Characterization of the Quorum Sensing Regulon in Acidithiobacillus ferrooxidans

2013 ◽  
Vol 825 ◽  
pp. 129-132 ◽  
Author(s):  
Sigde Mamani ◽  
Yan Denis ◽  
Danielle Moinier ◽  
Mohamad Sabbah ◽  
Laurent Soulère ◽  
...  
Keyword(s):  
Cell Adhesion ◽  
Quorum Sensing ◽  
Acidithiobacillus Ferrooxidans ◽  
Operating Cost ◽  
Second Step ◽  
Low Grade ◽  
Mineral Surface ◽  
Homoserine Lactones ◽  
The Moment

Bioleaching is the solubilization of metals from ores by microorganisms. This process is more efficient than conventional methods in the metal recovery from low grade ores while decreasing the operating cost and the environmental impact. Among the bioleaching bacteria, the Gram-negative chemolithoautotrophic acidophilic Acidithiobacillus ferrooxidans has the ability to adhere to mineral surface and to form biofilm. The genes involved in the production of this biofilm are controlled by a cellular communication system called Quorum Sensing (QS). The QS occurs mainly through the production of acyl homoserine lactones (AHLs). A functional QS system has been identified in At. ferrooxidans with an acyl synthase (AfeI) and a transcriptional regulator (AfeR). Here, our purpose is to characterize the quorum sensing regulon and particularly the genes involved in biofilm formation in At. ferrooxidans. This has been done by cell adhesion experiments comparing At. ferrooxidans grown with or without Tetrazol, an AHL analogue that activates the cell adhesion to mineral surface. The second step has been to compare the expression of some genes predicted to be involved in the QS regulon in At. ferrooxidans grown in the presence/absence of Tetrazol using real-time PCR. These two different strategies are expected to give insight on the moment at which the At. ferrooxidans QS regulon is switched on. The formation of biofilm could improve the bioleaching operation and therefore the understanding of the QS regulon is of primordial importance.

scholarly journals Characterization of a Phosphotriesterase-Like Lactonase fromSulfolobus solfataricusand Its Immobilization for Disruption of Quorum Sensing

2010 ◽  
Vol 77 (4) ◽  
pp. 1181-1186 ◽  
Author(s):  
Filomena S. W. Ng ◽  
Daniel M. Wright ◽  
Stephen Y. K. Seah
Keyword(s):  
Quorum Sensing ◽  
Virulence Factors ◽  
Acyl Chain ◽  
Quorum Quenching ◽  
Homoserine Lactone ◽  
Homoserine Lactones ◽  
Specificity Constant ◽  
Chain Lengths ◽  
Quorum Sensing Signals

ABSTRACTSsoPox, a bifunctional enzyme with organophosphate hydrolase andN-acyl homoserine lactonase activities from the hyperthermophilic archaeonSulfolobus solfataricus, was overexpressed and purified from recombinantPseudomonas putidaKT2440 with a yield of 9.4 mg of protein per liter of culture. The enzyme has a preference forN-acyl homoserine lactones (AHLs) with acyl chain lengths of at least 8 carbon atoms, mainly due to lowerKmvalues for these substrates. The highest specificity constant obtained was forN-3-oxo-decanoyl homoserine lactone (kcat/Km= 5.5 × 103M−1·s−1), but SsoPox can also degradeN-butyryl homoserine lactone (C4-HSL) andN-oxo-dodecanoyl homoserine lactone (oxo-C12-HSL), which are important for quorum sensing in ourPseudomonas aeruginosamodel system. WhenP. aeruginosaPAO1 cultures were grown in the presence of SsoPox-immobilized membranes, the production of C4-HSL- and oxo-C12-HSL-regulated virulence factors, elastase, protease, and pyocyanin were significantly reduced. This is the first demonstration that immobilized quorum-quenching enzymes can be used to attenuate the production of virulence factors controlled by quorum-sensing signals.

scholarly journals Characterization of the Sinorhizobium meliloti sinR/sinI Locus and the Production of Novel N-Acyl Homoserine Lactones

2002 ◽  
Vol 184 (20) ◽  
pp. 5686-5695 ◽  
Author(s):  
Melanie M. Marketon ◽  
Matthew R. Gronquist ◽  
Anatol Eberhard ◽  
Juan E. González
Keyword(s):  
Quorum Sensing ◽  
Sinorhizobium Meliloti ◽  
Short Chain ◽  
Homoserine Lactones ◽  
Sensing System ◽  
Acyl Homoserine Lactones ◽  
Quorum Sensing System ◽  
Acyl Chains ◽  
Novel Structures

ABSTRACT Sinorhizobium meliloti is a soil bacterium which can establish a nitrogen-fixing symbiosis with the legume Medicago sativa. Recent work has identified a pair of genes, sinR and sinI, which represent a potential quorum-sensing system and are responsible for the production of N-acyl homoserine lactones (AHLs) in two S. meliloti strains, Rm1021 and Rm41. In this work, we characterize the sinRI locus and show that these genes are responsible for the synthesis of several long-chain AHLs ranging from 12 to 18 carbons in length. Four of these, 3-oxotetradecanoyl HL, 3-oxohexadecenoyl HL, hexadecenoyl HL, and octadecanoyl HL, have novel structures. This is the first report of AHLs having acyl chains longer than 14 carbons. We show that a disruption in sinI eliminates these AHLs and that a sinR disruption results in only basal levels of the AHLs. Moreover, the same sinI and sinR mutations also lead to a decrease in the number of pink nodules during nodulation assays, as well as a slight delay in the appearance of pink nodules, indicating a role for quorum sensing in symbiosis. We also show that sinI and sinR mutants are still capable of producing several short-chain AHLs, one of which was identified as octanoyl HL. We believe that these short-chain AHLs are evidence of a second quorum-sensing system in Rm1021, which we refer to here as the mel system, for “S. meliloti.”

Characterization of quorum sensing genes and N-acyl homoserine lactones in Citrobacter amalonaticus strain YG6

Gene ◽  
2019 ◽  
Vol 684 ◽  
pp. 58-69 ◽  
Author(s):  
Heng-Leong Kher ◽  
Thiba Krishnan ◽  
Vengadesh Letchumanan ◽  
Kar-Wai Hong ◽  
Kah-Yan How ◽  
...  
Keyword(s):  
Quorum Sensing ◽  
Homoserine Lactones ◽  
Acyl Homoserine Lactones ◽  
Citrobacter Amalonaticus

Scanning Electron Microscope Study of Bacteria on Mineral Surfaces

1976 ◽  
Vol 34 ◽  
pp. 130-131
Author(s):  
V.K. Berry
Keyword(s):  
Oxidation Reaction ◽  
Electron Microscope Study ◽  
Elemental Sulfur ◽  
Thiobacillus Ferrooxidans ◽  
Physical Contact ◽  
Metal Sulfides ◽  
Low Grade ◽  
Mineral Surfaces ◽  
Mineral Surface ◽  
Scanning Electron Microscope Study

There are two strains of bacteria viz. Thiobacillus thiooxidansand Thiobacillus ferrooxidanswidely mentioned to play an important role in the leaching process of low-grade ores. Another strain used in this study is a thermophile and is designated Caldariella .These microorganisms are acidophilic chemosynthetic aerobic autotrophs and are capable of oxidizing many metal sulfides and elemental sulfur to sulfates and Fe2+ to Fe3+. The necessity of physical contact or attachment by bacteria to mineral surfaces during oxidation reaction has not been fairly established so far. Temple and Koehler reported that during oxidation of marcasite T. thiooxidanswere found concentrated on mineral surface. Schaeffer, et al. demonstrated that physical contact or attachment is essential for oxidation of sulfur.

Comparison of Immunological and Functional Assays for Measurement of Soluble Fibrin

1995 ◽  
Vol 74 (02) ◽  
pp. 673-679 ◽  
Author(s):  
C E Dempfle ◽  
S A Pfitzner ◽  
M Dollman ◽  
K Huck ◽  
G Stehle ◽  
...  
Keyword(s):  
Venous Thrombosis ◽  
Low Grade ◽  
Plasma Samples ◽  
Normal Range ◽  
Soluble Fibrin ◽  
Discriminating Power ◽  
Fibrin Monomer ◽  
Cerebral Ischemic

SummaryVarious assays have been developed for quantitation of soluble fibrin or fibrin monomer in clinical plasma samples, since this parameter directly reflects in vivo thrombin action on fibrinogen. Using plasma samples from healthy blood donors, patients with cerebral ischemic insult, patients with septicemia, and patients with venous thrombosis, we compared two immunologic tests using monoclonal antibodies against fibrin-specific neo-epitopes, and two functional tests based on the cofactor activity of soluble fibrin complexes in tPA-induced plasminogen activation. Test A (Enzymun®-Test FM) showed the best discriminating power among normal range and pathological samples. Test B (Fibrinostika® soluble fibrin) clearly separated normal range from pathological samples, but failed to discriminate among samples from patients with low grade coagulation activation in septicemia, and massive activation in venous thrombosis. Functional test C (Fibrin monomer test Behring) displayed good discriminating power between normal and pathological range samples, and correlated with test A (r = 0.61), whereas assay D (Coa-Set® Fibrin monomer) showed little discriminating power at values below 10 μg/ml and little correlation with other assays. Standardization of assays will require further characterization of analytes detected.

scholarly journals Evidence of Quorum Sensing in Cyanobacteria by Homoserine Lactones: The Origin of Blooms

Water ◽  
2021 ◽  
Vol 13 (13) ◽  
pp. 1831
Author(s):  
Natalia Herrera ◽  
Fernando Echeverri
Keyword(s):  
Cell Proliferation ◽  
Quorum Sensing ◽  
Microcystis Aeruginosa ◽  
Industrial Effluents ◽  
Cyanobacterial Blooms ◽  
Cylindrospermopsis Raciborskii ◽  
Bacterial Communication ◽  
Homoserine Lactones ◽  
Exogenous Compounds ◽  
Almost All

Although several theories have been postulated to explain cyanobacterial blooms, their biochemical origin has not yet been found. In this work, we explore the existence of bacterial communication, called quorum sensing, in Microcystis aeruginosa and Cylindrospermopsis raciborskii. Thus, the application of several known acylhomoserine lactones to cultures of both cyanobacteria causes profound metabolic. At 72 h post-application, some of them produced substantial increases in cell proliferation, while others were inhibitors. There was a correlation with colony-forming activity for most of them. According to ELISA analysis, the microcystin levels were increased with some lactones. However, there was a clear difference between M. aeruginosa and C. raciborskii culture since, in the first one, there was an inducing effect on cell proliferation, while in C. raciborskii, the effects were minor. Besides, there were compound inhibitors and inducers of microcystins production in M. aeruginosa, but almost all compounds were only inducers of saxitoxin production in C. raciborskii. Moreover, each lactone appears to be involved in a specific quorum sensing process. From these results, the formation of cyanobacterial blooms in dams and reservoirs could be explained since lactones may come from cyanobacteria and other sources as bacterial microflora-associated or exogenous compounds structurally unrelated to lactones, such as drugs, industrial effluents, and agrochemicals.

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