A versatile plasmid biosensor useful to identify quorum sensing LuxR-family orphans in bacterial strains

2008 ◽  
Vol 73 (3) ◽  
pp. 273-275 ◽  
Author(s):  
Laura Steindler ◽  
Giulia Devescovi ◽  
Sujatha Subramoni ◽  
Vittorio Venturi
Keyword(s):  
Quorum Sensing ◽  
Bacterial Strains

scholarly journals Integrated Genomic and Metabolomic Approach to the Discovery of Potential Anti-Quorum Sensing Natural Products from Microbes Associated with Marine Samples from Singapore

Marine Drugs ◽  
2019 ◽  
Vol 17 (1) ◽  
pp. 72 ◽  
Author(s):  
Ji Ong ◽  
Hui Goh ◽  
Swee Lim ◽  
Li Pang ◽  
Joyce Chin ◽  
...  
Keyword(s):  
Drug Discovery ◽  
Quorum Sensing ◽  
Large Scale ◽  
Marine Ecosystem ◽  
Gene Clusters ◽  
Integrated Approach ◽  
Rrna Gene ◽  
Dependent Manner ◽  
Bacterial Strains ◽  
Reporter System

With 70% of the Earth’s surface covered in water, the marine ecosystem offers immense opportunities for drug discovery and development. Due to the decreasing rate of novel natural product discovery from terrestrial sources in recent years, many researchers are beginning to look seaward for breakthroughs in new therapeutic agents. As part of an ongoing marine drug discovery programme in Singapore, an integrated approach of combining metabolomic and genomic techniques were initiated for uncovering novel anti-quorum sensing molecules from bacteria associated with subtidal samples collected in the Singapore Strait. Based on the culture-dependent method, a total of 102 marine bacteria strains were isolated and the identities of selected strains were established based on their 16S rRNA gene sequences. About 5% of the marine bacterial organic extracts showed quorum sensing inhibitory (QSI) activity in a dose-dependent manner based on the Pseudomonas aeruginosa QS reporter system. In addition, the extracts were subjected to mass spectrometry-based molecular networking and the genome of selected strains were analysed for known as well as new biosynthetic gene clusters. This study revealed that using integrated techniques, coupled with biological assays, can provide an effective and rapid prioritization of marine bacterial strains for downstream large-scale culturing for the purpose of isolation and structural elucidation of novel bioactive compounds.

Characterization of two LuxI/R homologs in Pantoea ananatis LMG 2665T

2016 ◽  
Vol 62 (11) ◽  
pp. 893-903 ◽  
Author(s):  
Siphathele Sibanda ◽  
Jacques Theron ◽  
Divine Y. Shyntum ◽  
Lucy N. Moleleki ◽  
Teresa A. Coutinho
Keyword(s):  
Quorum Sensing ◽  
Genome Sequence ◽  
Biofilm Formation ◽  
Biological Significance ◽  
Bacterial Strains ◽  
Pantoea Ananatis ◽  
Ecological Fitness ◽  
Host Interactions

Quorum sensing (QS) plays an important role in the regulation of bacteria–host interactions and ecological fitness in many bacteria. In this study, 2 luxI/R homologs, namely eanI/eanR and rhlI/rhlR, were identified in the genome sequence of Pantoea ananatis LMG 2665T. To determine a role for these luxI/R homologs in pathogenicity and biofilm formation, mutant bacterial strains lacking either eanI/R or rhlI/R and both of these homologs were generated. The results indicated that both the RhlI/R and EanI/R systems are required for pathogenicity and biofilm formation in strain LMG 2665T. This is the first study to characterize the biological significance of the RhlI/R QS system in P. ananatis.

scholarly journals Evolution of the quorum sensing regulon in cooperating populations of Pseudomonas aeruginosa

2021 ◽  
Author(s):  
Nicole E Smalley ◽  
Amy L Schaefer ◽  
Kyle L Asfahl ◽  
Crystal Perez ◽  
E Peter Greenberg ◽  
...  
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Quorum Sensing ◽  
Cell Communication ◽  
Opportunistic Pathogen ◽  
Quorum Quenching ◽  
Homoserine Lactone ◽  
Rna Seq ◽  
Bacterial Strains ◽  
Communication And Coordination

The bacterium Pseudomonas aeruginosa is an opportunistic pathogen and it thrives in many different saprophytic habitats. In this bacterium acyl-homoserine lactone quorum sensing (QS) can activate expression of over 100 genes, many of which code for extracellular products. P. aeruginosa has become a model for studies of cell-cell communication and coordination of cooperative activities. We hypothesized that long-term growth of bacteria under conditions where only limited QS-controlled functions were required would result in a reduction in the size of the QS-controlled regulon. To test this hypothesis, we grew P. aeruginosa for about 1000 generations in a condition in which expression of QS-activated genes is required for growth. We compared the QS regulons of populations after about 35 generations to those after about 1000 generations in two independent lineages by using quorum quenching and RNA-seq technology. In one evolved lineage the number of QS-activated genes identified was reduced by about 70% and in the other by about 45%. Our results lend important insights about the variations in the number of QS-activated genes reported for different bacterial strains and, more broadly, about the environmental histories of P. aeruginosa.

scholarly journals Selection and Characterization of Burkholderia spp. for Their Plant-Growth Promoting Effects and Influence on Maize Seed Germination

2022 ◽  
Vol 1 ◽  
Author(s):  
Isaneli Batista dos Santos ◽  
Arthur Prudêncio de Araújo Pereira ◽  
Adijailton José de Souza ◽  
Elke Jurandy Bran Nogueira Cardoso ◽  
Flaviana Gonçalves da Silva ◽  
...  
Keyword(s):  
Seed Germination ◽  
Quorum Sensing ◽  
Genetic Variability ◽  
Plant Growth ◽  
Bacterial Strains ◽  
Initial Development ◽  
Corn Seed ◽  
Plant Growth Promoting ◽  
Promote Plant Growth ◽  
Growth Promoting

Burkholderia sp. is a bacterial genus extremely versatile in the environment and has been reported for a great potential to promote plant growth via different mechanisms. Here we evaluate the plant growth-promoting mechanisms in twenty-six Burkholderia strains. Strains were evaluated for their ability to promote plant growth by means of: indole-3-acetic acid (IAA) production under different conditions of pH, salt stress and the presence or absence of L-tryptophan; exopolysaccharides (EPS) production and quorum sensing (ALH). The strains were also characterized in terms of their genetic variability and species identification through Sanger sequencing. Then, the bacteria most responsive in the greatest number of plant-growth promotion mechanisms were selected for a corn seed germination test. All bacteria synthesized IAA in medium with 0.0 or 5.0 mM of L-tryptophan in combination with either 1 or 5% of NaCl, and pH values of either 4.5 or 7.2. The EPS production was confirmed for 61.54% of the bacterial strains. Quorum sensing also occurred in 92.3% of the selected bacteria. The Jaccard similarity coefficient revealed 16 clusters with high genetic variability between bacterial strains. Bacterial strains were assigned to seven species: B. anthina, B. cepacia, B. gladioli, B. ambifaria, B. graminis, B. heleia, and Burkholderia spp. The corn seed bacterization did not affect the germination velocity index (GSI), as well as the first count of germinated seeds (FC). However, inoculations formulated with B. heleia strain G28, B. gladioli strain UAGC723, and B. graminis strain UAGC348 promoted significant increases in root length, seedling height and fresh and dry seedling phytomass, respectively. These results indicate the high biotechnological potential of several strains in the genus Burkholderia sp. as seed inoculants, favoring germination and seedling initial development.

scholarly journals l-Canavanine Made by Medicago sativa Interferes with Quorum Sensing in Sinorhizobium meliloti

2005 ◽  
Vol 187 (24) ◽  
pp. 8427-8436 ◽  
Author(s):  
Neela D. Keshavan ◽  
Puneet K. Chowdhary ◽  
Donovan C. Haines ◽  
Juan E. González
Keyword(s):  
Quorum Sensing ◽  
Medicago Sativa ◽  
Sinorhizobium Meliloti ◽  
Signal Molecules ◽  
Bacterial Strains ◽  
Signal Molecule ◽  
Gram Negative ◽  
Bacterial Quorum Sensing ◽  
Bacterial Quorum ◽  
Regulated Gene Expression

ABSTRACT Sinorhizobium meliloti is a gram-negative soil bacterium, capable of establishing a nitrogen-fixing symbiosis with its legume host, alfalfa (Medicago sativa). Quorum sensing plays a crucial role in this symbiosis, where it influences the nodulation process and the synthesis of the symbiotically important exopolysaccharide II (EPS II). S. meliloti has three quorum-sensing systems (Sin, Tra, and Mel) that use N-acyl homoserine lactones as their quorum-sensing signal molecule. Increasing evidence indicates that certain eukaryotic hosts involved in symbiotic or pathogenic relationships with gram-negative bacteria produce quorum-sensing-interfering (QSI) compounds that can cross-communicate with the bacterial quorum-sensing system. Our studies of alfalfa seed exudates suggested the presence of multiple signal molecules capable of interfering with quorum-sensing-regulated gene expression in different bacterial strains. In this work, we choose one of these QSI molecules (SWI) for further characterization. SWI inhibited violacein production, a phenotype that is regulated by quorum sensing in Chromobacterium violaceum. In addition, this signal molecule also inhibits the expression of the S. meliloti exp genes, responsible for the production of EPS II, a quorum-sensing-regulated phenotype. We identified this molecule as l-canavanine, an arginine analog, produced in large quantities by alfalfa and other legumes.

scholarly journals Cyclic Dipeptides Produced by Marine Sponge-Associated Bacteria as Quorum Sensing Signals

2014 ◽  
Vol 9 (2) ◽  
pp. 1934578X1400900
Author(s):  
Gennaro Roberto Abbamondi ◽  
Salvatore De Rosa ◽  
Carmine Iodice ◽  
Giuseppina Tommonaro
Keyword(s):  
Quorum Sensing ◽  
Quorum Quenching ◽  
Marine Sponges ◽  
Bacterial Strains ◽  
Signal Molecule ◽  
Associated Bacteria ◽  
Cyclic Dipeptides ◽  
Sponge Associated Bacteria ◽  
Dysidea Avara ◽  
Quorum Sensing Signals

Four bacterial strains belonging to the genera Vibrio, Pseudoalteromonas and Photobacterium were isolated from the marine sponges Dysidea avara and Geodia cynodium. A Bacillus strain was isolated from Ircinia variabilis. A screening of molecules involved in quorum sensing (QS) was carried out by TLC-overlay and a new “plate T-streak” test. To analyze quorum quenching (QQ), a plate T-streak was performed with Chromobacterium violaceum. Strains of Vibrio isolated from both marine sponges and a strain of Photobacterium isolated from G. cynodium, activated QS bioreporters. A strain of Pseudoalteromonas isolated from D. avara showed QQ activity. Finally, it is reported that cyclic dipeptides isolated from strains of Vibrio sp. and Bacillus sp. (isolated from D. avara and I. variabilis, respectively) were involved in the QS mechanism. The simultaneous presence of bacteria that showed contrasting responses in bioassays for QS signal molecule synthesis in marine sponges could add an interesting dimension to the signalling interactions which may be happening in sponges.

scholarly journals Assessing the Diversity and Biomedical Potential of Microbes Associated With the Neptune’s Cup Sponge, Cliona patera

2021 ◽  
Vol 12 ◽  
Author(s):  
Xin Yi Ho ◽  
Nursheena Parveen Katermeran ◽  
Lindsey Kane Deignan ◽  
Ma Yadanar Phyo ◽  
Ji Fa Marshall Ong ◽  
...  
Keyword(s):  
Quorum Sensing ◽  
Temporal Stability ◽  
Marine Sponges ◽  
Molecular Networks ◽  
Sponge Tissue ◽  
Prokaryotic Community ◽  
Bacterial Strains ◽  
Tissue Samples ◽  
Bacterial Phyla ◽  
Organic Extracts

Marine sponges are known to host a complex microbial consortium that is essential to the health and resilience of these benthic invertebrates. These sponge-associated microbes are also an important source of therapeutic agents. The Neptune’s Cup sponge, Cliona patera, once believed to be extinct, was rediscovered off the southern coast of Singapore in 2011. The chance discovery of this sponge presented an opportunity to characterize the prokaryotic community of C. patera. Sponge tissue samples were collected from the inner cup, outer cup and stem of C. patera for 16S rRNA amplicon sequencing. C. patera hosted 5,222 distinct OTUs, spanning 26 bacterial phyla, and 74 bacterial classes. The bacterial phylum Proteobacteria, particularly classes Gammaproteobacteria and Alphaproteobacteria, dominated the sponge microbiome. Interestingly, the prokaryotic community structure differed significantly between the cup and stem of C. patera, suggesting that within C. patera there are distinct microenvironments. Moreover, the cup of C. patera had lower diversity and evenness as compared to the stem. Quorum sensing inhibitory (QSI) activities of selected sponge-associated marine bacteria were evaluated and their organic extracts profiled using the MS-based molecular networking platform. Of the 110 distinct marine bacterial strains isolated from sponge samples using culture-dependent methods, about 30% showed quorum sensing inhibitory activity. Preliminary identification of selected QSI active bacterial strains revealed that they belong mostly to classes Alphaproteobacteria and Bacilli. Annotation of the MS/MS molecular networkings of these QSI active organic extracts revealed diverse classes of natural products, including aromatic polyketides, siderophores, pyrrolidine derivatives, indole alkaloids, diketopiperazines, and pyrone derivatives. Moreover, potential novel compounds were detected in several strains as revealed by unique molecular families present in the molecular networks. Further research is required to determine the temporal stability of the microbiome of the host sponge, as well as mining of associated bacteria for novel QS inhibitors.

scholarly journals Insecticidal Bacillus thuringiensis Silences Erwinia carotovora Virulence by a New Form of Microbial Antagonism, Signal Interference

2004 ◽  
Vol 70 (2) ◽  
pp. 954-960 ◽  
Author(s):  
Yi-Hu Dong ◽  
Xi-Fen Zhang ◽  
Jin-Ling Xu ◽  
Lian-Hui Zhang
Keyword(s):  
Bacillus Thuringiensis ◽  
Quorum Sensing ◽  
Bacterial Infections ◽  
Antibiotic Production ◽  
Erwinia Carotovora ◽  
Signal Interference ◽  
In Planta ◽  
Bacterial Strains ◽  
Microbial Antagonism ◽  
New Form

ABSTRACT It is commonly known that bacteria may produce antibiotics to interfere with the normal biological functions of their competitors in order to gain competitive advantages. Here we report that Bacillus thuringiensis suppressed the quorum-sensing-dependent virulence of plant pathogen Erwinia carotovora through a new form of microbial antagonism, signal interference. E. carotovora produces and responds to acyl-homoserine lactone (AHL) quorum-sensing signals to regulate antibiotic production and expression of virulence genes, whereas B. thuringiensis strains possess AHL-lactonase, which is a potent AHL-degrading enzyme. B. thuringiensis did not seem to interfere with the normal growth of E. carotovora; rather, it abolished the accumulation of AHL signal when they were cocultured. In planta, B. thuringiensis significantly decreased the incidence of E. carotovora infection and symptom development of potato soft rot caused by the pathogen. The biocontrol efficiency is correlated with the ability of bacterial strains to produce AHL-lactonase. While all the seven AHL-lactonase-producing B. thuringiensis strains provided significant protection against E. carotovora infection, Bacillus fusiformis and Escherichia coli strains that do not process AHL-degradation enzyme showed little effect in biocontrol. Mutation of aiiA, the gene encoding AHL-lactonase in B. thuringiensis, resulted in a substantial decrease in biocontrol efficacy. These results suggest that signal interference mechanisms existing in natural ecosystems could be explored as a new version of antagonism for prevention of bacterial infections.

scholarly journals Design, Synthesis, and Evaluation of Alkyl-Quinoxalin-2(1H)-One Derivatives as Anti-Quorum Sensing Molecules, Inhibiting Biofilm Formation in Aeromonas caviae Sch3

Molecules ◽  
2018 ◽  
Vol 23 (12) ◽  
pp. 3075 ◽  
Author(s):  
René Blöcher ◽  
Ariel Rodarte Ramírez ◽  
Graciela Castro-Escarpulli ◽  
Everardo Curiel-Quesada ◽  
Alicia Reyes-Arellano
Keyword(s):  
Carboxylic Acid ◽  
Quorum Sensing ◽  
Biofilm Formation ◽  
Bacterial Biofilm ◽  
Alternative Methods ◽  
Resistant Bacteria ◽  
Bacterial Strains ◽  
Design Synthesis ◽  
Bacterial Communication ◽  
Aeromonas Caviae

With the increasing antibiotic resistance of bacterial strains, alternative methods for infection control are in high demand. Quorum sensing (QS) is the bacterial communication system based on small molecules. QS is enables bacterial biofilm formation and pathogenic development. The interruption of QS has become a target for drug discovery, but remains in the early experimental phase. In this study, we synthesized a set of six compounds based on a scaffold (alkyl-quinoxalin-2(1H)-one), new in the anti-QS of Gram-negative bacteria Aeromonas caviae Sch3. By quantifying biofilm formation, we were able to monitor the effect of these compounds from concentrations of 1 to 100 µM. Significant reduction in biofilm formation was achieved by 3-hexylylquinoxalin-2(1H)-one (11), 3-hexylylquinoxalin-2(1H)-one-6-carboxylic acid (12), and 3-heptylylquinoxalin-2(1H)-one-6-carboxylic acid (14), ranging from 11% to 59% inhibition of the biofilm. This pilot study contributes to the development of anti-QS compounds to overcome the clinical challenge of resistant bacteria strains.

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