scholarly journals Plants Secrete Substances That Mimic Bacterial N-Acyl Homoserine Lactone Signal Activities and Affect Population Density-Dependent Behaviors in Associated Bacteria

2000 ◽  
Vol 13 (6) ◽  
pp. 637-648 ◽  
Author(s):  
Max Teplitski ◽  
Jayne B. Robinson ◽  
Wolfgang D. Bauer
Keyword(s):  
Chemical Nature ◽  
Higher Plants ◽  
Homoserine Lactone ◽  
Signal Molecules ◽  
Gram Negative Bacteria ◽  
Associated Bacteria ◽  
Gram Negative ◽  
Density Dependent ◽  
Reporter Strains ◽  
And Behavior

In gram-negative bacteria, many important changes in gene expression and behavior are regulated in a popula tion density-dependent fashion by N-acyl homoserine lac tone (AHL) signal molecules. Exudates from pea (Pisum sativum) seedlings were found to contain several separable activities that mimicked AHL signals in well-characterized bacterial reporter strains, stimulating AHL-regulated be haviors in some strains while inhibiting such behaviors in others. The chemical nature of the active mimic com pounds is currently unknown, but all extracted differently into organic solvents than common bacterial AHLs. Various species of higher plants in addition to pea were found to secrete AHL mimic activities. The AHL signal-mimic compounds could prove to be important in determining the outcome of interactions between higher plants and a diver sity of pathogenic, symbiotic, and saprophytic bacteria.

scholarly journals Quenching of acyl-homoserine lactone-dependent quorum sensing by enzymatic disruption of signal molecules.

2009 ◽  
Vol 56 (1) ◽  
Author(s):  
Robert Czajkowski ◽  
Sylwia Jafra
Keyword(s):  
Quorum Sensing ◽  
Pathogenic Bacteria ◽  
Degradation Products ◽  
Antibiotic Production ◽  
Quorum Quenching ◽  
Homoserine Lactone ◽  
Signal Molecules ◽  
Gram Negative Bacteria ◽  
Gram Negative ◽  
Animal Pathogens

Many Gram-positive and Gram-negative bacteria communicate using small diffusible signal molecules called autoinducers. This process, known as quorum sensing (QS), links cell density to the expression of genes as diverse as those associated with virulence factors production of plant and animal pathogens, bioluminescence, antibiotic production, sporulation or biofilm formation. In Gram-negative bacteria, this communication is mainly mediated by N-acyl-homoserine lactones (AHLs). It has been proven that inactivation of the signal molecules attenuates many of the processes controlled by QS. Enzymatic degradation of the signal molecules has been amply described. Two main classes of AHL-inactivating enzymes were identified: AHL lactonases which hydrolyse the lactone ring in AHLs, and AHL acylases (syn. AHL amidases) which liberate a free homoserine lactone and a fatty acid. Recently, AHL oxidoreductase, a novel type of AHL inactivating enzyme, was described. The activity of these enzymes results in silencing the QS-regulated processes, as degradation products cannot act as signal molecules. The ability to inactivate AHL (quorum quenching, QQ) might be useful in controlling virulence of many pathogenic bacteria.

Production and use of monoclonal antibodies for identification of Bradyrhizobium japonicum strains

1988 ◽  
Vol 34 (1) ◽  
pp. 88-92 ◽  
Author(s):  
D. Velez ◽  
J. D. Macmillan ◽  
L. Miller
Keyword(s):  
Monoclonal Antibodies ◽  
Bradyrhizobium Japonicum ◽  
Chemical Nature ◽  
Periodate Oxidation ◽  
Enzyme Linked Immunosorbent Assay ◽  
Gram Negative Bacteria ◽  
Bacterial Cells ◽  
Gram Negative ◽  
Polyclonal Antisera ◽  
Somatic Antigens

Thirteen murine hybridomas capable of producing monoclonal antibodies to somatic antigens on Bradyrhizobium japonicum were developed and an indirect enzyme-linked immunosorbent assay was used to test reactivity of the antibodies against 20 strains of B. japonicum. Although polyclonal antisera from mice immunized with strains of B. japonicum reacted with bacterial cells of all 20 strains, individual monoclonals were more specific. Some antibodies reacted with as few as 2 and one with as many as 11 strains. On the basis of reactivity with the set of 13 monoclonal antibodies, the 20 strains of B. japonicum could be divided arbitrarily into five groups. Three of five monoclonal antibodies tested reacted with bacteroids taken directly from soybean nodules. One monoclonal bound to cells of five species of Rhizobium, but none of the 13 reacted with gram-negative bacteria representing six other genera. Treatment of cells with reagents and heat indicated the chemical nature of the antigens to five of the monoclonals. Antigen reactive with one antibody was destroyed by periodate oxidation indicating that it was a polysaccharide. Two antigens were probably proteins as they could be digested by trypsin and denatured by heat. Two others were inactivated by all three treatments suggesting they were glycoproteins.

scholarly journals Regulation of Plant Mineral Nutrition by Signal Molecules

2021 ◽  
Vol 9 (4) ◽  
pp. 774
Author(s):  
Vipin Chandra Kalia ◽  
Chunjie Gong ◽  
Sanjay K. S. Patel ◽  
Jung-Kul Lee
Keyword(s):  
Signal Molecules ◽  
Gram Negative Bacteria ◽  
Human Beings ◽  
High Cell ◽  
Specific Chemical ◽  
Gram Negative ◽  
Plant Mineral Nutrition ◽  
Recent Developments ◽  
Cell Densities ◽  
Metabolic Activities

Microbes operate their metabolic activities at a unicellular level. However, it has been revealed that a few metabolic activities only prove beneficial to microbes if operated at high cell densities. These cell density-dependent activities termed quorum sensing (QS) operate through specific chemical signals. In Gram-negative bacteria, the most widely reported QS signals are acylhomoserine lactones. In contrast, a novel QS-like system has been elucidated, regulating communication between microbes and plants through strigolactones. These systems regulate bioprocesses, which affect the health of plants, animals, and human beings. This mini-review presents recent developments in the QS and QS-like signal molecules in promoting plant health.

scholarly journals β-Cyclodextrin Interaction with N-Hexanoyl Homoserine Lactone as Quorum Sensing Signal Produced in Gram-Negative Bacteria

2012 ◽  
Vol 37 (2) ◽  
pp. 315-318 ◽  
Author(s):  
Chigusa Okano ◽  
Marina Arai ◽  
Eri Nasuno ◽  
Ken-ichi Iimura ◽  
Tomohiro Morohoshi ◽  
...  
Keyword(s):  
Quorum Sensing ◽  
Homoserine Lactone ◽  
Gram Negative Bacteria ◽  
Gram Negative

Variations on a Theme: Diverse N-Acyl Homoserine Lactone-Mediated Quorum Sensing Mechanisms in Gram-Negative Bacteria

2006 ◽  
Vol 89 (3-4) ◽  
pp. 167-211 ◽  
Author(s):  
Debra Smith ◽  
Jin-Hong Wang ◽  
Jane E. Swatton ◽  
Peter Davenport ◽  
Bianca Price ◽  
...  
Keyword(s):  
Quorum Sensing ◽  
Homoserine Lactone ◽  
Acyl Homoserine Lactone ◽  
Gram Negative Bacteria ◽  
Gram Negative ◽  
Variations On A Theme

scholarly journals Eight Gram-negative bacteria are 10 000 times more sensitive to cationic detergents than to anionic detergents

2003 ◽  
Vol 49 (12) ◽  
pp. 775-779 ◽  
Author(s):  
Soumitra Rajagopal ◽  
Nicole Eis ◽  
Kenneth W Nickerson
Keyword(s):  
Sodium Dodecyl Sulfate ◽  
Cetyltrimethylammonium Bromide ◽  
Liquid Culture ◽  
Sodium Dodecyl ◽  
Homoserine Lactone ◽  
Luria Bertani ◽  
Gram Negative Bacteria ◽  
Gram Negative ◽  
Cationic Detergents ◽  
Dodecyl Sulfate

In liquid culture, eight typical Gram-negative bacteria were ca. 10 000-fold more sensitive to cationic detergents than to the anionic detergent sodium dodecyl sulfate. Cetyltrimethylammonium bromide (CTAB) was inhibitory at concentrations ranging from 0.0006% to 0.01%. Four pseudomonads able to form biofilms were ca. 1000-fold more resistant to CTAB on Luria–Bertani agar plates than they were in liquid culture. A lasI mutant of Pseudomonas aerugi nosa was only able to tolerate 0.1% CTAB on Luria–Bertani agar plates but could tolerate 5% CTAB when supplemented with homoserine lactone containing culture supernatants.Key words: sodium dodecyl sulfate, cetyltrimethylammonium bromide, bacterial detergent resistance, homoserine lactones, Pseudomonas biofilms.

Production ofN-acylhomoserine lactone signal molecules by gram-negative soil-borne and plant-associated bacteria

2003 ◽  
Vol 48 (6) ◽  
pp. 794-798 ◽  
Author(s):  
M. Vfselova ◽  
M. Kholmeckaya ◽  
S. Klein ◽  
E. Voronina ◽  
V. Lipasova ◽  
...  
Keyword(s):  
Signal Molecules ◽  
Associated Bacteria ◽  
Gram Negative ◽  
Acylhomoserine Lactone

BLOOD GROUP ACTIVE GRAM-NEGATIVE BACTERIA AND HIGHER PLANTS*

2006 ◽  
Vol 97 (1) ◽  
pp. 104-110 ◽  
Author(s):  
Georg F. Springer ◽  
Peter Williamson ◽  
Barbara L. Readler
Keyword(s):  
Blood Group ◽  
Higher Plants ◽  
Gram Negative Bacteria ◽  
Gram Negative

scholarly journals Dominance of Vibrio fischeri in Secreted Mucus outside the Light Organ of Euprymna scolopes: the First Site of Symbiont Specificity

2003 ◽  
Vol 69 (7) ◽  
pp. 3932-3937 ◽  
Author(s):  
Spencer V. Nyholm ◽  
Margaret J. McFall-Ngai
Keyword(s):  
Fluorescent Protein ◽  
Vibrio Fischeri ◽  
Signal Molecules ◽  
Natural Seawater ◽  
Gram Negative Bacteria ◽  
Light Organ ◽  
Bacterial Cells ◽  
Euprymna Scolopes ◽  
Gram Negative ◽  
Green Fluorescent

ABSTRACT Previous studies of the Euprymna scolopes-Vibrio fischeri symbiosis have demonstrated that, during colonization, the hatchling host secretes mucus in which gram-negative environmental bacteria amass in dense aggregations outside the sites of infection. In this study, experiments with green fluorescent protein-labeled symbiotic and nonsymbiotic species of gram-negative bacteria were used to characterize the behavior of cells in the aggregates. When hatchling animals were exposed to 103 to 106 V. fischeri cells/ml added to natural seawater, which contains a mix of approximately 106 nonspecific bacterial cells/ml, V. fischeri cells were the principal bacterial cells present in the aggregations. Furthermore, when animals were exposed to equal cell numbers of V. fischeri (either a motile or a nonmotile strain) and either Vibrio parahaemolyticus or Photobacterium leiognathi, phylogenetically related gram-negative bacteria that also occur in the host's habitat, the symbiont cells were dominant in the aggregations. The presence of V. fischeri did not compromise the viability of these other species in the aggregations, and no significant growth of V. fischeri cells was detected. These findings suggested that dominance results from the ability of V. fischeri either to accumulate or to be retained more effectively within the mucus. Viability of the V. fischeri cells was required for both the formation of tight aggregates and their dominance in the mucus. Neither of the V. fischeri quorum-sensing compounds accumulated in the aggregations, which suggested that the effects of these small signal molecules are not critical to V. fischeri dominance. Taken together, these data provide evidence that the specificity of the squid-vibrio symbiosis begins early in the interaction, in the mucus where the symbionts aggregate outside of the light organ.

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