scholarly journals Transcriptional Regulation of the tad Locus in Aggregatibacter actinomycetemcomitans: a Termination Cascade

2008 ◽  
Vol 190 (11) ◽  
pp. 3859-3868 ◽  
Author(s):  
Karin E. Kram ◽  
Galadriel A. Hovel-Miner ◽  
Mladen Tomich ◽  
David H. Figurski
Keyword(s):  
Bacterial Adhesion ◽  
Biofilm Formation ◽  
Aggregatibacter Actinomycetemcomitans ◽  
Northern Hybridization ◽  
Reporter Plasmid ◽  
Complete Understanding ◽  
Transcriptional Termination ◽  
Pilus Biogenesis ◽  
Pilin Gene ◽  
And Behavior

ABSTRACT The tad (tight adherence) locus of Aggregatibacter actinomycetemcomitans includes genes for the biogenesis of Flp pili, which are necessary for bacterial adhesion to surfaces, biofilm formation, and pathogenesis. Although studies have elucidated the functions of some of the Tad proteins, little is known about the regulation of the tad locus in A. actinomycetemcomitans. A promoter upstream of the tad locus was previously identified and shown to function in Escherichia coli. Using a specially constructed reporter plasmid, we show here that this promoter (tadp) functions in A. actinomycetemcomitans. To study expression of the pilin gene (flp-1) relative to that of tad secretion complex genes, we used Northern hybridization analysis and a lacZ reporter assay. We identified three terminators, two of which (T1 and T2) can explain flp-1 mRNA abundance, while the third (T3) is at the end of the locus. T1 and T3 have the appearance and behavior of intrinsic terminators, while T2 has a different structure and is inhibited by bicyclomycin, indicating that T2 is probably Rho dependent. To help achieve the appropriate stoichiometry of the Tad proteins, we show that a transcriptional-termination cascade is important to the proper expression of the tad genes. These data indicate a previously unreported mechanism of regulation in A. actinomycetemcomitans and lead to a more complete understanding of its Flp pilus biogenesis.

scholarly journals Influence of Aae Autotransporter Protein on Adhesion and Biofilm Formation by Aggregatibacter actinomycetemcomitans

2016 ◽  
Vol 27 (3) ◽  
pp. 255-260 ◽  
Author(s):  
Ana Carla Robatto Nunes ◽  
Priscila Larcher Longo ◽  
Marcia Pinto Alves Mayer
Keyword(s):  
Epithelial Cells ◽  
Bacterial Adhesion ◽  
Parental Strain ◽  
Biofilm Formation ◽  
Aggregatibacter Actinomycetemcomitans ◽  
Salivary Proteins ◽  
Null Mutant ◽  
Hydrophobic Properties ◽  
Multiple Functions

Abstract The periodontopathogen Aggregatibacter actinomycetemcomitans colonizes oral cavity by binding to and invading epithelial cells as well as by participating in biofilms formed on hard surfaces. Aae, an autotransporter protein, is implicated in bacterial adhesion to epithelial cells. Due to the multiple functions of bacterial autotransporter proteins, this study aimed to evaluate the role of aae in A. actinomycetemcomitans ability to adhere to both saliva-coated hydroxyapatite (SHA) and biofilm. An aae null mutant was constructed. Its hydrophobic properties as well as its ability to adhere to epithelial cells, SHA and to form biofilm were evaluated and compared with the parental strain, A. actinomycetemcomitans VT1169. The aae null mutant showed reduced hydrophobicity, as well as decreased binding to SHA and biofilm formation compared to the parental strain. These data suggest that aae mediates A. actinomycetemcomitans adhesion to epithelial cells and may be involved in biofilm formation and interaction with adsorbed salivary proteins.

scholarly journals Bond Strengthening in Oral Bacterial Adhesion to Salivary Conditioning Films

2008 ◽  
Vol 74 (17) ◽  
pp. 5511-5515 ◽  
Author(s):  
Henny C. van der Mei ◽  
Minie Rustema-Abbing ◽  
Joop de Vries ◽  
Henk J. Busscher
Keyword(s):  
Bacterial Adhesion ◽  
Biofilm Formation ◽  
Specific Interactions ◽  
Adhesion Forces ◽  
Bacterial Strains ◽  
Bacterial Interactions ◽  
Initial Adhesion ◽  
Conditioning Film ◽  
Interacting Surfaces ◽  
Conditioning Films

ABSTRACT Transition from reversible to irreversible bacterial adhesion is a highly relevant but poorly understood step in initial biofilm formation. We hypothesize that in oral biofilm formation, irreversible adhesion is caused by bond strengthening due to specific bacterial interactions with salivary conditioning films. Here, we compared the initial adhesion of six oral bacterial strains to salivary conditioning films with their adhesion to a bovine serum albumin (BSA) coating and related their adhesion to the strengthening of the binding forces measured with bacteria-coated atomic force microscopy cantilevers. All strains adhered in higher numbers to salivary conditioning films than to BSA coatings, and specific bacterial interactions with salivary conditioning films were accompanied by stronger initial adhesion forces. Bond strengthening occurred on a time scale of several tens of seconds and was slower for actinomyces than for streptococci. Nonspecific interactions between bacteria and BSA coatings strengthened twofold faster than their specific interactions with salivary conditioning films, likely because specific interactions require a closer approach of interacting surfaces with the removal of interfacial water and a more extensive rearrangement of surface structures. After bond strengthening, bacterial adhesion forces with a salivary conditioning film remained stronger than those with BSA coatings.

scholarly journals A Real-Time Thermal Sensor System for Quantifying the Inhibitory Effect of Antimicrobial Peptides on Bacterial Adhesion and Biofilm Formation

Sensors ◽  
2021 ◽  
Vol 21 (8) ◽  
pp. 2771
Author(s):  
Tobias Wieland ◽  
Julia Assmann ◽  
Astrid Bethe ◽  
Christian Fidelak ◽  
Helena Gmoser ◽  
...  
Keyword(s):  
Antimicrobial Peptides ◽  
Real Time ◽  
Bacterial Adhesion ◽  
Biofilm Formation ◽  
Pathogenic Bacteria ◽  
Bovine Mastitis ◽  
Inhibitory Effect ◽  
Thermal Sensor ◽  
Bacterial Cells ◽  
Static Conditions

The increasing rate of antimicrobial resistance (AMR) in pathogenic bacteria is a global threat to human and veterinary medicine. Beyond antibiotics, antimicrobial peptides (AMPs) might be an alternative to inhibit the growth of bacteria, including AMR pathogens, on different surfaces. Biofilm formation, which starts out as bacterial adhesion, poses additional challenges for antibiotics targeting bacterial cells. The objective of this study was to establish a real-time method for the monitoring of the inhibition of (a) bacterial adhesion to a defined substrate and (b) biofilm formation by AMPs using an innovative thermal sensor. We provide evidence that the thermal sensor enables continuous monitoring of the effect of two potent AMPs, protamine and OH-CATH-30, on surface colonization of bovine mastitis-associated Escherichia (E.) coli and Staphylococcus (S.) aureus. The bacteria were grown under static conditions on the surface of the sensor membrane, on which temperature oscillations generated by a heater structure were detected by an amorphous germanium thermistor. Bacterial adhesion, which was confirmed by white light interferometry, caused a detectable amplitude change and phase shift. To our knowledge, the thermal measurement system has never been used to assess the effect of AMPs on bacterial adhesion in real time before. The system could be used to screen and evaluate bacterial adhesion inhibition of both known and novel AMPs.

Bacterial adhesion to collagens: implications for biofilm formation and disease progression in the oral cavity

2021 ◽  
pp. 1-13
Author(s):  
Simón Álvarez ◽  
Camila Leiva-Sabadini ◽  
Christina M. A. P. Schuh ◽  
Sebastian Aguayo
Keyword(s):  
Oral Cavity ◽  
Disease Progression ◽  
Bacterial Adhesion ◽  
Biofilm Formation

Monolithic Ceramics: Effect of Finishing Techniques on Surface Properties, Bacterial Adhesion and Cell Viability

2018 ◽  
Vol 43 (3) ◽  
pp. 315-325 ◽  
Author(s):  
AMO Dal Piva ◽  
LPC Contreras ◽  
FC Ribeiro ◽  
LC Anami ◽  
SEA Camargo ◽  
...  
Keyword(s):  
Mtt Assay ◽  
Bacterial Adhesion ◽  
Biofilm Formation ◽  
Nonparametric Tests ◽  
Lithium Silicate ◽  
Gingival Fibroblasts ◽  
Sem Images ◽  
High Profile ◽  
Colony Forming Units ◽  
Monolithic Ceramics

SUMMARY Introduction: This study evaluated the morphology, biofilm formation, and viability of human gingival fibroblasts in contact with two monolithic ceramics after two different finishing techniques: polishing or glazing. For this, 92 blocks (4.5 × 4.5 × 1.5 mm) of each ceramic were made using high translucency zirconia partially stabilized by yttrium (YZHT) and lithium silicate reinforced by zirconium (ZLS). Methods and Materials: Blocks were sintered and then divided into glazing (g) or polishing (p) surface finish. Surface roughness (Ra and RSm) was evaluated through a contact rugosimeter and profilometry. Specimens were contaminated for heterotypic biofilm formation with Streptococcus mutans, Streptococcus sanguinis and Candida albicans for 16 hours. Biofilm was quantified by counting the colony forming units (CFU/mL) and analyzed by scanning electron microscopy (SEM). Fibroblast viability was evaluated by MTT assay. Surface free energy (SFE) was also determined. Roughness data were evaluated using nonparametric tests, while SFE, MTT and CFU results were evaluated by analysis of variance and Tukey test, and MTT data were also submitted to t-test (all, α=0.05). Results: Results showed that polished samples presented a lower high profile mean (p<0.001); however, YZHTg presented less space between defects (p=0.0002). SFE showed that YZHT presented higher SFE than ZLS. Profilometry evidenced more homogeneity on polished surfaces. The interaction of finishing technique and microorganisms influenced the CFU (p=0.00). MTT assay demonstrated initial severe cytotoxic behavior for polished surfaces. SEM images showed homogeneous surfaces, except for glazed YZHT. Conclusion: Glazed surfaces have a greater roughness and tend to accumulate more biofilm. Polished surfaces have higher SFE; however, they are temporarily cytotoxic.

scholarly journals Pilus Biogenesis in Lactococcus lactis: Molecular Characterization and Role in Aggregation and Biofilm Formation

PLoS ONE ◽  
2012 ◽  
Vol 7 (12) ◽  
pp. e50989 ◽  
Author(s):  
Virginie Oxaran ◽  
Florence Ledue-Clier ◽  
Yakhya Dieye ◽  
Jean-Marie Herry ◽  
Christine Péchoux ◽  
...  
Keyword(s):  
Molecular Characterization ◽  
Lactococcus Lactis ◽  
Biofilm Formation ◽  
Pilus Biogenesis

scholarly journals Anhydride-functional silane immobilized onto titanium surfaces induces osteoblast cell differentiation and reduces bacterial adhesion and biofilm formation

2016 ◽  
Vol 59 ◽  
pp. 524-532 ◽  
Author(s):  
Maria Godoy-Gallardo ◽  
Jordi Guillem-Marti ◽  
Pablo Sevilla ◽  
José M. Manero ◽  
Francisco J. Gil ◽  
...  
Keyword(s):  
Cell Differentiation ◽  
Bacterial Adhesion ◽  
Biofilm Formation ◽  
Osteoblast Cell ◽  
Titanium Surfaces

scholarly journals Antimicrobial Resistance and Biofilm Formation of Pseudomonas aeruginosa

10.3823/846 ◽  
2020 ◽  
Vol 10 (2) ◽  
Author(s):  
Abdelraouf A Elmanama ◽  
Suhaila Al-Sheboul ◽  
Renad I Abu-Dan
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Antibiotic Resistance ◽  
Antimicrobial Resistance ◽  
Quorum Sensing ◽  
Bacterial Adhesion ◽  
Biofilm Formation ◽  
Bacterial Infections ◽  
Developmental Stages ◽  
Infection Site ◽  
Major Virulence Factor

Abstract Pseudomonas aeruginosa threatens patient’s care. It is considered as the most complicated health care associated pathogen to be eliminated from infection site. The biofilm forming ability of P. aeruginosa, being a major virulence factor for most pathogenic microorganism, protects it from host immunity and contribute to antibiotic resistance of this organism. It is estimated that about 80% of infectious diseases are due to biofilm mode of growth. Biofilm forming ability of bacteria imparts antimicrobial resistance that leads to many persistent and chronic bacterial infections. The world is becoming increasingly under the threat of entering the “post-antibiotic era”, an era in which the rate of death from bacterial infections is higher than from cancer. This review focus on P. aeruginosa biofilm forming ability; definition, developmental stages, and significance. In addition, the quorum sensing and the antibiotic resistance of this pathogen is discussed. Keywords: Biofilm; bacterial adhesion; Pseudomonas aeruginosa; antimicrobial resistance; quorum sensing.

scholarly journals Carbonated Hydroxyapatite Containing Propolis as an Antibacterial Agent Candidate against Aggregatibacter actinomycetemcomitans

2020 ◽  
Vol 25 (3) ◽  
Author(s):  
Ayunda Nur Sukmawati ◽  
Sri Pramestri ◽  
Al. Sri Koes Soesilowati ◽  
Suryono Suryono
Keyword(s):  
Antibacterial Activity ◽  
Bacterial Adhesion ◽  
Antibacterial Agent ◽  
Alveolar Bone ◽  
Inhibition Zone ◽  
Aggregatibacter Actinomycetemcomitans ◽  
Test Method ◽  
Graft Material ◽  
Carbonated Hydroxyapatite ◽  
Significant Difference

One of the periodontal pathogenic bacteria that can cause periodontitis and alveolar bone destruction is Aggregatibacter actinomycetemcomitans. An alveolar bone defect can be treated using a bone graft. Carbonated hydroxyapatite (CHA) is an alloplastic graft material. Alloplastic materials do not have vascularization, which will increase the risk of bacterial adhesion. Therefore, adding an antibacterial agent is needed to prevent bacterial adhesion, which will improve periodontal healing. Propolis is a natural ingredient that has broad-spectrum antibacterial activity and does not cause bacterial resistance. This study aimed to assess the antibacterial activity of carbonated hydroxyapatite after being incorporated with propolis against Aggregatibacter actinomycetemcomitans. Carbonated hydroxyapatite was embedded into four different concentrations of propolis solution (2.5%, 5%, 7.5%, and 10%). An antimicrobial assay against Aggregatibacter actinomycetemcomitans was done using the disc diffusion test method. The inhibition zone was measured to determine the antibacterial ability of the specimens. The inhibition zone was found on the carbonated hydroxyapatite incorporated with propolis at all concentrations. Carbonated hydroxyapatite incorporated with 10% propolis showed the largest inhibition zone. Data analysis using the Kruskal–Wallis test showed a significant difference between the groups tested (p <.05). In conclusion, carbonated hydroxyapatite incorporated with propolis has antibacterial activity against Aggregatibacter actinomycetemcomitans

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