Chile
| | - Carmen S Pfeifer
- Department of Restorative Dentistry, Oregon Health and Science University, Portland, Oregon
| | - Justin Merritt
- Department of Restorative Dentistry, Oregon Health and Science University, Portland, Oregon
| | - Jens Kreth
- Department of Restorative Dentistry, Oregon Health and Science University, Portland, Oregon
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24
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Distinct Regulatory Role of Carbon Catabolite Protein A (CcpA) in Oral Streptococcal spxB Expression. J Bacteriol 2018; 200:JB.00619-17. [PMID: 29378884 DOI: 10.1128/jb.00619-17] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2017] [Accepted: 01/12/2018] [Indexed: 12/14/2022] Open
Abstract
Pyruvate oxidase (SpxB)-dependent H2O2 production is under the control of carbon catabolite protein A (CcpA) in the oral species Streptococcus sanguinis and Streptococcus gordonii Interestingly, both species react differently to the presence of the preferred carbohydrate source glucose. S. gordonii CcpA-dependent regulation of spxB follows classical carbon catabolite repression. Conversely, spxB expression in S. sanguinis is not influenced by glucose but is repressed by CcpA. Here, we constructed strains expressing the heterologous versions of CcpA or the spxB promoter region to learn if the distinct regulation of spxB expression is transferable from S. gordonii to S. sanguinis and vice versa. While cross-species binding of CcpA to the spxB promoter is conserved in vitro, we were unable to swap the species-specific regulation. This suggests that a regulatory mechanism upstream of CcpA most likely is responsible for the observed difference in spxB expression. Moreover, the overall ecological significance of differential spxB regulation in the presence of various glucose concentrations was tested with additional oral streptococcus isolates and demonstrated that carbohydrate-dependent and carbohydrate-independent mechanisms exist to control expression of spxB in the oral biofilm. Overall, our data demonstrate the unexpected finding that metabolic pathways between two closely related oral streptococcal species can be regulated differently despite an exceptionally high DNA sequence identity.IMPORTANCE Polymicrobial diseases are the result of interactions among the residential microbes, which can lead to a dysbiotic community. Streptococcus sanguinis and Streptococcus gordonii are considered commensal species that are present in the healthy dental biofilm. Both species are able to produce significant amounts of H2O2 via the enzymatic action of the pyruvate oxidase SpxB. H2O2 is able to inhibit species associated with oral diseases. SpxB and its gene-regulatory elements present in both species are highly conserved. Nonetheless, a differential response to the presence of glucose was observed. Here, we investigate the mechanisms that lead to this differential response. Detailed knowledge of the regulatory mechanisms will aid in a better understanding of oral disease development and how to prevent dysbiosis.
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Plasticity of the Pyruvate Node Modulates Hydrogen Peroxide Production and Acid Tolerance in Multiple Oral Streptococci. Appl Environ Microbiol 2018; 84:AEM.01697-17. [PMID: 29079629 DOI: 10.1128/aem.01697-17] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2017] [Accepted: 10/19/2017] [Indexed: 02/05/2023] Open
Abstract
Commensal Streptococcus sanguinis and Streptococcus gordonii are pioneer oral biofilm colonizers. Characteristic for both is the SpxB-dependent production of H2O2, which is crucial for inhibiting competing biofilm members, especially the cariogenic species Streptococcus mutans H2O2 production is strongly affected by environmental conditions, but few mechanisms are known. Dental plaque pH is one of the key parameters dictating dental plaque ecology and ultimately oral health status. Therefore, the objective of the current study was to characterize the effects of environmental pH on H2O2 production by S. sanguinis and S. gordoniiS. sanguinis H2O2 production was not found to be affected by moderate changes in environmental pH, whereas S. gordonii H2O2 production declined markedly in response to lower pH. Further investigation into the pyruvate node, the central metabolic switch modulating H2O2 or lactic acid production, revealed increased lactic acid levels for S. gordonii at pH 6. The bias for lactic acid production at pH 6 resulted in concomitant improvement in the survival of S. gordonii at low pH and seems to constitute part of the acid tolerance response of S. gordonii Differential responses to pH similarly affect other oral streptococcal species, suggesting that the observed results are part of a larger phenomenon linking environmental pH, central metabolism, and the capacity to produce antagonistic amounts of H2O2IMPORTANCE Oral biofilms are subject to frequent and dramatic changes in pH. S. sanguinis and S. gordonii can compete with caries- and periodontitis-associated pathogens by generating H2O2 Therefore, it is crucial to understand how S. sanguinis and S. gordonii adapt to low pH and maintain their competitiveness under acid stress. The present study provides evidence that certain oral bacteria respond to environmental pH changes by tuning their metabolic output in favor of lactic acid production, to increase their acid survival, while others maintain their H2O2 production at a constant level. The differential control of H2O2 production provides important insights into the role of environmental conditions for growth competition of the oral flora.
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Huang X, Browngardt CM, Jiang M, Ahn SJ, Burne RA, Nascimento MM. Diversity in Antagonistic Interactions between Commensal Oral Streptococci and Streptococcus mutans. Caries Res 2017; 52:88-101. [PMID: 29258070 PMCID: PMC5828942 DOI: 10.1159/000479091] [Citation(s) in RCA: 59] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2016] [Accepted: 06/29/2017] [Indexed: 12/28/2022] Open
Abstract
Arginine metabolism via the arginine deiminase system (ADS) of oral bacteria generates ammonia, which can increase the pH of oral biofilms and decrease the risk for dental caries. Antagonistic interactions between ADS-positive and cariogenic bacteria in oral biofilms may be an important ecological determinant of caries. This study investigated the antagonistic potential and mechanisms of clinical isolates of arginolytic streptococci on and by Streptococcus mutans UA159, a well-characterized cariogenic human isolate. Low-passage isolates of Streptococcus gordonii, Streptococcus sanguinis, Streptococcus parasanguinis, Streptococcus australis, and Streptococcus cristatus inhibited the growth of S. mutans to various degrees when they were inoculated on growth media first or simultaneously with S. mutans. The antagonistic effects of arginolytic strains against S. mutans and the production of H2O2 by these strains were enhanced during growth in a less-rich medium or when galactose was substituted for glucose as the primary carbohydrate source. Pyruvate oxidase was the dominant pathway for H2O2 production by arginolytic strains, but lactate oxidase activity was also detected in some strains of S. gordonii and S. cristatus. UA159 inhibited the growth of all tested arginolytic strains when inoculated first, especially in aerobic conditions. However, the antagonistic effects of S. mutans on certain strains of S. gordonii and S. australis were not observed during anaerobic growth in the presence of arginine. Thus, arginolytic commensal streptococci may have a synergistically positive impact on the ecology of oral biofilms by moderating biofilm pH while antagonizing the growth and virulence of caries pathogens.
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Affiliation(s)
- Xuelian Huang
- Division of General Dentistry, Eastman Institute for Oral Health, University of Rochester, Rochester, NY, USA
| | | | - Min Jiang
- Department of Epidemiology and Biostatistics, West China School of Public Health, Sichuan University, Chengdu, Sichuan, China
| | - Sang-Joon Ahn
- Department of Oral Biology, College of Dentistry, University of Florida, Gainesville, FL, USA
| | - Robert A. Burne
- Department of Oral Biology, College of Dentistry, University of Florida, Gainesville, FL, USA
| | - Marcelle M. Nascimento
- Department of Restorative Dental Sciences, Division of Operative Dentistry, College of Dentistry, University of Florida, Gainesville, FL, USA
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27
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Wen ZT, Liao S, Bitoun JP, De A, Jorgensen A, Feng S, Xu X, Chain PSG, Caufield PW, Koo H, Li Y. Streptococcus mutans Displays Altered Stress Responses While Enhancing Biofilm Formation by Lactobacillus casei in Mixed-Species Consortium. Front Cell Infect Microbiol 2017; 7:524. [PMID: 29326887 PMCID: PMC5742344 DOI: 10.3389/fcimb.2017.00524] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2017] [Accepted: 12/11/2017] [Indexed: 12/13/2022] Open
Abstract
Like Streptococcus mutans, lactobacilli are commonly isolated from carious sites, although their exact role in caries development remains unclear. This study used mixed-species models to analyze biofilm formation by major groups of oral lactobacilli, including L. casei, L. fermentum, L. rhamnosus, L. salivarius ssp. salivarius, and L. gasseri. The results showed that lactobacilli did not form good biofilms when grown alone, although differences existed between different species. When grown together with S. mutans, biofilm formation by L. gasseri and L. rhamnosus was increased by 2-log (P < 0.001), while biofilms by L. fermentum reduced by >1-log (P < 0.001). L. casei enhanced biofilm formation by ~2-log when grown with S. mutans wild-type, but no such effects were observed with S. mutans deficient of glucosyltransferase GtfB and adhesin P1. Both S. mutans and L. casei in dual-species enhanced resistance to acid killing with increases of survival rate by >1-log (P < 0.001), but drastically reduced the survival rates following exposure to hydrogen peroxide (P < 0.001), as compared to the respective mono-species cultures. When analyzed by RNA-seq, more than 134 genes were identified in S. mutans in dual-species with L. casei as either up- or down-regulated when compared to those grown alone. The up-regulated genes include those for superoxide dismutase, NADH oxidase, and members of the mutanobactin biosynthesis cluster. Among the down-regulated genes were those for GtfB and alternative sigma factor SigX. These results further suggest that interactions between S. mutans and oral lactobacilli are species-specific and may have significant impact on cariogenic potential of the community.
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Affiliation(s)
- Zezhang T Wen
- Center of Oral and Craniofacial Biology, Louisiana State University Health Sciences Center, New Orleans, LA, United States.,Department of Comprehensive Dentistry and Biomaterials, Louisiana State University Health Sciences Center, New Orleans, LA, United States.,Department of Microbiology, Immunology and Parasitology, Louisiana State University Health Sciences Center, New Orleans, LA, United States
| | - Sumei Liao
- Center of Oral and Craniofacial Biology, Louisiana State University Health Sciences Center, New Orleans, LA, United States
| | - Jacob P Bitoun
- Center of Oral and Craniofacial Biology, Louisiana State University Health Sciences Center, New Orleans, LA, United States
| | - Arpan De
- Department of Comprehensive Dentistry and Biomaterials, Louisiana State University Health Sciences Center, New Orleans, LA, United States
| | - Ashton Jorgensen
- Department of Comprehensive Dentistry and Biomaterials, Louisiana State University Health Sciences Center, New Orleans, LA, United States
| | - Shihai Feng
- Genome Science Group, Bioscience Division, Los Alamos National Laboratory, Los Alamos, NM, United States
| | - Xiaoming Xu
- Department of Comprehensive Dentistry and Biomaterials, Louisiana State University Health Sciences Center, New Orleans, LA, United States
| | - Patrick S G Chain
- Genome Science Group, Bioscience Division, Los Alamos National Laboratory, Los Alamos, NM, United States
| | - Page W Caufield
- Basic Science and Craniofacial Biology, New York University College of Dentistry, New York, NY, United States
| | - Hyun Koo
- Biofilm Research Labs, Levy Center for Oral Health, Department of Orthodontics, School of Dental Medicine, University of Pennsylvania, Philadelphia, PA, United States
| | - Yihong Li
- Basic Science and Craniofacial Biology, New York University College of Dentistry, New York, NY, United States
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28
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Chen Z, Mashburn-Warren L, Merritt J, Federle MJ, Kreth J. Interference of a speB 5' untranslated region partial deletion with mRNA degradation in Streptococcus pyogenes. Mol Oral Microbiol 2017; 32:390-403. [PMID: 28371435 PMCID: PMC10030001 DOI: 10.1111/omi.12181] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/26/2017] [Indexed: 01/28/2023]
Abstract
The 5' untranslated region (5' UTR) of an mRNA molecule embeds important determinants that modify its stability and translation efficiency. In Streptococcus pyogenes, a strict human pathogen, a gene encoding a secreted protease (speB) has a large 5' UTR with unknown functions. Here we describe that a partial deletion of the speB 5' UTR caused a general accumulation of mRNA in the stationary phase, and that the mRNA accumulation was due to retarded mRNA degradation. The phenotype was observed in several M serotypes harboring the partial deletion of the speB 5' UTR. The phenotype was triggered by the production of the truncated speB 5' UTR, but not by the disruption of the intact speB 5' UTR. RNase Y, a major endoribonuclease, was previously shown to play a central role in bulk mRNA turnover in stationary phase. However, in contrast to our expectations, we observed a weaker interaction between the truncated speB 5' UTR and RNase Y compared with the wild-type, which suggests that other unidentified RNA degrading components are required for the pleiotropic effects observed from the speB UTR truncation. Our study demonstrates how S. pyogenes uses distinct mRNA degradation schemes in exponential and stationary growth phases.
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Affiliation(s)
- Z Chen
- Department of Microbiology and Immunology, University of Oklahoma Health Sciences Center, Oklahoma City, OK, USA
| | - L Mashburn-Warren
- Center for Microbial Pathogenesis, The Research Institute, Nationwide Children's Hospital, Columbus, OH, USA
| | - J Merritt
- Department of Restorative Dentistry, Oregon Health and Science University, Portland, OR, USA
| | - M J Federle
- Center for Biomolecular Sciences, Department of Medicinal Chemistry and Pharmacognosy, College of Pharmacy, University of Illinois at Chicago, Chicago, IL, USA
| | - J Kreth
- Department of Restorative Dentistry, Oregon Health and Science University, Portland, OR, USA
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29
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Keke Z, Xuedong Z, Xin X. [The origin of hydrogen peroxide in oral cavity and its role in oral microecology balance]. HUA XI KOU QIANG YI XUE ZA ZHI = HUAXI KOUQIANG YIXUE ZAZHI = WEST CHINA JOURNAL OF STOMATOLOGY 2017; 35:215-220. [PMID: 28682556 DOI: 10.7518/hxkq.2017.02.020] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Hydrogen peroxide, an important antimicrobial agent in oral cavity, plays a significant role in the balance of oral microecology. At the early stage of biofilm formation, about 80% of the detected initial colonizers belong to the genus Streptococcus. These oral streptococci use different oxidase to produce hydrogen peroxide. Recent studies showed that the produced hydrogen peroxide plays a critical role in modulating oral microecology. Hydrogen peroxide modulates biofilm development attributed to its growth inhibitory nature. Hydrogen peroxide production is closely associated with extracellular DNA(eDNA) release from microbe and the development of its competent cell which are critical for biofilm development and also serves as source for horizontal gene transfer. Microbe also can reduce the damage to themselves through several detoxification mechanisms. Moreover, hydrogen peroxide is also involved in the regulation of interactions between oral microorganisms and host. Taken together, hydrogen peroxide is an imperative ecological factor that contributes to the microbial equilibrium in the oral cavity. Here we will give a brief review of both the origin and the function in the oral microecology balance of hydrogen peroxide.
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Affiliation(s)
- Zhang Keke
- State Key Laboratory of Oral Diseases, National Clinical Research Center for Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu 610041, China
| | - Zhou Xuedong
- State Key Laboratory of Oral Diseases, National Clinical Research Center for Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu 610041, China
| | - Xu Xin
- State Key Laboratory of Oral Diseases, National Clinical Research Center for Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu 610041, China
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30
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Joshi VS, Kreth J, Koley D. Pt-Decorated MWCNTs-Ionic Liquid Composite-Based Hydrogen Peroxide Sensor To Study Microbial Metabolism Using Scanning Electrochemical Microscopy. Anal Chem 2017; 89:7709-7718. [PMID: 28613833 PMCID: PMC6261441 DOI: 10.1021/acs.analchem.7b01677] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Hydrogen peroxide (H2O2) is a highly relevant metabolite in many biological processes, including the oral microbiome. To study this metabolite, we developed a 25 μm diameter, highly sensitive, nonenzymatic H2O2 sensor with a detection limit of 250 nM and a broad linear range of 250 nM to 7 mM. The sensor used the synergistic activity of the catalytically active Pt nanoparticles on a high surface area multiwalled carbon nanotube and conducting ionic liquid matrix to achieve high sensitivity (2.4 ± 0.24 mA cm-2 mM-1) for H2O2 oxidation. The unique composite allowed us to miniaturize the sensor and couple it with a Pt electrode (25 μm diameter each) for use as a dual scanning electrochemical microscopy probe. We could detect 65 ± 10 μM H2O2 produced by Streptococcus gordonii (Sg) in a simulated biofilm at 50 μm above its surface in the presence of 1 mM glucose and artificial saliva solution (pH 7.2 at 37 °C). Because of its high stability and low detection limit, the sensor showed a promising chemical image of H2O2 produced by Sg biofilms. We were also able to detect 30 μM H2O2 at 50 μm above the biofilm in the presence of the H2O2-decomposing salivary lactoperoxidase and thiocyanate, which would not otherwise be possible using an existing H2O2 assay. Thus, this sensor can potentially find applications in the study of other important biological processes in a complex matrix where circumstances demand a low detection limit in a compact space.
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Affiliation(s)
- Vrushali S Joshi
- Department of Chemistry, Oregon State University, Corvallis, OR 97331, USA
| | - Jens Kreth
- Department of Restorative Dentistry, Oregon Health & Science University, Portland, OR USA
| | - Dipankar Koley
- Department of Chemistry, Oregon State University, Corvallis, OR 97331, USA
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31
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Kreth J, Giacaman RA, Raghavan R, Merritt J. The road less traveled - defining molecular commensalism with Streptococcus sanguinis. Mol Oral Microbiol 2017; 32:181-196. [PMID: 27476770 PMCID: PMC5288394 DOI: 10.1111/omi.12170] [Citation(s) in RCA: 59] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/26/2016] [Indexed: 12/15/2022]
Abstract
The commensal oral microbial flora has evolved with the human host to support colonization of the various intraoral sites without triggering a significant immune response. In exchange, the commensal microbes provide critical protection against invading pathogens. The intrinsic ability of the oral flora to create a symbiotic microbial community with the host can be disturbed, selecting for the overgrowth of a dysbiotic community that can result in dental diseases, such as caries and periodontitis. Although the mechanisms of molecular pathogenesis in oral diseases are well characterized, much less is known about the molecular mechanisms used by the commensal flora to maintain oral health. Here we focus on the commensal species Streptococcus sanguinis, which is found in abundance in the early oral biofilm and is strongly correlated with oral health. Streptococcus sanguinis exhibits a variety of features that make it ideally suited as a model organism to explore the molecular basis for commensalism. As such, this review will describe our current mechanistic understanding of S. sanguinis commensalism and speculate upon its molecular traits that may be exploitable to maintain or restore oral health under conditions that would otherwise lead to disease.
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Affiliation(s)
- Jens Kreth
- Department of Restorative Dentistry, Oregon Health and Science University, Portland, OR, USA
| | - Rodrigo A. Giacaman
- Cariology Unit, Department of Oral Rehabilitation and Interdisciplinary Excellence Research Program on Healthy Aging (PIEI-ES), University of Talca, Talca, Chile
| | - Rahul Raghavan
- Department of Biology and Center for Life in Extreme Environments, Portland State University, Portland, OR, USA
| | - Justin Merritt
- Department of Restorative Dentistry, Oregon Health and Science University, Portland, OR, USA
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32
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Knaus UG, Hertzberger R, Pircalabioru GG, Yousefi SPM, Branco dos Santos F. Pathogen control at the intestinal mucosa - H 2O 2 to the rescue. Gut Microbes 2017; 8:67-74. [PMID: 28080210 PMCID: PMC5341913 DOI: 10.1080/19490976.2017.1279378] [Citation(s) in RCA: 42] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
Intestinal infections are a global challenge, connected to malnutrition and inadequate hygiene in developing countries, and to expanding antibiotic resistance in developed countries. In general, a healthy host is capable of fighting off gut pathogens or at least to recover from infections quickly. The underlying protective mechanism, termed colonization resistance, is provided by indigenous commensal communities (microbiota) that are shaped and aided by the host's epithelial and innate immune system. Commensal-pathogen interactions are governed by competition for a suitable niche for replication and stable colonization, nutrient availability, species-specific alterations of the metabolic environment, changes in oxygen tension and release of chemicals and proteinaceous toxins (bacteriocins). This protective intestinal milieu is further reinforced by antimicrobial factors and chemicals secreted by the epithelial barrier, by dendritic cell sensing and by homeostasis between T-cell subsets (Treg/Th17) in the lamina propria. The 3 players (host-microbiota-pathogen) communicate via direct interactions or secreted factors. Our recent manuscript illustrates that reactive oxygen species (ROS) are an integral part of colonization resistance and should be considered an interkingdom antivirulence strategy.
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Affiliation(s)
- Ulla G. Knaus
- Conway Institute, School of Medicine, University College Dublin, Dublin, Ireland
| | - Rosanne Hertzberger
- Swammerdam Institute for Life Sciences, University of Amsterdam, Amsterdam, The Netherlands
| | | | - S. Parsa M. Yousefi
- Swammerdam Institute for Life Sciences, University of Amsterdam, Amsterdam, The Netherlands
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Blanchette KA, Shenoy AT, Milner J, Gilley RP, McClure E, Hinojosa CA, Kumar N, Daugherty SC, Tallon LJ, Ott S, King SJ, Ferreira DM, Gordon SB, Tettelin H, Orihuela CJ. Neuraminidase A-Exposed Galactose Promotes Streptococcus pneumoniae Biofilm Formation during Colonization. Infect Immun 2016; 84:2922-32. [PMID: 27481242 PMCID: PMC5038079 DOI: 10.1128/iai.00277-16] [Citation(s) in RCA: 43] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2016] [Accepted: 07/21/2016] [Indexed: 01/26/2023] Open
Abstract
Streptococcus pneumoniae is an opportunistic pathogen that colonizes the nasopharynx. Herein we show that carbon availability is distinct between the nasopharynx and bloodstream of adult humans: glucose is absent from the nasopharynx, whereas galactose is abundant. We demonstrate that pneumococcal neuraminidase A (NanA), which cleaves terminal sialic acid residues from host glycoproteins, exposed galactose on the surface of septal epithelial cells, thereby increasing its availability during colonization. We observed that S. pneumoniae mutants deficient in NanA and β-galactosidase A (BgaA) failed to form biofilms in vivo despite normal biofilm-forming abilities in vitro Subsequently, we observed that glucose, sucrose, and fructose were inhibitory for biofilm formation, whereas galactose, lactose, and low concentrations of sialic acid were permissive. Together these findings suggested that the genes involved in biofilm formation were under some form of carbon catabolite repression (CCR), a regulatory network in which genes involved in the uptake and metabolism of less-preferred sugars are silenced during growth with preferred sugars. Supporting this notion, we observed that a mutant deficient in pyruvate oxidase, which converts pyruvate to acetyl-phosphate under non-CCR-inducing growth conditions, was unable to form biofilms. Subsequent comparative transcriptome sequencing (RNA-seq) analyses of planktonic and biofilm-grown pneumococci showed that metabolic pathways involving the conversion of pyruvate to acetyl-phosphate and subsequently leading to fatty acid biosynthesis were consistently upregulated during diverse biofilm growth conditions. We conclude that carbon availability in the nasopharynx impacts pneumococcal biofilm formation in vivo Additionally, biofilm formation involves metabolic pathways not previously appreciated to play an important role.
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Affiliation(s)
- Krystle A Blanchette
- Department of Microbiology and Immunology, The University of Texas Health Science Center at San Antonio, San Antonio, Texas, USA
| | - Anukul T Shenoy
- Department of Microbiology and Immunology, The University of Texas Health Science Center at San Antonio, San Antonio, Texas, USA Department of Microbiology, The University of Alabama at Birmingham, Birmingham, Alabama, USA
| | - Jeffrey Milner
- Department of Microbiology, The University of Alabama at Birmingham, Birmingham, Alabama, USA
| | - Ryan P Gilley
- Department of Microbiology and Immunology, The University of Texas Health Science Center at San Antonio, San Antonio, Texas, USA
| | - Erin McClure
- Department of Microbiology and Immunology, Institute for Genome Sciences, University of Maryland School of Medicine, Baltimore, Maryland, USA
| | - Cecilia A Hinojosa
- Department of Microbiology and Immunology, The University of Texas Health Science Center at San Antonio, San Antonio, Texas, USA
| | - Nikhil Kumar
- Department of Microbiology and Immunology, Institute for Genome Sciences, University of Maryland School of Medicine, Baltimore, Maryland, USA
| | - Sean C Daugherty
- Department of Microbiology and Immunology, Institute for Genome Sciences, University of Maryland School of Medicine, Baltimore, Maryland, USA
| | - Luke J Tallon
- Department of Microbiology and Immunology, Institute for Genome Sciences, University of Maryland School of Medicine, Baltimore, Maryland, USA
| | - Sandra Ott
- Department of Microbiology and Immunology, Institute for Genome Sciences, University of Maryland School of Medicine, Baltimore, Maryland, USA
| | - Samantha J King
- Center for Microbial Pathogenesis, The Research Institute at Nationwide Children's Hospital, Columbus, Ohio, USA Department of Pediatrics, The Ohio State University, Columbus, Ohio, USA
| | - Daniela M Ferreira
- Department of Clinical Sciences, Liverpool School of Tropical Medicine, Liverpool, United Kingdom
| | - Stephen B Gordon
- Department of Clinical Sciences, Liverpool School of Tropical Medicine, Liverpool, United Kingdom
| | - Hervé Tettelin
- Department of Microbiology and Immunology, Institute for Genome Sciences, University of Maryland School of Medicine, Baltimore, Maryland, USA
| | - Carlos J Orihuela
- Department of Microbiology and Immunology, The University of Texas Health Science Center at San Antonio, San Antonio, Texas, USA Department of Microbiology, The University of Alabama at Birmingham, Birmingham, Alabama, USA
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Amino Sugars Enhance the Competitiveness of Beneficial Commensals with Streptococcus mutans through Multiple Mechanisms. Appl Environ Microbiol 2016; 82:3671-82. [PMID: 27084009 DOI: 10.1128/aem.00637-16] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2016] [Accepted: 04/11/2016] [Indexed: 12/17/2022] Open
Abstract
UNLABELLED Biochemical and genetic aspects of the metabolism of the amino sugars N-acetylglucosamine (GlcNAc) and glucosamine (GlcN) by commensal oral streptococci and the effects of these sugars on interspecies competition with the dental caries pathogen Streptococcus mutans were explored. Multiple S. mutans wild-type isolates displayed long lag phases when transferred from glucose-containing medium to medium with GlcNAc as the primary carbohydrate source, but commensal streptococci did not. Competition in liquid coculture or dual-species biofilms between S. mutans and Streptococcus gordonii showed that S. gordonii was particularly dominant when the primary carbohydrate was GlcN or GlcNAc. Transcriptional and enzymatic assays showed that the catabolic pathway for GlcNAc was less highly induced in S. mutans than in S. gordonii Exposure to H2O2, which is produced by S. gordonii and antagonizes the growth of S. mutans, led to reduced mRNA levels of nagA and nagB in S. mutans When the gene for the transcriptional regulatory NagR was deleted in S. gordonii, the strain produced constitutively high levels of nagA (GlcNAc-6-P deacetylase), nagB (GlcN-6-P deaminase), and glmS (GlcN-6-P synthase) mRNA. Similar to NagR of S. mutans (NagRSm), the S. gordonii NagR protein (NagRSg) could bind to consensus binding sites (dre) in the nagA, nagB, and glmS promoter regions of S. gordonii Notably, NagRSg binding was inhibited by GlcN-6-P, but G-6-P had no effect, unlike for NagRSm This study expands the understanding of amino sugar metabolism and NagR-dependent gene regulation in streptococci and highlights the potential for therapeutic applications of amino sugars to prevent dental caries. IMPORTANCE Amino sugars are abundant in the biosphere, so the relative efficiency of particular bacteria in a given microbiota to metabolize these sources of carbon and nitrogen might have a profound impact on the ecology of the community. Our investigation reveals that several oral commensal bacteria have a much greater capacity to utilize amino sugars than the dental pathogen Streptococcus mutans and that the ability of the model commensal Streptococcus gordonii to compete against S. mutans is substantively enhanced by the presence of amino sugars commonly found in the oral cavity. The mechanisms underlying the greater capacity and competitive enhancements of the commensal are shown to depend on how the genes for the catabolic enzymes are regulated, the role of the allosteric modulators affecting such regulation, and the ability of amino sugars to enhance certain activities of the commensal that are antagonistic to S. mutans.
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Abstract
Pathogenic bacteria must contend with immune systems that actively restrict the availability of nutrients and cofactors, and create a hostile growth environment. To deal with these hostile environments, pathogenic bacteria have evolved or acquired virulence determinants that aid in the acquisition of nutrients. This connection between pathogenesis and nutrition may explain why regulators of metabolism in nonpathogenic bacteria are used by pathogenic bacteria to regulate both metabolism and virulence. Such coordinated regulation is presumably advantageous because it conserves carbon and energy by aligning synthesis of virulence determinants with the nutritional environment. In Gram-positive bacterial pathogens, at least three metabolite-responsive global regulators, CcpA, CodY, and Rex, have been shown to coordinate the expression of metabolism and virulence genes. In this chapter, we discuss how environmental challenges alter metabolism, the regulators that respond to this altered metabolism, and how these regulators influence the host-pathogen interaction.
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A Highly Arginolytic Streptococcus Species That Potently Antagonizes Streptococcus mutans. Appl Environ Microbiol 2016; 82:2187-201. [PMID: 26826230 DOI: 10.1128/aem.03887-15] [Citation(s) in RCA: 83] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2015] [Accepted: 01/26/2016] [Indexed: 01/08/2023] Open
Abstract
The ability of certain oral biofilm bacteria to moderate pH through arginine metabolism by the arginine deiminase system (ADS) is a deterrent to the development of dental caries. Here, we characterize a novel Streptococcus strain, designated strain A12, isolated from supragingival dental plaque of a caries-free individual. A12 not only expressed the ADS pathway at high levels under a variety of conditions but also effectively inhibited growth and two intercellular signaling pathways of the dental caries pathogen Streptococcus mutans. A12 produced copious amounts of H2O2 via the pyruvate oxidase enzyme that were sufficient to arrest the growth of S. mutans. A12 also produced a protease similar to challisin (Sgc) of Streptococcus gordonii that was able to block the competence-stimulating peptide (CSP)-ComDE signaling system, which is essential for bacteriocin production by S. mutans. Wild-type A12, but not an sgc mutant derivative, could protect the sensitive indicator strain Streptococcus sanguinis SK150 from killing by the bacteriocins of S. mutans. A12, but not S. gordonii, could also block the XIP (comX-inducing peptide) signaling pathway, which is the proximal regulator of genetic competence in S. mutans, but Sgc was not required for this activity. The complete genome sequence of A12 was determined, and phylogenomic analyses compared A12 to streptococcal reference genomes. A12 was most similar to Streptococcus australis and Streptococcus parasanguinis but sufficiently different that it may represent a new species. A12-like organisms may play crucial roles in the promotion of stable, health-associated oral biofilm communities by moderating plaque pH and interfering with the growth and virulence of caries pathogens.
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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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Rudney JD, Jagtap PD, Reilly CS, Chen R, Markowski TW, Higgins L, Johnson JE, Griffin TJ. Protein relative abundance patterns associated with sucrose-induced dysbiosis are conserved across taxonomically diverse oral microcosm biofilm models of dental caries. MICROBIOME 2015; 3:69. [PMID: 26684897 PMCID: PMC4684605 DOI: 10.1186/s40168-015-0136-z] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/28/2015] [Accepted: 11/25/2015] [Indexed: 05/30/2023]
Abstract
BACKGROUND The etiology of dental caries is multifactorial, but frequent consumption of free sugars, notably sucrose, appears to be a major factor driving the supragingival microbiota in the direction of dysbiosis. Recent 16S rRNA-based studies indicated that caries-associated communities were less diverse than healthy supragingival plaque but still displayed considerable taxonomic diversity between individuals. Metagenomic studies likewise have found that healthy oral sites from different people were broadly similar with respect to gene function, even though there was an extensive individual variation in their taxonomic profiles. That pattern may also extend to dysbiotic communities. In that case, shifts in community-wide protein relative abundance might provide better biomarkers of dysbiosis that can be achieved through taxonomy alone. RESULTS In this study, we used a paired oral microcosm biofilm model of dental caries to investigate differences in community composition and protein relative abundance in the presence and absence of sucrose. This approach provided large quantities of protein, which facilitated deep metaproteomic analysis. Community composition was evaluated using 16S rRNA sequencing and metaproteomic approaches. Although taxonomic diversity was reduced by sucrose pulsing, considerable inter-subject variation in community composition remained. By contrast, functional analysis using the SEED ontology found that sucrose induced changes in protein relative abundance patterns for pathways involving glycolysis, lactate production, aciduricity, and ammonia/glutamate metabolism that were conserved across taxonomically diverse dysbiotic oral microcosm biofilm communities. CONCLUSIONS Our findings support the concept of using function-based changes in protein relative abundance as indicators of dysbiosis. Our microcosm model cannot replicate all aspects of the oral environment, but the deep level of metaproteomic analysis it allows makes it suitable for discovering which proteins are most consistently abundant during dysbiosis. It then may be possible to define biomarkers that could be used to detect at-risk tooth surfaces before the development of overt carious lesions.
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Affiliation(s)
- Joel D Rudney
- Department of Diagnostic and Biological Sciences, School of Dentistry, University of Minnesota, 515 Delaware St. SE, Minneapolis, MN, 55455, USA.
| | - Pratik D Jagtap
- Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, 321 Church Street SE, Minneapolis, MN, 55455, USA.
- Center for Mass Spectrometry and Proteomics, University of Minnesota, 1479 Gortner Avenue, Saint Paul, MN, 55108, USA.
| | - Cavan S Reilly
- Division of Biostatistics, School of Public Health, University of Minnesota, 420 Delaware St. SE, Minneapolis, MN, 55455, USA.
| | - Ruoqiong Chen
- Department of Diagnostic and Biological Sciences, School of Dentistry, University of Minnesota, 515 Delaware St. SE, Minneapolis, MN, 55455, USA.
| | - Todd W Markowski
- Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, 321 Church Street SE, Minneapolis, MN, 55455, USA.
- Center for Mass Spectrometry and Proteomics, University of Minnesota, 1479 Gortner Avenue, Saint Paul, MN, 55108, USA.
| | - LeeAnn Higgins
- Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, 321 Church Street SE, Minneapolis, MN, 55455, USA.
- Center for Mass Spectrometry and Proteomics, University of Minnesota, 1479 Gortner Avenue, Saint Paul, MN, 55108, USA.
| | - James E Johnson
- University of Minnesota Supercomputing Institute, 117 Pleasant St. SE, Minneapolis, MN, 55455, USA.
| | - Timothy J Griffin
- Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, 321 Church Street SE, Minneapolis, MN, 55455, USA.
- Center for Mass Spectrometry and Proteomics, University of Minnesota, 1479 Gortner Avenue, Saint Paul, MN, 55108, USA.
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Leclerc J, Rosenfeld E, Trainini M, Martin B, Meuric V, Bonnaure-Mallet M, Baysse C. The Cytochrome bd Oxidase of Porphyromonas gingivalis Contributes to Oxidative Stress Resistance and Dioxygen Tolerance. PLoS One 2015; 10:e0143808. [PMID: 26629705 PMCID: PMC4668044 DOI: 10.1371/journal.pone.0143808] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2015] [Accepted: 11/10/2015] [Indexed: 11/18/2022] Open
Abstract
Porphyromonas gingivalis is an etiologic agent of periodontal disease in humans. The disease is associated with the formation of a mixed oral biofilm which is exposed to oxygen and environmental stress, such as oxidative stress. To investigate possible roles for cytochrome bd oxidase in the growth and persistence of this anaerobic bacterium inside the oral biofilm, mutant strains deficient in cytochrome bd oxidase activity were characterized. This study demonstrated that the cytochrome bd oxidase of Porphyromonas gingivalis, encoded by cydAB, was able to catalyse O2 consumption and was involved in peroxide and superoxide resistance, and dioxygen tolerance.
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Affiliation(s)
- Julia Leclerc
- EA1254 Microbiologie—Risques Infectieux, University of Rennes1, Rennes, France
| | - Eric Rosenfeld
- UMR CNRS 7266 LIENSs, University of La Rochelle, La Rochelle, France
| | - Mathieu Trainini
- EA1254 Microbiologie—Risques Infectieux, University of Rennes1, Rennes, France
| | - Bénédicte Martin
- EA1254 Microbiologie—Risques Infectieux, University of Rennes1, Rennes, France
| | - Vincent Meuric
- EA1254 Microbiologie—Risques Infectieux, University of Rennes1, Rennes, France
- UMR CNRS 7266 LIENSs, University of La Rochelle, La Rochelle, France
- CHU Rennes, Rennes, France
| | - Martine Bonnaure-Mallet
- EA1254 Microbiologie—Risques Infectieux, University of Rennes1, Rennes, France
- UMR CNRS 7266 LIENSs, University of La Rochelle, La Rochelle, France
- CHU Rennes, Rennes, France
| | - Christine Baysse
- EA1254 Microbiologie—Risques Infectieux, University of Rennes1, Rennes, France
- * E-mail:
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Schanche M, Avershina E, Dotterud C, Øien T, Storrø O, Johnsen R, Rudi K. High-Resolution Analyses of Overlap in the Microbiota Between Mothers and Their Children. Curr Microbiol 2015; 71:283-90. [PMID: 26044992 DOI: 10.1007/s00284-015-0843-5] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2015] [Accepted: 04/18/2015] [Indexed: 12/01/2022]
Abstract
Understanding the transmission of the human microbiota from mother to child is of major importance. Although we are gaining knowledge using 16S rRNA gene analyses, the resolution of this gene is not sufficient to determine transmission patterns. We therefore developed an Illumina deep sequencing approach targeting the 16-23S rRNA Internal Transcribed Spacer (ITS) for high-resolution microbiota analyses. Using this approach, we analyzed the composition and potential mother to child transmission patterns of the microbiota (milk and stool) in a longitudinal cohort of 20 mother/child pairs. Our results show overlap in the infant stool microbiota with both mother's milk and stool, and that the overlap with stool increases with age. We found an Operational Taxonomic Unit resembling Streptococcus gordonii as the most widespread colonizer of both mothers and their children. In conclusion, the increased resolution of 16-23S rRNA ITS deep sequencing revealed new knowledge about potential transmission patterns of human-associated bacteria.
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Affiliation(s)
- Melissa Schanche
- Department of Chemistry, Biotechnology and Food Science, University of Life Sciences, Ås, Norway
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Moye ZD, Zeng L, Burne RA. Fueling the caries process: carbohydrate metabolism and gene regulation by Streptococcus mutans. J Oral Microbiol 2014; 6:24878. [PMID: 25317251 PMCID: PMC4157138 DOI: 10.3402/jom.v6.24878] [Citation(s) in RCA: 97] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2014] [Revised: 08/08/2014] [Accepted: 08/11/2014] [Indexed: 11/17/2022] Open
Abstract
The nature of the oral cavity and host behaviors has mandated that the oral microbiota evolve mechanisms for coping with environmental fluctuations, especially changes in the type and availability of carbohydrates. In the case of human dental caries, the presence of excess carbohydrates is often responsible for altering the local environment to be more favorable for species associated with the initiation and progression of disease, including Streptococcus mutans. Some of the earliest endeavors to understand how cariogenic species respond to environmental perturbations were carried out using chemostat cultivation, which provides fine control over culture conditions and bacterial behaviors. The development of genome-scale methodologies has allowed for the combination of sophisticated cultivation technologies with genome-level analysis to more thoroughly probe how bacterial pathogens respond to environmental stimuli. Recent investigations in S. mutans and other closely related streptococci have begun to reveal that carbohydrate metabolism can drastically impact pathogenic potential and highlight the important influence that nutrient acquisition has on the success of pathogens; inside and outside of the oral cavity. Collectively, research into pathogenic streptococci, which have evolved in close association with the human host, has begun to unveil the essential nature of careful orchestration of carbohydrate acquisition and catabolism to allow the organisms to persist and, when conditions allow, initiate or worsen disease.
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Affiliation(s)
- Zachary D Moye
- Department of Oral Biology, College of Dentistry, University of Florida, Gainesville, FL, USA
| | - Lin Zeng
- Department of Oral Biology, College of Dentistry, University of Florida, Gainesville, FL, USA
| | - Robert A Burne
- Department of Oral Biology, College of Dentistry, University of Florida, Gainesville, FL, USA
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Cavalcanti YW, Bertolini MM, da Silva WJ, Del-Bel-Cury AA, Tenuta LMA, Cury JA. A three-species biofilm model for the evaluation of enamel and dentin demineralization. BIOFOULING 2014; 30:579-588. [PMID: 24730462 DOI: 10.1080/08927014.2014.905547] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Although Streptococcus mutans biofilms have been useful for evaluating the cariogenic potential of dietary carbohydrates and the effects of fluoride on dental demineralization, a more appropriate biofilm should be developed to demonstrate the influence of other oral bacteria on cariogenic biofilms. This study describes the development and validation of a three-species biofilm model comprising Streptococcus mutans, Actinomyces naeslundii, and Streptococcus gordonii for the evaluation of enamel and dentin demineralization after cariogenic challenges and fluoride exposure. Single- or three-species biofilms were developed on dental substrata for 96 h, and biofilms were exposed to feast and famine episodes. The three-species biofilm model produced a large biomass, mostly comprising S. mutans (41%) and S. gordonii (44%), and produced significant demineralization in the dental substrata, although enamel demineralization was decreased by fluoride treatment. The findings indicate that the three-species biofilm model may be useful for evaluating the cariogenic potential of dietary carbohydrates other than sucrose and determining the effects of fluoride on dental substrata.
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Affiliation(s)
- Yuri Wanderley Cavalcanti
- a Department of Prosthodontics and Periodontology, Piracicaba Dental School , University of Campinas , Piracicaba , SP , Brazil
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Carvalho SM, Farshchi Andisi V, Gradstedt H, Neef J, Kuipers OP, Neves AR, Bijlsma JJE. Pyruvate oxidase influences the sugar utilization pattern and capsule production in Streptococcus pneumoniae. PLoS One 2013; 8:e68277. [PMID: 23844180 PMCID: PMC3701046 DOI: 10.1371/journal.pone.0068277] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2012] [Accepted: 06/02/2013] [Indexed: 11/18/2022] Open
Abstract
Pyruvate oxidase is a key function in the metabolism and lifestyle of many lactic acid bacteria and its activity depends on the presence of environmental oxygen. In Streptococcus pneumoniae the protein has been suggested to play a major role in metabolism and has been implicated in virulence, oxidative stress survival and death in stationary phase. Under semi-aerobic conditions, transcriptomic and metabolite profiling analysis of a spxB mutant grown on glucose showed minor changes compared to the wild type, apart from the significant induction of two operons involved in carbohydrate uptake and processing. This induction leads to a change in the sugar utilization capabilities of the bacterium, as indicated by the analysis of the growth profiles of the D39 parent and spxB mutant on alternative carbohydrates. Metabolic analysis and growth experiments showed that inactivation of SpxB has no effect on the glucose fermentation pattern, except under aerobic conditions. More importantly, we show that mutation of spxB results in the production of increased amounts of capsule, the major virulence factor of S. pneumoniae. Part of this increase can be attributed to induction of capsule operon (cps) transcription. Therefore, we propose that S. pneumoniae utilizes pyruvate oxidase as an indirect sensor of the oxygenation of the environment, resulting in the adaption of its nutritional capability and the amount of capsule to survive in the host.
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Affiliation(s)
- Sandra M. Carvalho
- Instituto de Tecnologia Química e Biológica, Universidade Nova de Lisboa, Oeiras, Portugal
| | - Vahid Farshchi Andisi
- Department of Medical Microbiology, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands
| | - Henrik Gradstedt
- Department of Medical Microbiology, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands
| | - Jolanda Neef
- Department of Medical Microbiology, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands
| | - Oscar P. Kuipers
- Department of Molecular Genetics, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, Groningen, The Netherlands
| | - Ana R. Neves
- Instituto de Tecnologia Química e Biológica, Universidade Nova de Lisboa, Oeiras, Portugal
| | - Jetta J. E. Bijlsma
- Department of Medical Microbiology, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands
- * E-mail:
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Xu Y, Kreth J. Role of LytF and AtlS in eDNA release by Streptococcus gordonii. PLoS One 2013; 8:e62339. [PMID: 23638042 PMCID: PMC3634736 DOI: 10.1371/journal.pone.0062339] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2012] [Accepted: 03/20/2013] [Indexed: 02/07/2023] Open
Abstract
Extracellular DNA (eDNA) is an important component of the biofilm matrix produced by many bacteria. In general, the release of eDNA is associated with the activity of muralytic enzymes leading to obvious cell lysis. In the Gram-positive oral commensal Streptococcus gordonii, eDNA release is dependent on pyruvate oxidase generated hydrogen peroxide (H2O2). Addition of H2O2 to cells grown under conditions non-permissive for H2O2 production causes eDNA release. Furthermore, eDNA release is maximal under aerobic growth conditions known to induce pyruvate oxidase gene expression and H2O2 production. Obvious cell lysis, however, does not occur. Two enzymes have been recently associated with eDNA release in S. gordonii. The autolysin AtlS and the competence regulated murein hydrolase LytF. In the present report, we investigated the role of both proteins in the H2O2 dependent eDNA release process. Single and double mutants in the respective genes for LytF and AtlS released less eDNA under normal growth conditions, but the AtlS mutant was still inducible for eDNA release by external H2O2. Moreover, we showed that the AtlS mutation interfered with the ability of S. gordonii to produce eDNA release inducing amounts of H2O2. Our data support a role of LytF in the H2O2 eDNA dependent release of S. gordonii as part of the competence stress pathway responding to oxidative stress.
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Affiliation(s)
- Yifan Xu
- Department of Microbiology and Immunology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma, United States of America
- Department of Surgical Oncology, The First Hospital of China Medical University, Shenyang, PR China
| | - Jens Kreth
- Department of Microbiology and Immunology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma, United States of America
- College of Dentistry, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma, United States of America
- * E-mail:
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The role of hydrogen peroxide in environmental adaptation of oral microbial communities. OXIDATIVE MEDICINE AND CELLULAR LONGEVITY 2012; 2012:717843. [PMID: 22848782 PMCID: PMC3405655 DOI: 10.1155/2012/717843] [Citation(s) in RCA: 99] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/10/2012] [Accepted: 05/11/2012] [Indexed: 11/17/2022]
Abstract
Oral streptococci are able to produce growth-inhibiting amounts of hydrogen peroxide (H(2)O(2)) as byproduct of aerobic metabolism. Several recent studies showed that the produced H(2)O(2) is not a simple byproduct of metabolism but functions in several aspects of oral bacterial biofilm ecology. First, the release of DNA from cells is closely associated to the production of H(2)O(2) in Streptococcus sanguinis and Streptococcus gordonii. Extracellular DNA is crucial for biofilm development and stabilization and can also serve as source for horizontal gene transfer between oral streptococci. Second, due to the growth inhibiting nature of H(2)O(2), H(2)O(2) compatible species associate with the producers. H(2)O(2) production therefore might help in structuring the initial biofilm development. On the other hand, the oral environment harbors salivary peroxidases that are potent in H(2)O(2) scavenging. Therefore, the effects of biofilm intrinsic H(2)O(2) production might be locally confined. However, taking into account that 80% of initial oral biofilm constituents are streptococci, the influence of H(2)O(2) on biofilm development and environmental adaptation might be under appreciated in current research.
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Two gene clusters coordinate galactose and lactose metabolism in Streptococcus gordonii. Appl Environ Microbiol 2012; 78:5597-605. [PMID: 22660715 DOI: 10.1128/aem.01393-12] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Streptococcus gordonii is an early colonizer of the human oral cavity and an abundant constituent of oral biofilms. Two tandemly arranged gene clusters, designated lac and gal, were identified in the S. gordonii DL1 genome, which encode genes of the tagatose pathway (lacABCD) and sugar phosphotransferase system (PTS) enzyme II permeases. Genes encoding a predicted phospho-β-galactosidase (LacG), a DeoR family transcriptional regulator (LacR), and a transcriptional antiterminator (LacT) were also present in the clusters. Growth and PTS assays supported that the permease designated EII(Lac) transports lactose and galactose, whereas EII(Gal) transports galactose. The expression of the gene for EII(Gal) was markedly upregulated in cells growing on galactose. Using promoter-cat fusions, a role for LacR in the regulation of the expressions of both gene clusters was demonstrated, and the gal cluster was also shown to be sensitive to repression by CcpA. The deletion of lacT caused an inability to grow on lactose, apparently because of its role in the regulation of the expression of the genes for EII(Lac), but had little effect on galactose utilization. S. gordonii maintained a selective advantage over Streptococcus mutans in a mixed-species competition assay, associated with its possession of a high-affinity galactose PTS, although S. mutans could persist better at low pHs. Collectively, these results support the concept that the galactose and lactose systems of S. gordonii are subject to complex regulation and that a high-affinity galactose PTS may be advantageous when S. gordonii is competing against the caries pathogen S. mutans in oral biofilms.
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CcpA-dependent carbohydrate catabolite repression regulates galactose metabolism in Streptococcus oligofermentans. J Bacteriol 2012; 194:3824-32. [PMID: 22609925 DOI: 10.1128/jb.00156-12] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Streptococcus oligofermentans is an oral commensal that inhibits the growth of the caries pathogen Streptococcus mutans by producing copious amounts of H(2)O(2) and that grows faster than S. mutans on galactose. In this study, we identified a novel eight-gene galactose (gal) operon in S. oligofermentans that was comprised of lacABCD, lacX, and three genes encoding a galactose-specific transporter. Disruption of lacA caused more growth reduction on galactose than mutation of galK, a gene in the Leloir pathway, indicating that the principal role of this operon is in galactose metabolism. Diauxic growth was observed in cultures containing glucose and galactose, and a luciferase reporter fusion to the putative gal promoter demonstrated 12-fold repression of the operon expression by glucose but was induced by galactose, suggesting a carbon catabolite repression (CCR) control in galactose utilization. Interestingly, none of the single-gene mutations in the well-known CCR regulators ccpA and manL affected diauxic growth, although the operon expression was upregulated in these mutants in glucose. A double mutation of ccpA and manL eliminated glucose repression of galactose utilization, suggesting that these genes have parallel functions in regulating gal operon expression and mediating CCR. Electrophoretic mobility shift assays demonstrated binding of CcpA to the putative catabolite response element motif in the promoter regions of the gal operon and manL, suggesting that CcpA regulates CCR through direct regulation of the transcription of the gal operon and manL. This provides the first example of oral streptococci using two parallel CcpA-dependent CCR pathways in controlling carbohydrate metabolism.
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Liu Y, Wu L, Wu F, Chu L, Liu X, Xia K, Wang Y. Interspecies competition and inhibition within the oral microbial flora: environmental factors influence the inhibition of Streptococcus mutans by Streptococcus oligofermentans. Eur J Oral Sci 2012; 120:179-84. [DOI: 10.1111/j.1600-0722.2012.00957.x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Function of the pyruvate oxidase-lactate oxidase cascade in interspecies competition between Streptococcus oligofermentans and Streptococcus mutans. Appl Environ Microbiol 2012; 78:2120-7. [PMID: 22287002 DOI: 10.1128/aem.07539-11] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Complex interspecies interactions occur constantly between oral commensals and the opportunistic pathogen Streptococcus mutans in dental plaque. Previously, we showed that oral commensal Streptococcus oligofermentans possesses multiple enzymes for H(2)O(2) production, especially lactate oxidase (Lox), allowing it to out-compete S. mutans. In this study, through extensive biochemical and genetic studies, we identified a pyruvate oxidase (pox) gene in S. oligofermentans. A pox deletion mutant completely lost Pox activity, while ectopically expressed pox restored activity. Pox was determined to produce most of the H(2)O(2) in the earlier growth phase and log phase, while Lox mainly contributed to H(2)O(2) production in stationary phase. Both pox and lox were expressed throughout the growth phase, while expression of the lox gene increased by about 2.5-fold when cells entered stationary phase. Since lactate accumulation occurred to a large degree in stationary phase, the differential Pox- and Lox-generated H(2)O(2) can be attributed to differential gene expression and substrate availability. Interestingly, inactivation of pox causes a dramatic reduction in H(2)O(2) production from lactate, suggesting a synergistic action of the two oxidases in converting lactate into H(2)O(2). In an in vitro two-species biofilm experiment, the pox mutant of S. oligofermentans failed to inhibit S. mutans even though lox was active. In summary, S. oligofermentans develops a Pox-Lox synergy strategy to maximize its H(2)O(2) formation so as to win the interspecies competition.
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