Production of quorum-sensing-related signal molecules by epiphytic bacteria inhabiting wheat heads

2006 ◽  
Vol 52 (5) ◽  
pp. 411-418 ◽  
Author(s):  
Shigenobu Yoshida ◽  
Linda L Kinkel ◽  
Hirosuke Shinohara ◽  
Nobutaka Numajiri ◽  
Syuntaro Hiradate ◽  
...  
Keyword(s):  
Quorum Sensing ◽  
Population Size ◽  
Signal Molecules ◽  
Rrna Gene ◽  
Culturable Bacteria ◽  
Bacterial Isolates ◽  
16S Rrna Gene Sequences ◽  
Pantoea Ananatis ◽  
Signal Molecule ◽  
Layer Chromatography

The production of quorum-sensing-related signal molecules (QSRMs) among culturable bacteria comprising the community on wheat heads was investigated. The taxonomic position of 186 bacterial isolates obtained from ten heads was inferred based on 16S rRNA gene sequences, and their QSRM production was determined using two bioreporter strains of N-acylhomoserine lactones. Approximately 33% of isolates produced QSRMs, though the proportion of QSRM-producing isolates on a wheat head was significantly negatively correlated with population size. Most of the producing isolates were Pantoea species, most commonly Pantoea ananatis. Furthermore, the proportion of Pantoea ananatis that produced QSRMs was significantly negatively correlated with the number of bacterial genera (community richness) on each head. Finally, community richness was positively correlated with population size. Qualitative analysis using thin-layer-chromatography revealed that the QSRMs of Pantoea isolates were composed of at least two compounds. This is the first report indicating that Pantoea ananatis isolates inhabiting wheat heads are capable of producing QSRMs. QSRM production by Pantoea spp. may contribute to the predominance of this genus on wheat heads, particularly at relatively low population densities and community diversity.Key words: quorum sensing, signal molecule, epiphyte, wheat head, Pantoea spp.

Novel bacteria degrading N-acylhomoserine lactones and their use as quenchers of quorum-sensing-regulated functions of plant-pathogenic bacteria

Microbiology ◽  
2003 ◽  
Vol 149 (8) ◽  
pp. 1981-1989 ◽  
Author(s):  
Stéphane Uroz ◽  
Cathy D'Angelo-Picard ◽  
Aurélien Carlier ◽  
Miena Elasri ◽  
Carine Sicot ◽  
...  
Keyword(s):  
Quorum Sensing ◽  
Pathogenic Bacteria ◽  
Rhodococcus Erythropolis ◽  
Homoserine Lactone ◽  
Signal Molecules ◽  
In Planta ◽  
Signal Molecule ◽  
Violacein Production ◽  
Regulated Functions

Bacteria degrading the quorum-sensing (QS) signal molecule N-hexanoylhomoserine lactone were isolated from a tobacco rhizosphere. Twenty-five isolates degrading this homoserine lactone fell into six groups according to their genomic REP-PCR and rrs PCR-RFLP profiles. Representative strains from each group were identified as members of the genera Pseudomonas, Comamonas, Variovorax and Rhodococcus. All these isolates degraded N-acylhomoserine lactones other than the hexanoic acid derivative, albeit with different specificity and kinetics. One of these isolates, Rhodococcus erythropolis strain W2, was used to quench QS-regulated functions of other microbes. In vitro, W2 strongly interfered with violacein production by Chromobacterium violaceum, and transfer of pathogenicity in Agrobacterium tumefaciens. In planta, R. erythropolis W2 markedly reduced the pathogenicity of Pectobacterium carotovorum subsp. carotovorum in potato tubers. These series of results reveal the diversity of the QS-interfering bacteria in the rhizosphere and demonstrate the validity of targeting QS signal molecules to control pathogens with natural bacterial isolates.

Herbiconiux moechotypicola sp. nov., a xylanolytic bacterium isolated from the gut of hairy long-horned toad beetles, Moechotypa diphysis (Pascoe)

2012 ◽  
Vol 62 (1) ◽  
pp. 90-95 ◽  
Author(s):  
Byung-Chun Kim ◽  
Doo-Sang Park ◽  
Hyangmi Kim ◽  
Hyun-Woo Oh ◽  
Kang Hyun Lee ◽  
...  
Keyword(s):  
Genomic Dna ◽  
Type Strain ◽  
Novel Species ◽  
Rrna Gene ◽  
Culturable Bacteria ◽  
16S Rrna Gene Sequences ◽  
Cellular Fatty Acids ◽  
The Family ◽  
Diamino Acid ◽  
Isoprenoid Quinones

A novel Gram-positive, non-motile, rod-shaped bacterium, designated strain RB-62T, was isolated during a study of culturable bacteria from the gut of Moechotypa diphysis (Pascoe) and its taxonomic position was investigated. Strain RB-62T grew at 15–30 °C and pH 5.0–8.5. The isoprenoid quinones were menaquinones MK-11 (77.1 %), MK-10 (11.7 %) and MK-12 (11.2 %). The major cellular fatty acids were anteiso-C15 : 0 (34.6 %), anteiso-C17 : 0 (29.8 %), iso-C16 : 0 (17.0 %) and cyclohexyl-C17 : 0 (11.4 %). The diagnostic diamino acid of the cell-wall peptidoglycan was 2,4-diaminobutyric acid. The G+C content of the genomic DNA of strain RB-62T was 70.3 mol%. Phylogenetic analysis based on 16S rRNA gene sequences showed that strain RB-62T was affiliated with the genus Herbiconiux cluster within the family Microbacteriaceae, and was related most closely to Herbiconiux ginsengi wged11T (98.08 % similarity). The level of DNA–DNA relatedness between strain RB-62T and H. ginsengi wged11T was 43.2 % (reciprocal 66.7 %). Phenotypic and phylogenetic characteristics clearly distinguished strain RB-62T from recognized species of the genus Herbiconiux. Based on data from the present polyphasic study, strain RB-62T is considered to represent a novel species of the genus Herbiconiux, for which the name Herbiconiux moechotypicola sp. nov. is proposed. The type strain is RB-62T ( = KCTC 19653T = JCM 16117T).

scholarly journals Extensive Diversity of Ionizing-Radiation-Resistant Bacteria Recovered from Sonoran Desert Soil and Description of Nine New Species of the Genus Deinococcus Obtained from a Single Soil Sample

2005 ◽  
Vol 71 (9) ◽  
pp. 5225-5235 ◽  
Author(s):  
Fred A. Rainey ◽  
Keren Ray ◽  
Margarida Ferreira ◽  
Bridget Z. Gatz ◽  
M. Fernanda Nobre ◽  
...  
Keyword(s):  
Ionizing Radiation ◽  
Soil Sample ◽  
Sonoran Desert ◽  
Desert Soil ◽  
Resistant Bacteria ◽  
Rrna Gene ◽  
Culturable Bacteria ◽  
Bacterial Isolates ◽  
Arid Soil ◽  
Radiation Resistant

ABSTRACT The ionizing-radiation-resistant fractions of two soil bacterial communities were investigated by exposing an arid soil from the Sonoran Desert and a nonarid soil from a Louisiana forest to various doses of ionizing radiation using a 60Co source. The numbers of surviving bacteria decreased as the dose of gamma radiation to which the soils were exposed increased. Bacterial isolates surviving doses of 30 kGy were recovered from the Sonoran Desert soil, while no isolates were recovered from the nonarid forest soil after exposure to doses greater than 13 kGy. The phylogenetic diversities of the surviving culturable bacteria were compared for the two soils using 16S rRNA gene sequence analysis. In addition to a bacterial population that was more resistant to higher doses of ionizing radiation, the diversity of the isolates was greater in the arid soil. The taxonomic diversity of the isolates recovered was found to decrease as the level of ionizing-radiation exposure increased. Bacterial isolates of the genera Deinococcus, Geodermatophilus, and Hymenobacter were still recovered from the arid soil after exposure to doses of 17 to 30 kGy. The recovery of large numbers of extremely ionizing-radiation-resistant bacteria from an arid soil and not from a nonarid soil provides further ecological support for the hypothesis that the ionizing-radiation resistance phenotype is a consequence of the evolution of other DNA repair systems that protect cells against commonly encountered environmental stressors, such as desiccation. The diverse group of bacterial strains isolated from the arid soil sample included 60 Deinococcus strains, the characterization of which revealed nine novel species of this genus.

scholarly journals The Plant Pathogen Pantoea ananatis Produces N-Acylhomoserine Lactone and Causes Center Rot Disease of Onion by Quorum Sensing

2007 ◽  
Vol 189 (22) ◽  
pp. 8333-8338 ◽  
Author(s):  
Tomohiro Morohoshi ◽  
Yuta Nakamura ◽  
Go Yamazaki ◽  
Akio Ishida ◽  
Norihiro Kato ◽  
...  
Keyword(s):  
Quorum Sensing ◽  
Biofilm Formation ◽  
Receptor Gene ◽  
Homoserine Lactone ◽  
Pantoea Ananatis ◽  
Signal Molecule ◽  
Acylhomoserine Lactone ◽  
Sensing System ◽  
Quorum Sensing System ◽  
Rot Disease

ABSTRACT A number of gram-negative bacteria have a quorum-sensing system and produce N-acyl-l-homoserine lactone (AHL) that they use them as a quorum-sensing signal molecule. Pantoea ananatis is reported as a common colonist of wheat heads at ripening and causes center rot of onion. In this study, we demonstrated that P. ananatis SK-1 produced two AHLs, N-hexanoyl-l-homoserine lactone (C6-HSL) and N-(3-oxohexanoyl)-l-homoserine lactone (3-oxo-C6-HSL). We cloned the AHL-synthase gene (eanI) and AHL-receptor gene (eanR) and revealed that the deduced amino acid sequence of EanI/EanR showed high identity to those of EsaI/EsaR from P. stewartii. EanR repressed the ean box sequence and the addition of AHLs resulted in derepression of ean box. Inactivation of the chromosomal eanI gene in SK-1 caused disruption of exopolysaccharide (EPS) biosynthesis, biofilm formation, and infection of onion leaves, which were recovered by adding exogenous 3-oxo-C6-HSL. These results demonstrated that the quorum-sensing system involved the biosynthesis of EPS, biofilm formation, and infection of onion leaves in P. ananatis SK-1.

scholarly journals Universal 16s rRNA Primers BD1 For Soil Microbial Community Analysis

2006 ◽  
Vol 4 (4) ◽  
pp. 32-37
Author(s):  
Elisaveta V Korostik ◽  
Alexander G Pinaev ◽  
Gulnar A Akhtemova ◽  
Evgeniy E Andronov
Keyword(s):  
Microbial Community ◽  
16S Rrna ◽  
Community Analysis ◽  
Microbial Community Analysis ◽  
Rrna Gene ◽  
Community Studies ◽  
Bacterial Isolates ◽  
16S Rrna Gene Sequences ◽  
Soil Microbial ◽  
16S Rrna Clone Library

New universal 16S rRNa primers were constructed and tested. These primers allow identifying correct taxonomic position of bacterial isolates and were shown to be useful in microbial community studies. The primers enable to detect the vast majority of unique 16S rRNa gene sequences. In the study 160 restriction types were found in 16S rRNa clone library (190 clones).

scholarly journals Penapisan Bakteri Penghambat Fusarium yang Diisolasi dari Cairan Kantung Semar (Nepenthes sp.)

2020 ◽  
Vol 25 (4) ◽  
pp. 627-635
Author(s):  
Siti Meliah ◽  
Annisa Wahyu Hardiyanti ◽  
Ni’ma Haida ◽  
Gita Azizah Putri ◽  
Erny Qurotul Ainy
Keyword(s):  
16S Rrna ◽  
16S Rrna Gene ◽  
Agar Medium ◽  
Cultivated Plants ◽  
Rrna Gene ◽  
Malt Extract ◽  
Bacterial Isolates ◽  
Gene Sequences ◽  
16S Rrna Gene Sequences ◽  
Fusarium Sp

The genus Fusarium sp. is a pathogenic fungal for many cultivated plants. The bacteria isolated from monkey cup (Nepenthes sp.) fluid possess the ability to produce hydrolytic enzyme, such as chitinase which can be utilized to inhibit the growth of mycelia of pathogenic fungi. The aims of this study are to isolate bacteria from monkey cup liquid, to test their abilities to produce protease, chitinase, and cellulase, as well as their abilities to inhibit Fusarium. The bacteria were isolated using serial dilution method on Reasoner’s 2A agar medium. Enzymatic activities of bacterial isolates were determined by inoculating them on tested medium supplemented with casein protein, chitin, and cellulose, whereas their antifungal activities were assayed using a direct confrontation method between tested bacterial isolates and pathogenic fungal on Malt Extract Agar medium. Molecular identification of bacteria with antifungal activity was performed by analyzing the 16S rRNA gene sequences. Isolation process of bacteria from monkey cup fluid resulted in 99 bacterial isolates with the ability to produce either protease, chitinase, and/or cellulose enzymes. A total of 37 bacterial isolates were capable of producing at least two hydrolytic enzymes. Antifungal assay of those bacteria showed that as many as 25 isolates have the ability to inhibit the growth of Fusarium sp. Based on the analysis of 16S rRNA gene sequences revealed that those isolates were closely related to three Burkholderia species, namely B. arboris, B. contaminans, and B. rijonensis. Keywords: antifungal, Burkholderia, chitinase, cellulaseN, epenthes, protease

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 Quorum sensing and the population-dependent control of virulence

2000 ◽  
Vol 355 (1397) ◽  
pp. 667-680 ◽  
Author(s):  
Paul Williams ◽  
Miguel Camara ◽  
Andrea Hardman ◽  
Simon Swift ◽  
Deborah Milton ◽  
...  
Keyword(s):  
Quorum Sensing ◽  
Population Density ◽  
Cell Population ◽  
Cell Communication ◽  
Immunomodulatory Activity ◽  
Signal Molecules ◽  
Dependent Manner ◽  
Virulence Determinants ◽  
Signal Molecule ◽  
Cell Cell

One crucial feature of almost all bacterial infections is the need for the invading pathogen to reach a critical cell population density sufficient to overcome host defences and establish the infection. Controlling the expression of virulence determinants in concert with cell population density may therefore confer a significant survival advantage on the pathogen such that the host is overwhelmed before a defence response can be fully initiated. Many different bacterial pathogens are now known to regulate diverse physiological processes including virulence in a cell–density–dependent manner through cell–cell communication. This phenomenon, which relies on the interaction of a diffusible signal molecule (e.g. an N –acylhomoserine lactone) with a sensor or transcriptional activator to couple gene expression with cell population density, has become known as ‘quorum sensing’ . Although the size of the ‘quorum’ is likely to be highly variable and influenced by the diffusibility of the signal molecule within infected tissues, nevertheless quorum–sensing signal molecules can be detected in vivo in both experimental animal model and human infections. Furthermore, certain quorum–sensing molecules have been shown to possess pharmacological and immunomodulatory activity such that they may function as virulence determinants per se . As a consequence, quorum sensing constitutes a novel therapeutic target for the design of small molecular antagonists capable of attenuating virulence through the blockade of bacterial cell–cell communication.

scholarly journals Amylolytic ability of bacteria isolated from termite (Coptotermes sp.) gut

2018 ◽  
Vol 23 (1) ◽  
pp. 14 ◽  
Author(s):  
Putri Dwi Mulyani ◽  
Radhiyah Mardhiyah Hamid ◽  
Rifqi Zahroh Janatunaim ◽  
Yekti Asih Purwestri
Keyword(s):  
Amylase Activity ◽  
Rrna Gene ◽  
Optimum Temperature ◽  
Bacterial Isolates ◽  
16S Rrna Gene Sequences ◽  
Clear Zone ◽  
Optimum Ph ◽  
Iodine Test ◽  
Brevibacillus Parabrevis

BSR 2, BSR 3, BSR 8, and BSR 9, different bacteria isolated from the termite gut, have been shown to possess cellulolytic activities, but their amylolytic ability has heretofore been unknown. This study attempted to fill in this knowledge gap. The formation of a clear zone using the iodine test showed that the bacteria were able to produce and secrete amylase. Based on the results, the best cultivation times for strains BSR 2, BSR 3, BSR 8, and BSR 9 were 6, 3, 2, and 2 d, respectively, yielding amylase activities of 2.59 ± 0.13 U/mg, 2.00 ± 0.08 U/mg, 1.67 ± 0.10 U/mg, and 1.55 ± 0.12 U/mg, respectively. BSR 2 had the highest amylase activity compared with the other bacterial isolates. The optimum ph for bacterial amylase activity of BSR 2 was 7.0, and the optimum temperature was 40°C. The molecular characterization of isolates BSR 2, BSR 3, BSR 8, and BSR 9 was based on 16S rRNA gene sequences. Isolates BSR 8 and BSR 9 were thus identified as Brevibacillus parabrevis and Brevibacillus sp. With similarities amounting to 92.48% and 95.91%, while the BSR 3 isolate was identified as Pseudomonas alcaligenes with a similarity of 94.29%, and the BSR 2 isolate could not be identified yet.

Antipathogenic Activity of Acroporid Bacterial Symbionts Against Brown Band Disease-Associated Bacteria

2021 ◽  
Vol 16 (2) ◽  
pp. 65-74
Author(s):  
Rosa Amalia ◽  
Diah Ayuningrum ◽  
Agus Sabdono ◽  
Ocky Karna Radjasa
Keyword(s):  
16S Rrna ◽  
16S Rrna Gene ◽  
Rrna Gene ◽  
Bacterial Isolates ◽  
16S Rrna Gene Sequences ◽  
Coral Diseases ◽  
Associated Bacteria ◽  
Brown Band ◽  
The 16S Rrna Gene ◽  
Brown Band Disease

The coral reefs’ condition in most regions in Indonesia has been declining due to coral diseases, such as Brown Band Disease (BrBD). A treatment for BrBD involves the use of biological control agents that have antagonistic properties against disease-causing agents. This study aimed to isolate bacteria from healthy hard coral, those associated with BrBD, and those that had bioactivities against BrBD. Sampling and identification of corals and BrBD were carried out in March 2015 at the Marine National Park of Karimunjawa. Bacteria from healthy and infected corals were isolated and purified. The isolates were subjected to antipathogenic assay using overlay and agar diffusion methods. Finally, molecular identification of active bacteria was carried out using the 16S rRNA gene amplification. As many as 57 bacterial isolates were obtained from healthy coral, as well as four bacterial isolates from coral with BrBD symptoms. A total of 15 bacterial isolates (26%) showed antipathogenic activity against BrBD-associated bacteria. Three isolates with the strongest antipathogenic activities, i.e., GAMSH 3, KASH 6, and TAPSH 1 were identified by 16S rRNA gene sequences. The results showed that they were aligned to Virgibacillus marismortui (97%), Oceanobacillus iheyensis (97%), and Bacillus cereus (96%), respectively.

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