Lactobacilli Postbiotics reduce biofilm formation and alter transcription of virulence genes of Aggregatibacter actinomycetemcomitans
AbstractPeriodontitis is characterized by a dysbiotic microbial community and treatment strategies include the reestablishment of symbiosis by reducing pathogens abundance.Aggregatibacter actinomycetemcomitans (Aa) is frequently associated with rapidly progressing periodontitis. Since the oral ecosystem may be affected by metabolic ‐end‐products of bacteria, we evaluated the effect of soluble compounds released by probiotic lactobacilli, known as postbiotics, on Aa biofilm and expression of virulence‐associated genes. Cell‐free pH‐neutralized supernatants (CFS) ofLactobacillus rhamnosus Lr32,L. rhamnosus HN001,La...
Source: Molecular Oral Microbiology - December 29, 2020 Category: Microbiology Authors: Karin Hitomi Ishikawa, Manuela Rocha Bueno, Dione Kawamoto, Maria Regina Lorenzetti Simionato, Marcia Pinto Alves Mayer Tags: ORIGINAL ARTICLE Source Type: research

Activity of Ligustrum robustum (Roxb.) Blume extract against the biofilm formation and exopolysaccharide synthesis of Streptococcus mutans
AbstractLigustrum robustum (Roxb.) Blume is utilized as a traditional Chinese herbal tea with various health benefits and protective effects.Streptococcus mutans is an important cariogenic oral bacteria species. The present study aimed to assess the influence ofLigustrum. robustum extract (LRE) on the biofilm formation ofS.mutans and the mechanism of its action, as well as to identify its chemical components. For chemical identification, HPLC ‐MS and NMR were applied and four identified phytochemicals were reported (Ligurobustoside B, Ligurobustoside N, Ligurobustoside J and Ligurobustoside C). The dose‐dependent (0.5 ...
Source: Molecular Oral Microbiology - December 14, 2020 Category: Microbiology Authors: Zhong Zhang, Jumei Zeng, Xuedong Zhou, Qianda Xu, Chenghui Li, Yiduo Liu, Chaoliang Zhang, Liu Wang, Weicai Zeng, Yuqing Li Tags: ORIGINAL ARTICLE Source Type: research

Examination of gene expression in saliva samples from COVID ‐19 patients to study the host defense response against SARS‐CoV‐2 in the oral cavity
AbstractInfection with severe acute respiratory syndrome coronavirus 2 (SARS ‐CoV‐2) causes coronavirus disease 2019 (COVID‐19), which presents with respiratory symptoms including fever, sore throat, cough and congestion, suggesting that infection of the oral cavity and nasopharynx (ONP) is an obligate step in its pathogenesis. Consistent with this role in the initial infection, oral and nasopharyngeal epithelial cells express the SARS‐CoV‐2 spike protein receptor, angiotensin‐converting enzyme 2 (ACE2) (1), and RT‐PCR based testing can routinely detect SARS‐CoV‐2 RNA within both the nasal and buccal tiss...
Source: Molecular Oral Microbiology - December 8, 2020 Category: Microbiology Authors: Gill Diamond, Erika L. Figgins, Tanya Robinson, Michal Senitko, George E. Abraham, Haley B. Williams, Meredith Sloan, Anna Owings, Hannah Laird, Yilianys Pride, Kenneth J. Wilson, Mohammad Hasan, Adam Parker, Sarah C. Glover Tags: LETTER TO THE EDITOR Source Type: research

Aggregatibacter actinomycetemcomitans induces a proatherosclerotic response in human endothelial cells in a three ‐dimensional collagen scaffold model
This study characterizes a three ‐dimensional model with human coronary artery endothelial cells on three‐dimensional (HCAEC‐3D) type I collagen scaffolds to evaluate whether infection withAggregatibacter actinomycetemcomitans induces a proinflammatory response associated with atherosclerosis. The HCAEC ‐3D culture was physicochemically characterized in regard to biocompatibility and barrier function. Then, the culture was infected withA. actinomycetemcomitans strain ATCC 29522 at multiplicities of infection (MOIs) of 1:1, 1:10, and 1:100. Cultures without infection and stimulated withA. actinomycetemcomitans lipop...
Source: Molecular Oral Microbiology - December 7, 2020 Category: Microbiology Authors: Maria A. Torres, Diego F. Gualtero, Gloria I. Lafaurie, Marta R. Fontanilla Tags: ORIGINAL ARTICLE Source Type: research

Issue Information
Molecular Oral Microbiology, Volume 35, Issue 6, Page i-iii, December 2020. (Source: Molecular Oral Microbiology)
Source: Molecular Oral Microbiology - December 6, 2020 Category: Microbiology Tags: ISSUE INFORMATION Source Type: research

Modified SHI medium supports growth of a disease ‐state subgingival polymicrobial community in vitro
AbstractDeveloping a laboratory model of oral polymicrobial communities is essential for in vitro studies of the transition from healthy to diseased oral plaque. SHI medium is an enriched growth medium capable of supporting in vitro biofilms with similar diversity to healthy supragingival inocula; however, this medium does not maintain the diversity of gram ‐negative bacteria more associated with subgingival plaque. Here, we systematically modified SHI medium components to investigate the impacts of varying nutrients and develop a medium capable of supporting a specific disease‐state subgingival community. A diseased s...
Source: Molecular Oral Microbiology - December 3, 2020 Category: Microbiology Authors: Eleanor I. Lamont, Archita Gadkari, Kristopher A. Kerns, Thao T. To, Diane Daubert, Georgios Kotsakis, Batbileg Bor, Xuesong He, Jeffrey S. McLean Tags: ORIGINAL ARTICLE Source Type: research

Development of an FhbB based chimeric vaccinogen that elicits antibodies that block Factor H binding and cleavage by the periopathogen Treponema denticola
This study is the first to extend this approach to the development of a preventive or therapeutic vaccine (or monoclonal Ab) for periodontal disease. (Source: Molecular Oral Microbiology)
Source: Molecular Oral Microbiology - November 20, 2020 Category: Microbiology Authors: Nathaniel S. OBier, Dhara T. Patel, Lee D. Oliver, Daniel P. Miller, Richard T. Marconi Tags: ORIGINAL ARTICLE Source Type: research

Modified SHI ‐medium supports growth of a disease‐state subgingival polymicrobial community in vitro
SummaryDeveloping a laboratory model of oral polymicrobial communities is essential forin vitro studies of the transition from healthy to diseased oral plaque. SHI ‐medium is an enriched growth medium capable of supportingin vitro biofilms with similar diversity to healthy supragingival inocula; however, this medium does not maintain the diversity of gram ‐negative bacteria more associated with subgingival plaque. Here, we systematically modified SHI‐medium components to investigate the impacts of varying nutrients and develop a medium capable of supporting a specific disease‐state subgingival community. A periodon...
Source: Molecular Oral Microbiology - November 11, 2020 Category: Microbiology Authors: Eleanor I. Lamont, Archita Gadkari, Kristopher A. Kerns, Thao T. To, Diane Daubert, Georgios Kotsakis, Batbileg Bor, Xuesong He, Jeffrey S. McLean Tags: ORIGINAL ARTICLE Source Type: research

A double ‐edged sword: Role of butyrate in the oral cavity and the gut
AbstractButyrate, a four ‐carbon short‐chain fatty acid (SCFA), is a metabolite of anaerobic bacteria. Butyrate has primarily been described as an energy substance in the studies on the digestive tract, the largest microorganism reservoir in the human body. The multiple mechanisms of its protective function in the gut a nd on underlying diseases (including metabolic diseases, diseases of the nervous system, and osteoporosis) via interaction with intestinal epithelial cells and immune cells have been well documented. There are many butyrogenic bacteria in the oral cavity as well. As essential components of the oral micr...
Source: Molecular Oral Microbiology - November 5, 2020 Category: Microbiology Authors: Xiaoyuan Guan, Wenjing Li, Huanxin Meng Tags: REVIEW ARTICLE Source Type: research

Periodontal Pathogens ’ strategies disarm neutrophils to promote dysregulated inflammation.
SummaryPeriodontitis is an irreversible, chronic inflammatory disease where inflammophilic pathogenic microbial communities accumulate in the gingival crevice. Neutrophils are a major component of the innate host response against bacterial challenge, and under homeostatic conditions, their microbicidal functions typically protect the host against periodontitis. However, a number of periodontal pathogens developed survival strategies to evade neutrophil microbicidal functions while promoting inflammation, which provides a source of nutrients for bacterial growth. Research on periodontal pathogens has largely focused on a fe...
Source: Molecular Oral Microbiology - October 31, 2020 Category: Microbiology Authors: Irina Miralda, Silvia M Uriarte Tags: REVIEW ARTICLE Source Type: research

Towards defining the outer membrane proteome of Porphyromonas gingivalis
SummaryPorphyromonas gingivalis is a Gram ‐negative anaerobic pathogen found in subgingival plaque associated with progressive periodontitis. Proteins associated with the outer membrane (OM) of Gram‐negative pathogens are particularly important for understanding virulence and for developing vaccines. The aim of this study was to establi sh a reliable list of outer membrane associated proteins (Omps) for this organism. Starting with a list of 99 experimentally determined Omps, several bioinformatics tools were used to predict a further 52 proteins, leading to a predicted OM proteome of 151 proteins. The tools used inclu...
Source: Molecular Oral Microbiology - October 30, 2020 Category: Microbiology Authors: Paul D. Veith, Dhana G. Gorasia, Eric C. Reynolds Tags: ORIGINAL ARTICLE Source Type: research

Enhanced Biofilm Formation of Streptococcus gordonii with Lipoprotein Deficiency
In this study, we investigated the role of lipoproteins ofS. gordonii in the bacterial biofilm formation using its lipoprotein ‐deficient strain (Δlgt). TheS. gordonii Δlgt exhibited increased biofilm formation on the human dentin slices or on the polystyrene surfaces compared to the wild ‐type strain, while its growth rate did not differ from that of the wild‐type. In addition, theS. gordonii Δlgt strain exhibited the enhanced mRNA expression of LuxS and AI ‐2 production, which is known to be a positive regulator of biofilm formation, compared to the wild‐type. Concordantly, the augmented biofi...
Source: Molecular Oral Microbiology - October 15, 2020 Category: Microbiology Authors: Ok ‐Jin Park, Solmin Jung, Taehwan Park, A Reum Kim, Dongwook Lee, Hyun Jung Ji, Ho Seong Seo, Cheol‐Heui Yun, Seung Hyun Han Tags: ORIGINAL ARTICLE Source Type: research

Dipeptidyl ‐peptidases: Key enzymes producing entry forms of extracellular proteins in asaccharolytic periodontopathic bacterium Porphyromonas gingivalis
We present here an overview of dipeptide production byP. gingivalis mediated by dipeptidyl ‐peptidases (DPPs), e.g., DPP4, DPP5, DPP7, and DPP11, serine exopeptidases localized in periplasm, which release dipeptides from the N‐terminus of polypeptides. Additionally, two other exopeptidases, acylpeptidyl‐oligopeptidase (AOP) and prolyl tripeptidyl‐peptidase A (PTP‐A), which liber ate N‐terminal acylated di‐/tri‐peptides and tripeptides with Pro at the third position, respectively, provide polypeptides in an acceptable form for DPPs. Hence, a large fraction of dipeptides is produced from nutritional polypepti...
Source: Molecular Oral Microbiology - October 12, 2020 Category: Microbiology Authors: Takayuki K. Nemoto, Yuko Ohara Nemoto Tags: INVITED REVIEW Source Type: research

Multiple Factors are Involved in Regulation of Extracellular Membrane Vesicle Biogenesis in Streptococcus mutans
In this study, functional genomics, along within vitro biofilm models, was used to identify factors that regulate MV biogenesis. Our results showed that when added to growth medium, MVs significantly enhanced biofilm formation byS. mutans, especially during growth in sucrose. This effect occurred in the presence and absence of added human saliva. Functional genomics revealed several genes, includingsfp, which have a major effect onS. mutans MVs. InBacillus sp.sfp encodes a 4 ’‐phosphopantetheinyl transferase that contributes to surfactin biosynthesis and impacts vesiculogenesis. InS. mutans, sfp resides within the ...
Source: Molecular Oral Microbiology - October 10, 2020 Category: Microbiology Authors: Zezhang T. Wen, Ashton N. Jorgensen, Xiaochang Huang, Kassapa Ellepola, Lynne Chapman, Hui Wu, L. Jeannine Brady Tags: ORIGINAL ARTICLE Source Type: research

Dipeptidyl ‐peptidases: Key enzymes producing entry forms of extracellular proteins in asaccharolytic periodontopathic bacterium Porphyromonas gingivalis
We present here an overview of dipeptide production byP. gingivalis mediated by dipeptidyl ‐peptidases (DPPs), e.g., DPP4, DPP5, DPP7, and DPP11, serine exopeptidases localized in periplasm, which release dipeptides from the N‐terminus of polypeptides. Additionally, two other exopeptidases, acylpeptidyl‐oligopeptidase (AOP) and prolyl tripeptidyl‐peptidase A (PTP‐A), which liber ate N‐terminal acylated di‐/tri‐peptides and tripeptides with Pro at the third position, respectively, provide polypeptides in an acceptable form for DPPs. Hence, a large fraction of dipeptides is produced from nutritional polypepti...
Source: Molecular Oral Microbiology - October 1, 2020 Category: Microbiology Authors: Takayuki K. Nemoto, Yuko Ohara Nemoto Tags: INVITED REVIEW ARTICLE Source Type: research

Identification of Streptococcus mutans genes involved in fluoride resistance by screening of a transposon mutant library
We describe here the construction and characterization of a mariner ‐based transposon system designed to be used inS. mutans, which is also potentially applicable to other streptococci. To identify genetic determinants of fluoride resistance inS. mutans, we constructed a library ofS. mutans transposon insertion mutants and screened this library to identify mutants exhibiting fluoride resistance phenotype. Two mutants were found to carry transposon insertion in two different genetic loci (smu.396 andsmu.1291c) respectively. Our subsequent genetic study indicates the fluoride resistant phenotype for the mutant with the ins...
Source: Molecular Oral Microbiology - September 29, 2020 Category: Microbiology Authors: Jie Yu, Yaqi Wang, Dongmei Han, Wei Cao, Lanyan Zheng, Zhoujie Xie, Hao Liu Tags: ORIGINAL ARTICLE Source Type: research

Issue Information
Molecular Oral Microbiology, Volume 35, Issue 5, Page i-iii, October 2020. (Source: Molecular Oral Microbiology)
Source: Molecular Oral Microbiology - September 25, 2020 Category: Microbiology Tags: ISSUE INFORMATION Source Type: research

Polyamines in the Virulence of Bacterial Pathogens of Respiratory Tract
SummaryPolyamines are positively charged hydrocarbons that are essential for the growth and cellular maintenance in prokaryotes and eukaryotes. Polyamines have been demonstrated to play a role in bacterial pathogenicity and biofilm formation. However, the role of extracellular polyamines as a signaling molecule in the regulation of virulence is not investigated in detail. The bacterial pathogens residing in the respiratory tract remains asymptomatic for an extended period; however, the factors that lead to symptomatic behavior is poorly understood. Further investigation to understand the relation between the host ‐secret...
Source: Molecular Oral Microbiology - September 25, 2020 Category: Microbiology Authors: Rajashri Banerji, Poonam Kanojiya, Amrita Patil, Sunil D. Saroj Tags: REVIEW ARTICLE Source Type: research

Platelet plug formation in whole blood is enhanced in the presence of Porphyromonas gingivalis
SummaryPorphyromonas gingivalis is a gram ‐negative anaerobic bacterium and an etiologic agent of adult periodontitis. By inducing a dysbiotic state within the host microbiota it contributes to a chronic inflammatory environment in the oral cavity. Under some circumstances, the oral bacteria may gain access to systemic circulation. While the most widely recognized function of platelets is to reduce hemorrhage in case of vascular damage, it is known that platelets are also involved in the hematologic responses to bacterial infections. Some pathogenic bacteria can interact with platelets, triggering their activation and ag...
Source: Molecular Oral Microbiology - September 17, 2020 Category: Microbiology Authors: William A. Chen, Hansel M. Fletcher, Joseph Gheorghe, Udochukwu Oyoyo, Danilo S. Boskovic Tags: ORIGINAL ARTICLE Source Type: research

The enterococcal PASTA kinase: a sentinel for cell envelope stress
AbstractEnterococci are Gram ‐positive, opportunistic pathogens that reside throughout the gastrointestinal tracts of most terrestrial organisms. Enterococci are resistant to many antibiotics, which makes enterococcal infections difficult to treat. Enterococci are also particularly hardy bacteria that can tolerate a variety o f environmental stressors. Understanding how enterococci sense and respond to the extracellular environment to enact adaptive biological responses may identify new targets that can be exploited for development of treatments for enterococcal infections. Bacterial eukaryotic‐like serine/threonine ki...
Source: Molecular Oral Microbiology - September 17, 2020 Category: Microbiology Authors: Du šanka Djorić, Nicole E. Minton, Christopher J. Kristich Tags: INVITED REVIEW Source Type: research

Comprehensive profiling of protein lysine acetylation and its overlap with lysine succinylation in the Porphyromonas gingivalis fimbriated strain ATCC 33277
This study provides a significant beginning for further investigating the role of Kac and Ksuc in the pathogenicity ofP. gingivalis. (Source: Molecular Oral Microbiology)
Source: Molecular Oral Microbiology - September 15, 2020 Category: Microbiology Authors: Jumei Zeng, Leng Wu, Qiushi Chen, Lingyun Wang, Wei Qiu, Xin Zheng, Xiaoming Yin, Jie Liu, Yan Ren, Yuqing Li Tags: ORIGINAL ARTICLE Source Type: research

Role of the RprY Response Regulator in P. gingivalis Community Development and Virulence
In this study we examined cross phosphorylation of RprY on tyrosine residues and its importance for RprY function. We show that RprY reacts with phosphotyrosine antibodies, and a tyrosine (Y) resi due at position 41 is predicted to be solvent accessible. Loss of RprY increased the level of heterotypic community development withStreptococcus gordonii, and the community ‐suppressive function of RprY required Y41. Expression of the Mfa1 fimbrial adhesin was increased in therprY mutant and in the mutant complemented withrprY containing a Y41F mutation. In a microscale thermophoresis assay, recombinant RprY protein bound to t...
Source: Molecular Oral Microbiology - September 15, 2020 Category: Microbiology Authors: Daonan Shen, John D. Perpich, Kendall S. Stocke, Lan Yakoumatos, Zackary R. Fitzsimonds, Chengcheng Liu, Daniel P. Miller, Richard J. Lamont Tags: ORIGINAL ARTICLE Source Type: research

Inflammatory response of uric acid produced by Porphyromonas gingivalis gingipains
In this study, we demonstrate thatP. gingivalis gingipains play a role in THP ‐1 macrophage uric acid production by increasing the expression and activity of xanthine oxidoreductase. Uric acid sodium salt induces caspase‐1 activation, cell death, and the expression of proinflammatory cytokines, including IL‐1α, IL‐6, and IL‐8, in the human keratinocyte HOK‐16B ce ll line. Our results suggest that gingipain‐induced uric acid can mediate inflammation in periodontal tissue cells. (Source: Molecular Oral Microbiology)
Source: Molecular Oral Microbiology - August 13, 2020 Category: Microbiology Authors: Hye ‐Kyung Jun, Sun‐Jin An, Hyun Young Kim, Bong‐Kyu Choi Tags: ORIGINAL ARTICLE Source Type: research

Deletion of csn2 gene affects acid tolerance and exopolysaccharide synthesis in Streptococcus mutans
In this study, we investigated whethercsn2 deletion would affectS. mutans physiology and virulence gene expression. We used microscopic imaging, acid killing assays, pH drop, biofilm formation and exopolysaccharide (EPS) prodction tests to determine whethercsn2 deletion influencedS. mutans colony morphology, acid tolerance/production and glucan formation abilities. Comparisons were made between qRT ‐PCR data from the UA159 andcsn2 deletion strain to determine the impact ofcsn2 knockout onS. mutans gene expression. The results showed that deletion ofS. mutans csn2 changed its colony morphotype and made it more sensitive t...
Source: Molecular Oral Microbiology - August 13, 2020 Category: Microbiology Authors: Anqi Zhang, Jiamin Chen, Tao Gong, Miao Lu, Boyu Tang, Xuedong Zhou, Yuqing Li Tags: ORIGINAL ARTICLE Source Type: research

Filifactor alocis ‐derived extracellular vesicles inhibit osteogenesis through TLR2 signaling
AbstractFilifactor alocis, an asaccharolytic anaerobic Gram ‐positive rod (AAGPR), is an emerging marker of periodontitis. Severe periodontitis causes destruction of the alveolar bone that supports teeth and can even lead to tooth loss. Based on our previous report thatF. alocis‐derived extracellular vesicles (FA EVs) contain various effector molecules and have immunostimulatory activity, we investigated the effect of FA EVs on osteogenesis using mouse bone‐derived mesenchymal stromal cells (BMSCs). FA EVs dramatically inhibited bone mineralization similarly to whole b acteria and reduced the expression levels of ost...
Source: Molecular Oral Microbiology - July 22, 2020 Category: Microbiology Authors: Min ‐Kyoung Song, Hyun Young Kim, Bong‐Kyu Choi, Hong‐Hee Kim Tags: ORIGINAL ARTICLE Source Type: research

Issue Information
Molecular Oral Microbiology, Volume 35, Issue 4, Page i-iii, August 2020. (Source: Molecular Oral Microbiology)
Source: Molecular Oral Microbiology - July 19, 2020 Category: Microbiology Tags: ISSUE INFORMATION Source Type: research

In vivo and ex vivo actions of a novel P. gingivalis inhibitor on multi ‐species biofilm, inflammatory response and periodontal bone loss
SummaryChronic periodontitis is one of the most common infectious inflammatory diseases worldwide. Current therapeutic options for the disease are only partially and temporarily successful due to periodontal re ‐emergence of pathogens such asPorphyromonas gingivalis, a keystone bacterium in the oral microbial communities, which elicits a dysbiosis between the microbiota and the host. Previously, we reported a peptide inhibitor ofP. gingivalis (SAPP) that specifically targetsP. gingivalis and reduces its virulence potentialin vitro. Here, we show that SAPP can modulate the ability ofP. gingivalis to suppress the host inna...
Source: Molecular Oral Microbiology - June 29, 2020 Category: Microbiology Authors: Meng ‐Hsuan Ho, Hatice Hasturk, Daphne F. Young, Hua Xie Tags: ORIGINAL ARTICLE Source Type: research

Sequence and characterization of shuttle vectors for molecular cloning in Porphyromonas, Bacteroides, and related bacteria
AbstractThere is a lack of shuttle vectors to be needed for investigations into the genetics ofPorphyromonas gingivalis and related species. To better understand the prevalence of candidates for such tools we have examined multiple strains of black pigmented anaerobes (clinical and laboratory isolates) for plasmids. As no plasmids were found inP. gingivalis strains, we have used the pYH420 plasmid, derived fromP. asaccharolytica, as backbone to construct a shuttle vector in combination with pUC19 fromEscherichia coli. Nucleotide sequence determination of the pYH420 plasmid revealed that that it contained a gene with simila...
Source: Molecular Oral Microbiology - June 25, 2020 Category: Microbiology Authors: Kevin R. Jones, B. Ross Belvin, Francis L. Macrina, Janina P. Lewis Tags: ORIGINAL ARTICLE Source Type: research

Proteomic analysis of Fusobacterium nucleatum growth in biofilm versus planktonic state
SummaryFusobacterium nucleatum is isolated from both supra ‐ and sub‐gingival dental biofilms in humans and has been implicated in the aetiology of periodontitis. Also, this bacterium plays an important role in serious infections in other parts of the body. The aim of this investigation was to study the protein differential expression ofF. nucleatum when growing on biofilm, compared to planktonic state, using proteomic analysis by the 2D ‐DIGE™ system. Sixty‐eight proteins were differentially expressed during biofilm growth (1.5‐fold, p
Source: Molecular Oral Microbiology - June 17, 2020 Category: Microbiology Authors: Arancha Llama ‐Palacios, Oksana Potupa, María C. Sánchez, Elena Figuero, David Herrera, Mariano Sanz Tags: ORIGINAL ARTICLE Source Type: research

Effects of Porphyromonas gingivalis and Fusobacterium nucleatum on inflammasomes and their regulators in H400 cells
ConclusionPg alone increased IL ‐1β by upregulating AIM2, NLRP3 and downregulating POP1.Fn promoted IL ‐1β by increasing AIM2 and downregulating POP1.Pg+ATP with or withoutFn upregulated NLRP3, IL ‐1β by downregulating POP1. Periodontal pathogens may contribute to HNSCC pathogenesis by increasing the IL‐1β response due to inflammasome dysregulation. (Source: Molecular Oral Microbiology)
Source: Molecular Oral Microbiology - June 8, 2020 Category: Microbiology Authors: K übra Aral, Michael R Milward, Dhanak Gupta, Paul R Cooper Tags: ORIGINAL ARTICLE Source Type: research

Aggregatibacter actinomycetemcomitans leukotoxin: From mechanism to targeted anti ‐toxin therapeutics
Aggregatibacter actinomycetemcomitans is a Gram ‐negative bacterium associated with localized aggressive periodontitis, as well as other systemic diseases. Several studies have demonstrated that clinical isolates from diseased patients frequently belong to specific clones ofA. actinomycetemcomitans that produce significantly higher amounts of leukotoxin (LtxA) suggesting that LtxA might play a key role in pathogenicity. In this article, we review the mechanisms by which LtxA interacts with and kills host cells, highlight the remaining open questions, and demonstrate how knowledge of these mechanisms, enable the design of...
Source: Molecular Oral Microbiology - May 4, 2020 Category: Microbiology Authors: Eric Krueger, Angela C. Brown Tags: REVIEW ARTICLE Source Type: research

Issue Information
Molecular Oral Microbiology, Volume 35, Issue 3, Page i-iv, June 2020. (Source: Molecular Oral Microbiology)
Source: Molecular Oral Microbiology - May 4, 2020 Category: Microbiology Tags: ISSUE INFORMATION Source Type: research

Streptococcus mutans SpxA2 relays the signal of cell envelope stress from LiaR to effectors that maintain cell wall and membrane homeostasis
In this study, the role of thespxA2 transcriptional regulator in these two pathways, and overall cell envelope homeostasis, was examined. Loss ofspxA2 resulted in an increase in the proportion of saturated fatty acids in theS. mutans membrane and altered transcription of several genes involved in the production of these membrane fatty acids, includingfabT andfabM. Furthermore, activity of the F1F0‐ATPase was increased in the ∆spxA2 strain. Transcription ofspxA2 was elevated in the presence of a variety of membrane stressors, and highly dependent on theliaR component of the LiaFSR system, which is known to sense cell en...
Source: Molecular Oral Microbiology - May 4, 2020 Category: Microbiology Authors: Jonathon L. Baker, Sarah Saputo, Roberta C. Faustoferri, Robert G. Quivey Tags: ORIGINAL ARTICLE Source Type: research

The S. mutans mntE gene encodes a manganese efflux transporter
In conclusion, theS. mutans SMU_1176 gene, which we renamedmntE, is a manganese efflux transporter that contributes to essential metal ion homeostasis as part of the SloR regulon. (Source: Molecular Oral Microbiology)
Source: Molecular Oral Microbiology - May 4, 2020 Category: Microbiology Authors: Joseph O'Brien, Alexander Pastora, Andrew Stoner, Grace Spatafora Tags: ORIGINAL ARTICLE Source Type: research

Ribosomal protein L4 of Lactobacillus rhamnosus LRB alters resistance to macrolides and other antibiotics
In this study, we isolated a nontargeted mutant that was particularly sensitive to acid stress. Using next generation sequencing, we further mapped the putative mutations in the genome and found that the mutant had acquired a deletion of 75 base pairs in therplD gene that encodes the large ribosomal subunit L4. The mutant had a growth defect at 37 °C and at ambient temperature. Further antibiotic sensitivity analyses indicated that the mutant is relatively more resistant to erythromycin and chloramphenicol; two antibiotics that target the 50S subunit. In contrast, the mutant was more sensitive to tetracycline, which ta...
Source: Molecular Oral Microbiology - May 4, 2020 Category: Microbiology Authors: Saswati Biswas, Andrew Keightley, Indranil Biswas Tags: ORIGINAL ARTICLE Source Type: research

Issue Information
Molecular Oral Microbiology, Volume 35, Issue 3, Page i-iv, June 2020. (Source: Molecular Oral Microbiology)
Source: Molecular Oral Microbiology - May 4, 2020 Category: Microbiology Tags: ISSUE INFORMATION Source Type: research

Saliva is a non ‐negligible factor in the spread of COVID‐19
SummarySARS ‐CoV‐2, a novel emerging coronavirus, has caused severe disease (COVID‐19), and rapidly spread worldwide since the beginning of 2020. SARS‐CoV‐2 mainly spreads by coughing, sneezing, droplet inhalation, and contact. SARS‐CoV‐2 has been detected in saliva samples, making saliva a potent ial transmission route for COVID‐19. The participants in dental practice confront a particular risk of SARS‐CoV‐2 infection due to close contact with the patients and potential exposure to saliva‐contaminated droplets and aerosols generated during dental procedures. In addition, saliva‐con taminated surfac...
Source: Molecular Oral Microbiology - May 3, 2020 Category: Microbiology Authors: Yuqing Li, Biao Ren, Xian Peng, Tao Hu, Jiyao Li, Tao Gong, Boyu Tang, Xin Xu, Xuedong Zhou Tags: ORIGINAL ARTICLE Source Type: research

Lipoteichoic acid of Enterococcus faecalis interferes with Porphyromonas gingivalis lipopolysaccharide signaling via IRAK ‐M upregulation in human periodontal ligament cells
AbstractPeriodontitis is a chronic inflammatory disease of the gums caused by infection with multispecies oral bacteria. Since the periodontopathic bacteriaPorphyromonas gingivalis together withEnterococcus faecalis are frequently detected in patients with a severe form of periodontitis, interactions between their virulence factors might play an important role in progression of the disease.P. gingivalis andE. faecalis possess lipopolysaccharide (Pg.LPS) and lipoteichoic acid (Ef.LTA), respectively, as the major virulence factors inducing inflammatory responses. However, the combinatorial effect of these virulence factors o...
Source: Molecular Oral Microbiology - April 19, 2020 Category: Microbiology Authors: Jintaek Im, Jung Eun Baik, Dongwook Lee, Kee ‐Yeon Kum, Cheol‐Heui Yun, Ok‐Jin Park, Seung Hyun Han Tags: ORIGINAL ARTICLE Source Type: research

Issue Information
Molecular Oral Microbiology, Volume 35, Issue 2, Page i-iii, April 2020. (Source: Molecular Oral Microbiology)
Source: Molecular Oral Microbiology - March 7, 2020 Category: Microbiology Tags: ISSUE INFORMATION Source Type: research

The S. mutans mntE gene encodes a manganese efflux transporter
In conclusion, theS. mutans SMU_1176 gene, which we renamedmntE, is a manganese efflux transporter that contributes to essential metal ion homeostasis as part of the SloR regulon. (Source: Molecular Oral Microbiology)
Source: Molecular Oral Microbiology - March 4, 2020 Category: Microbiology Authors: Joseph O ’Brien, Alexander Pastora, Andrew Stoner, Grace Spatafora Tags: ORIGINAL ARTICLE Source Type: research

Aggregatibacter actinomycetemcomitans leukotoxin: From mechanism to targeted anti ‐toxin therapeutics
AbstractAggregatibacter actinomycetemcomitans is a Gram ‐negative bacterium associated with localized aggressive periodontitis, as well as other systemic diseases. This organism produces a number of virulence factors, all of which provide some advantage to the bacterium. Several studies have demonstrated that clinical isolates from diseased patients, p articularly those of African descent, frequently belong to specific clones ofA. actinomycetemcomitans that produce significantly higher amounts of a protein exotoxin belonging to the repeats ‐in‐toxin (RTX) family, leukotoxin (LtxA), while isolates from healthy patient...
Source: Molecular Oral Microbiology - February 15, 2020 Category: Microbiology Authors: Eric Krueger, Angela C. Brown Tags: REVIEW ARTICLE Source Type: research

CRISPR ‐Cas systems in oral microbiome: From immune defense to physiological regulation
CRISPR ‐Cas system, found in bacteria and archaea, provides sequence‐based adaptive immunity against mobile genetic elements, including phages and plasmids. The oral cavity contains approximately 700 prokaryote species harboring known CRISPR‐Cas systems. Here, we review the canonical and novel functi ons of the CRISPR‐Cas systems in oral microbiome, including defense against foreign mobile elements, biofilm formation, acquisition of resistance genes, DNA repair, regulation of interspecific competition and intraspecific diversification, stress responses, and gene expression regulation. AbstractThe clustered regularl...
Source: Molecular Oral Microbiology - February 14, 2020 Category: Microbiology Authors: Tao Gong, Jumei Zeng, Boyu Tang, Xuedong Zhou, Yuqing Li Tags: REVIEW ARTICLE Source Type: research

Streptococcus mutans SpxA2 relays the signal of cell envelope stress from LiaR to effectors that maintain cell wall and membrane homeostasis
In this study, the role of thespxA2 transcriptional regulator in these two pathways, and overall cell envelope homeostasis, was examined. Loss ofspxA2 resulted in an increase in the proportion of saturated fatty acids in theS. mutans membrane and altered transcription of several genes involved in the production of these membrane fatty acids, includingfabT andfabM. Furthermore, activity of the F1F0‐ATPase was increased in the ∆spxA2 strain. Transcription ofspxA2 was elevated in the presence of a variety of membrane stressors, and highly dependent on theliaR component of the LiaFSR system, which is known to sense cell en...
Source: Molecular Oral Microbiology - February 11, 2020 Category: Microbiology Authors: Jonathon L. Baker, Sarah Saputo, Roberta C. Faustoferri, Robert G. Quivey Tags: ORIGINAL ARTICLE Source Type: research

Quantitative proteomic analysis of the type IX secretion system mutants in Porphyromonas gingivalis
AbstractPorphyromonas gingivalis is an anaerobic, Gram ‐negative human oral pathogen highly associated with chronic periodontitis.P. gingivalis utilises the type IX secretion system (T9SS) to transport many of its virulence factors including the gingipains to the cell surface. The T9SS is comprised of at least 16 proteins and the involvement of these 16 proteins in the T9SS has been verified by creating gene deletion mutants inP. gingivalis. These T9SS mutants are regularly utilised to understand how these proteins function together to allow the secretion of the T9SS substrates. We performed label ‐free quantitative pr...
Source: Molecular Oral Microbiology - February 11, 2020 Category: Microbiology Authors: Dhana G. Gorasia, Michelle D. Glew, Paul D. Veith, Eric C. Reynolds Tags: ORIGINAL ARTICLE Source Type: research

Ribosomal Protein L4 of Lactobacillus rhamnosus LRB alters resistance to macrolides and other antibiotics
In this study, we isolated a nontargeted mutant that was particularly sensitive to acid stress. Using next generation sequencing, we further mapped the putative mutations in the genome and found that the mutant had acquired a deletion of 75 base pairs in therplD gene that encodes the large ribosomal subunit L4. The mutant had a growth defect at 37 °C and at ambient temperature. Further antibiotic sensitivity analyses indicated that the mutant is relatively more resistant to erythromycin and chloramphenicol; two antibiotics that target the 50S subunit. In contrast, the mutant was more sensitive to tetracycline, which ta...
Source: Molecular Oral Microbiology - February 5, 2020 Category: Microbiology Authors: Saswati Biswas, Andrew Keightley, Indranil Biswas Tags: ORIGINAL ARTICLE Source Type: research

CRISPR ‐Cas system in oral microbiome: from immune defense to physiological regulation
AbstractThe clustered regularly interspaced short palindromic repeats with CRISPR ‐associated proteins (CRISPR‐Cas) system, found in bacteria and archaea, provides sequence‐based adaptive immunity against mobile genetic elements, including phages and plasmids. The oral cavity contains approximately 700 prokaryote species harboring known CRISPR‐Cas systems, including type I, type II, type III, type V, and type VI, and unidentified CRISPR‐Cas systems. There is increasing evidence to suggest that different CRISPR‐Cas systems in the human oral microbiome can affect bacterial physiology through different mechanisms....
Source: Molecular Oral Microbiology - January 28, 2020 Category: Microbiology Authors: Tao Gong, Jumei Zeng, Boyu Tang, Xuedong Zhou, Yuqing Li Tags: REVIEW ARTICLE Source Type: research

Identification of functional domains of the minor fimbrial antigen involved in the interaction of Porphyromonas gingivalis with oral streptococci
AbstractPorphyromonas gingivalis is associated with chronic periodontitis and may initially colonize the oral cavity by adhering to streptococci. Adhesion to streptococci is driven by interaction of the minor fimbrial antigen (Mfa1) with streptococcal antigen I/II. We identified the region of antigen I/II required for this interaction and developed small molecule mimetics that inhibitedP. gingivalis adherence. However, the functional motifs of Mfa1 involved in the interaction with antigen I/II remain uncharacterized. A series of N ‐ and C‐terminal peptide fragments of Mfa1 were expressed and tested for inhibition ofP. ...
Source: Molecular Oral Microbiology - January 27, 2020 Category: Microbiology Authors: Mohammad Roky, John O. Trent, Donald R. Demuth Tags: ORIGINAL ARTICLE Source Type: research

Heterogeneity of Streptococcus anginosus ß‐hemolysis in relation to CRISPR/Cas
AbstractStreptococcus anginosus is a commensal of the oral mucosa that can cause severe invasive infections. A considerable proportion ofStreptococcus anginosus strains are ß‐hemolytic due to the presence of an SLS‐like gene cluster. However, the majority of strains do not display ß‐hemolysis. To investigate ß‐hemolysin heterogeneity inS. anginosus, we determined the presence ofsag genes and correlated it with the presence of CRISPR/Cas genes in a collection of ß‐hemolytic and non‐ß‐hemolytic strains. All of the ß‐hemolytic strains carried thesag gene cluster. In contrast...
Source: Molecular Oral Microbiology - January 23, 2020 Category: Microbiology Authors: Richard Bauer, Nathalie Neffgen, Aline Grempels, Martina Furitsch, Stefanie Mauerer, Salome Barbaqadze, Gerhard Haase, Hans Kestler, Barbara Spellerberg Tags: ORIGINAL ARTICLE Source Type: research