scholarly journals Characterization of Type 2 Quorum Sensing in Klebsiella pneumoniae and Relationship with Biofilm Formation

2005 ◽  
Vol 187 (8) ◽  
pp. 2870-2880 ◽  
Author(s):  
Damien Balestrino ◽  
Janus A. J. Haagensen ◽  
Chantal Rich ◽  
Christiane Forestier
Keyword(s):  
Quorum Sensing ◽  
Klebsiella Pneumoniae ◽  
Biofilm Formation ◽  
Bacterial Species ◽  
Microscopic Analysis ◽  
Opportunistic Pathogen ◽  
Signaling Molecules ◽  
Pcr Analysis

ABSTRACT Quorum sensing is a process by which bacteria communicate by using secreted chemical signaling molecules called autoinducers. Many bacterial species modulate the expression of a wide variety of physiological functions in response to changes in population density by this mechanism. In this study, the opportunistic pathogen Klebsiella pneumoniae was observed to secrete type 2 signaling molecules. A homologue of luxS, the gene required for AI-2 synthesis in Vibrio harveyi, was isolated from the K. pneumoniae genome. A V. harveyi bioassay showed the luxS functionality in K. pneumoniae and its ability to complement the luxS-negative phenotype of Escherichia coli DH5α. Autoinducer activity was detected in the supernatant, and maximum expression of specific messengers detected by quantitative reverse transcription-PCR analysis occurred during the late exponential phase. The highest levels of AI-2 were observed in minimal medium supplemented with glycerol. To determine the potential role of luxS in colonization processes, a K. pneumoniae luxS isogenic mutant was constructed and tested for its capacity to form biofilms in vitro on an abiotic surface and to colonize the intestinal tract in a murine model. No difference was observed in the level of intestinal colonization between the wild-type strain and the luxS mutant. Microscopic analysis of biofilm structures revealed that the luxS mutant was able to form a mature biofilm but with reduced capacities in the development of microcolonies, mostly in the early steps of biofilm formation. These data suggest that a LuxS-dependent signal plays a role in the early stages of biofilm formation by K. pneumoniae.

scholarly journals Mutation of luxS Affects Biofilm Formation in Streptococcus mutans

2003 ◽  
Vol 71 (4) ◽  
pp. 1972-1979 ◽  
Author(s):  
Justin Merritt ◽  
Fengxia Qi ◽  
Steven D. Goodman ◽  
Maxwell H. Anderson ◽  
Wenyuan Shi
Keyword(s):  
Quorum Sensing ◽  
Streptococcus Mutans ◽  
Biofilm Formation ◽  
Microscopic Analysis ◽  
Homoserine Lactone ◽  
Good Evidence ◽  
Genome Project ◽  
Bacterial Biofilm ◽  
Wild Type

ABSTRACT Quorum sensing is a bacterial mechanism for regulating gene expression in response to changes in population density. Many bacteria are capable of acyl-homoserine lactone-based or peptide-based intraspecies quorum sensing and luxS-dependent interspecies quorum sensing. While there is good evidence about the involvement of intraspecies quorum sensing in bacterial biofilm, little is known about the role of luxS in biofilm formation. In this study, we report for the first time that luxS-dependent quorum sensing is involved in biofilm formation of Streptococcus mutans. S. mutans is a major cariogenic bacterium in the multispecies bacterial biofilm commonly known as dental plaque. An ortholog of luxS for S. mutans was identified using the data available in the S. mutans genome project (http://www.genome.ou.edu/smutans.html ). Using an assay developed for the detection of the LuxS-associated quorum sensing signal autoinducer 2 (AI-2), it was demonstrated that this ortholog was able to complement the luxS negative phenotype of Escherichia coli DH5α. It was also shown that AI-2 is indeed produced by S. mutans. AI-2 production is maximal during mid- to late-log growth in batch culture. Mutant strains devoid of the luxS gene were constructed and found to be defective in producing the AI-2 signal. There are also marked phenotypic differences between the wild type and the luxS mutants. Microscopic analysis of in vitro-grown biofilm structure revealed that the luxS mutant biofilms adopted a much more granular appearance, rather than the relatively smooth, confluent layer normally seen in the wild type. These results suggest that LuxS-dependent signal may play an important role in biofilm formation of S. mutans.

scholarly journals Specific quorum sensing molecules are possibly associated with responses to herbicide toxicity in a Pseudomonas strain

2020 ◽  
Author(s):  
Paloma Nathane Nunes de Freitas ◽  
Amanda Flávia da Silva Rovida ◽  
Caroline Rosa Silva ◽  
Sônia Alvim Veiga Pileggi ◽  
Luiz Ricardo Olchanheski ◽  
...  
Keyword(s):  
Quorum Sensing ◽  
Agricultural Production ◽  
Biofilm Formation ◽  
Structural Changes ◽  
Bacterial Species ◽  
Signaling Molecules ◽  
Oxygen Species ◽  
Physiological Plasticity ◽  
Response System ◽  
Generating System

AbstractPesticides contribute to pest control and increased agricultural production; however, they are toxic to non-target organisms and they contaminate the environment. The exposure of bacteria to these substances can lead to the need for physiological and structural changes for survival, which can be determined by genes whose expression is regulated by quorum sensing (QS). However, it is not yet clear whether these processes can be induced by herbicides. Thus, the aim of this work was to determine whether there is a QS response system in a Pseudomonas fluorescens strain that is modulated by herbicides. This strain was isolated from water storage tanks used for washing pesticide packaging and was tested against herbicides containing saflufenacil, glyphosate, sulfentrazone, 2,4-D, and dicamba as active molecules. We found that this strain possibly uses QS signaling molecules to control the production of reactive oxygen species, whether those produced by the bacterium’s energy generating system or by molecules induced by the presence of saflufenacil and glyphosate. This strain used other signaling molecules for various stages of biofilm formation in the presence of herbicides containing sulfentrazone, 2,4-D, and dicamba. These findings, as an initial screening which will guide new studies, suggest that this strain has a flexibility in gene expression that allows survival in the presence of several stress-inducing molecules, regardless of previous exposure. This represents a model of metabolic and physiological plasticity. Biofilms made up of several bacterial species can use this model in agricultural environments, increasing the potential for degradation of xenobiotics, but with impacts on diversity and functionality of microbiotas in these environments.

scholarly journals Pseudomonas aeruginosa Increases Formation of Multidrug-Tolerant Persister Cells in Response to Quorum-Sensing Signaling Molecules

2010 ◽  
Vol 192 (7) ◽  
pp. 1946-1955 ◽  
Author(s):  
Nina Möker ◽  
Charles R. Dean ◽  
Jianshi Tao
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Quorum Sensing ◽  
Bacterial Species ◽  
Opportunistic Pathogen ◽  
Homoserine Lactone ◽  
Signaling Molecules ◽  
Persister Cells ◽  
E Coli ◽  
Underlying Mechanisms ◽  
Lethal Doses

ABSTRACT Bacterial persister cells constitute a small portion of a culture which is tolerant to killing by lethal doses of bactericidal antibiotics. These phenotypic variants are formed in numerous bacterial species, including those with clinical relevance like the opportunistic pathogen Pseudomonas aeruginosa. Although persisters are believed to contribute to difficulties in the treatment of many infectious diseases, the underlying mechanisms affecting persister formation are not well understood. Here we show that even though P. aeruginosa cultures have a significantly smaller fraction of multidrug-tolerant persister cells than cultures of Escherichia coli or Staphylococcus aureus, they can increase persister numbers in response to quorum-sensing-related signaling molecules. The phenazine pyocyanin (and the closely related molecule paraquat) and the acyl-homoserine lactone 3-OC12-HSL significantly increased the persister numbers in logarithmic P. aeruginosa PAO1 or PA14 cultures but not in E. coli or S. aureus cultures.

Functional Diversity of Quorum Sensing Receptors in Pathogenic Bacteria: Interspecies, Intraspecies and Interkingdom Level

2019 ◽  
Vol 20 (6) ◽  
pp. 655-667 ◽  
Author(s):  
Fazlurrahman Khan ◽  
Aqib Javaid ◽  
Young-Mog Kim
Keyword(s):  
Quorum Sensing ◽  
Biofilm Formation ◽  
Pathogenic Bacteria ◽  
Bacterial Species ◽  
Behavioral Responses ◽  
Past Research ◽  
Signaling Molecules ◽  
Bacterial Virulence ◽  
Resistance Development ◽  
Inhibitory Molecules

The formation of biofilm by pathogenic bacteria is considered as one of the most powerful mechanisms/modes of resistance against the action of several antibiotics. Biofilm is formed as a structural adherent over the surfaces of host, food and equipments etc. and is further functionally coordinated by certain chemicals produced itself. These chemicals are known as quorum sensing (QS) signaling molecules and are involved in the cross talk at interspecies, intraspecies and interkingdom levels thus resulting in the production of virulence factors leading to pathogenesis. Bacteria possess receptors to sense these chemicals, which interact with the incoming QS molecules. It is followed by the secretion of virulence molecules, regulation of bioluminescence, biofilm formation, antibiotic resistance development and motility behavioral responses. In the natural environment, different bacterial species (Gram-positive and Gram-negative) produce QS signaling molecules that are structurally and functionally different. Recent and past research shows that various antagonistic molecules (naturally and chemically synthesized) are characterized to inhibit the formation of biofilm and attenuation of bacterial virulence by blocking the QS receptors. This review article describes about the diverse QS receptors at their structural, functional and production levels. Thus, by blocking these receptors with inhibitory molecules can be a potential therapeutic approach to control pathogenesis. Furthermore, these receptors can also be used as a structural platform to screen the most potent inhibitors with the help of bioinformatics approaches.

scholarly journals Role of MrkJ, a Phosphodiesterase, in Type 3 Fimbrial Expression and Biofilm Formation in Klebsiella pneumoniae

2010 ◽  
Vol 192 (15) ◽  
pp. 3944-3950 ◽  
Author(s):  
Jeremiah G. Johnson ◽  
Steven Clegg
Keyword(s):  
Klebsiella Pneumoniae ◽  
Biofilm Formation ◽  
Opportunistic Pathogen ◽  
Surface Expression ◽  
Reverse Transcription Pcr ◽  
Genes Encoding ◽  
Bacterial Genes ◽  
Type 3

ABSTRACT Klebsiella pneumoniae is an opportunistic pathogen that has been shown to adhere to human extracellular matrices using the type 3 fimbriae. Introduction of plasmids carrying genes known to alter intracellular cyclic-di-GMP pools in Vibrio parahaemolyticus revealed that these genes also altered type 3 fimbrial surface expression in K. pneumoniae. Immediately adjacent to the type 3 fimbrial gene cluster is a gene, mrkJ, that is related to a family of bacterial genes encoding phosphodiesterases. We identify here a role for MrkJ, a functional phosphodiesterase exhibiting homology to EAL domain-containing proteins, in controlling type 3 fimbria production and biofilm formation in K. pneumoniae. Deletion of mrkJ resulted in an increase in type 3 fimbria production and biofilm formation as a result of the accumulation of intracellular cyclic-di-GMP. This gene was shown to encode a functional phosphodiesterase via restoration of motility in a V. parahaemolyticus strain previously shown to accumulate cyclic-di-GMP and in vitro using phosphodiesterase activity assays. The effect of the mrkJ mutation on type 3 fimbrial expression was shown to be at the level of mrkA gene transcription by using quantitative reverse transcription-PCR. These results reveal a previously unknown role for cyclic-di-GMP in type 3 fimbrial production.

scholarly journals In Vitro Evaluation of the Effect of Oral Probiotic Weissella cibaria on the Formation of Multi-Species Oral Biofilms on Dental Implant Surfaces

2021 ◽  
Vol 9 (12) ◽  
pp. 2482
Author(s):  
Mi-Sun Kang ◽  
Geun-Yeong Park
Keyword(s):  
Biofilm Formation ◽  
Quantitative Polymerase Chain Reaction ◽  
Bacterial Species ◽  
Microscopic Analysis ◽  
Fusobacterium Nucleatum ◽  
Titanium Implant ◽  
Culture Methods ◽  
Weissella Cibaria ◽  
Actinomyces Naeslundii

Oral probiotics are beneficial bacteria that can help prevent periodontal disease. However, little is known about the effects of oral probiotics on the formation of implant biofilms. This study aimed to evaluate the effects of oral probiotics Weissella cibaria CMU and CMS1 in an in vitro complex biofilm model on titanium implant surfaces. First, it was identified through colony biofilm assay that W. cibaria CMU and CMS1 inhibit the formation of multi-species biofilms formed by eight types of bacteria. Two types of saliva-coated titanium discs inoculated with early (Streptococcus gordonii, Streptococcus oralis, Streptococcus sanguinis, Actinomyces naeslundii, and Veillonella parvula), secondary (Fusobacterium nucleatum and Prevotella intermedia), and late (Porphyromonas gingivalis) colonizers were treated with the oral probiotics and then incubated anaerobically for three days. The effects of oral probiotics on titanium disc biofilm formation were analyzed using culture methods, quantitative polymerase chain reaction (qPCR), and microscopic analysis. Both probiotics significantly inhibited the formation of biofilm, and all eight bacterial species were significantly reduced. The effectiveness of both probiotic strains was confirmed by all the methods used. Oral probiotics may have dramatically reduced the biofilm formation of secondary colonizers that act as bridges, thus inhibiting biofilm formation on the titanium surface. Our results suggest that the probiotic W. cibaria offers new possibilities for the prevention of peri-implant mucositis.

scholarly journals Induction of Biofilm Formation in Klebsiella pneumoniae ATCC 13884 by Several Drugs: The Possible Role of Quorum Sensing Modulation

Antibiotics ◽  
2018 ◽  
Vol 7 (4) ◽  
pp. 103 ◽  
Author(s):  
Elizabeth Cadavid ◽  
Sara Robledo ◽  
Wiston Quiñones ◽  
Fernando Echeverri
Keyword(s):  
Quorum Sensing ◽  
Klebsiella Pneumoniae ◽  
Biofilm Formation ◽  
Bacterial Resistance ◽  
Homoserine Lactone ◽  
In Vitro Assays ◽  
Bacterial Populations ◽  
Other Substances ◽  
Microplate Reader

Bacterial resistance is caused by several biochemical factors, the formation of biofilm being one of the main causes. This process is triggered by Quorum Sensing (QS), through the production of endogenous molecules, although other substances such as natural products can also do this. In this work, we aimed to determine whether some drugs are involved in the induction of biofilm formation in Klebsiella pneumoniae ATCC 13884, and thus, increase bacterial resistance. For this, the effect of 22 drugs on K. pneumoniae ATCC 13884 growth was determined at sub-plasmatic concentrations; the production of autoinducer lactones was established by HPLC and with a biosensor. The induction of biofilm formation was determined through crystal violet assay at 585 nm in a microplate reader and using urethral catheters. According to the in vitro assays, some drugs were found to induce biofilm formation in K. pneumoniae ATCC 13884. The effect of acetaminophen, hydrochlorothiazide, and progesterone stood out. The first drug caused several changes in the biochemistry of K. pneumoniae ATCC 13884 related to QS: high synthesis of N-hexanoyl-homoserine lactone, increasing bacterial populations by 27% and biofilm formation by 49%, and a more gentamicin resistant biofilm. Furthermore, it increased the colonization area of urethral catheters. Hydrochlorothiazide showed the biggest increase in the induction of biofilm formation of 51%, and progesterone displayed the greatest ability to provoke bacterial mass adherence but had no effects on K. pneumoniae ATCC 13884 bacterial population growth.

scholarly journals SdiA, a Quorum-Sensing Regulator, Suppresses Fimbriae Expression, Biofilm Formation, and Quorum-Sensing Signaling Molecules Production in Klebsiella pneumoniae

2021 ◽  
Vol 12 ◽  
Author(s):  
Thaisy Pacheco ◽  
Ana Érika Inácio Gomes ◽  
Nathália Maria Gonçalves Siqueira ◽  
Lucas Assoni ◽  
Michelle Darrieux ◽  
...  
Keyword(s):  
Cell Division ◽  
Quorum Sensing ◽  
Klebsiella Pneumoniae ◽  
Mutant Strain ◽  
Virulence Factors ◽  
Biofilm Formation ◽  
Bacterial Species ◽  
Bacterial Cells ◽  
Gram Negative

Klebsiella pneumoniae is a Gram-negative pathogen that has become a worldwide concern due to the emergence of multidrug-resistant isolates responsible for various invasive infectious diseases. Biofilm formation constitutes a major virulence factor for K. pneumoniae and relies on the expression of fimbrial adhesins and aggregation of bacterial cells on biotic or abiotic surfaces in a coordinated manner. During biofilm aggregation, bacterial cells communicate with each other through inter- or intra-species interactions mediated by signallng molecules, called autoinducers, in a mechanism known as quorum sensing (QS). In most Gram-negative bacteria, intra-species communication typically involves the LuxI/LuxR system: LuxI synthase produces N-acyl homoserine lactones (AHLs) as autoinducers and the LuxR transcription factor is their cognate receptor. However, K. pneumoniae does not produce AHL but encodes SdiA, an orphan LuxR-type receptor that responds to exogenous AHL molecules produced by other bacterial species. While SdiA regulates several cellular processes and the expression of virulence factors in many pathogens, the role of this regulator in K. pneumoniae remains unknown. In this study, we describe the characterization of sdiA mutant strain of K. pneumoniae. The sdiA mutant strain has increased biofilm formation, which correlates with the increased expression of type 1 fimbriae, thus revealing a repressive role of SdiA in fimbriae expression and bacterial cell adherence and aggregation. On the other hand, SdiA acts as a transcriptional activator of cell division machinery assembly in the septum, since cells lacking SdiA regulator exhibited a filamentary shape rather than the typical rod shape. We also show that K. pneumoniae cells lacking SdiA regulator present constant production of QS autoinducers at maximum levels, suggesting a putative role for SdiA in the regulation of AI-2 production. Taken together, our results demonstrate that SdiA regulates cell division and the expression of virulence factors such as fimbriae expression, biofilm formation, and production of QS autoinducers in K. pneumoniae.

scholarly journals Attenuation of Pseudomonas aeruginosa Quorum Sensing by Natural Products: Virtual Screening, Evaluation and Biomolecular Interactions

2020 ◽  
Vol 21 (6) ◽  
pp. 2190 ◽  
Author(s):  
Lin Zhong ◽  
Vinothkannan Ravichandran ◽  
Na Zhang ◽  
Hailong Wang ◽  
Xiaoying Bian ◽  
...  
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Natural Products ◽  
Quorum Sensing ◽  
Biofilm Formation ◽  
Bacterial Species ◽  
In Vitro Assays ◽  
Biomolecular Interactions ◽  
Multi Drug Resistance ◽  
In Silico Studies

Natural products play vital roles against infectious diseases since ancient times and most drugs in use today are derived from natural sources. Worldwide, multi-drug resistance becomes a massive threat to the society with increasing mortality. Hence, it is very crucial to identify alternate strategies to control these ‘super bugs’. Pseudomonas aeruginosa is an opportunistic pathogen reported to be resistant to a large number of critically important antibiotics. Quorum sensing (QS) is a cell–cell communication mechanism, regulates the biofilm formation and virulence factors that endow pathogenesis in various bacteria including P. aeruginosa. In this study, we identified and evaluated quorum sensing inhibitors (QSIs) from plant-based natural products against P. aeruginosa. In silico studies revealed that catechin-7-xyloside (C7X), sappanol and butein were capable of interacting with LasR, a LuxR-type quorum sensing regulator of P. aeruginosa. In vitro assays suggested that these QSIs significantly reduced the biofilm formation, pyocyanin, elastase, and rhamnolipid without influencing the growth. Especially, butein reduced the biofilm formation up to 72.45% at 100 µM concentration while C7X and sappanol inhibited the biofilm up to 66% and 54.26% respectively. Microscale thermophoresis analysis revealed that C7X had potential interaction with LasR (KD = 933±369 nM) and thermal shift assay further confirmed the biomolecular interactions. These results suggested that QSIs are able to substantially obstruct the P. aeruginosa QS. Since LuxR-type transcriptional regulator homologues are present in numerous bacterial species, these QSIs may be developed as broad spectrum anti-infectives in the future.

scholarly journals Role of Heat Shock Proteases in Quorum-Sensing-Mediated Regulation of Biofilm Formation by Vibrio Species

mBio ◽  
2018 ◽  
Vol 9 (1) ◽  
Author(s):  
Kyung-Jo Lee ◽  
You-Chul Jung ◽  
Soon-Jung Park ◽  
Kyu-Ho Lee
Keyword(s):  
Heat Shock ◽  
Quorum Sensing ◽  
Cell Density ◽  
Biofilm Formation ◽  
Pathogenic Bacteria ◽  
Capsular Polysaccharide ◽  
Signaling Molecules ◽  
Master Regulators

ABSTRACTCapsular polysaccharide (CPS) is essential for the dispersal of biofilms formed by the pathogenic bacteriumVibrio vulnificus. CPS production is induced by the quorum-sensing (QS) master regulator SmcR when biofilms mature. However,V. vulnificusbiofilms formed under heat shock conditions did not exhibit the dispersion stage. Transcripts of the CPS gene cluster were at basal levels in the heat-exposed cell owing to reduced cellular levels of SmcR. At least two proteases induced by heat shock, ClpPA and Lon, were responsible for determining the instability of SmcR.In vitroandin vivoassays demonstrated that SmcR levels were regulated via proteolysis by these proteases, with preferential proteolysis of monomeric SmcR. Thus, CPS production was not induced by QS when bacteria were heat treated. Further studies performed with otherVibriospecies demonstrated that high temperature deactivated the QS circuits by increased proteolysis of their QS master regulators, thus resulting in alterations to the QS-regulated phenotypes, including biofilm formation.IMPORTANCEThe term "quorum-sensing mechanism" is used to describe diverse bacterial cell density-dependent activities that are achieved by sensing of the signaling molecules and subsequent signal transduction to the master regulators. These well-known bacterial regulatory systems regulate the expression of diverse virulence factors and the construction of biofilms in pathogenic bacteria. There have been numerous studies designed to control bacterial quorum sensing by using small molecules to antagonize the quorum-sensing regulatory components or to interfere with the signaling molecules. In the present study, we showed that the quorum-sensing regulatory circuits of pathogenicVibriospecies were deactivated by heat shock treatment via highly increased proteolysis of the master transcription factors. Our results showed a new mode of quorum deactivation which can be achieved under conditions of high but nonlethal temperature even if the ambient signaling molecules may reach the levels representing high cell density.

Sign in / Sign up

Export Citation Format

Share Document