Publications by authors named "Devescovi G"

Endophytes are microorganisms that live inside plants and are often beneficial for the host. is a novel bacterial genus that includes several species that are diazotrophic and plant associated. This study revealed two quorum sensing-related LuxR solos, designated LoxR and PsrR, in the plant endophyte sp.

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Article Synopsis
  • Many species produce secondary metabolites that can have important biological functions and real-world uses.
  • This study focused on a specific bacterium's quorum sensing (QS) mechanism, regulated by AHLs, and created mutants to analyze their biological activities.
  • Findings showed that the AHLs-deficient mutant had significantly lower antagonistic activity and enzyme production compared to the wild type, while the complemented mutant regained much of these activities, highlighting the role of AHLs in regulating biological functions.
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  • Azelaic acid is a dicarboxylic acid found in cereals that recently shows potential in plant-bacteria interactions and can be used by certain bacteria as a carbon and energy source.
  • In this research, a specific bacterium, DSM 9128, is used to investigate how it degrades azelaic acid and how it reacts to it genetically.
  • The study reveals that mutations in specific genes hinder the growth of bacteria in azelaic acid and identifies a regulator named AzeR that responds to azelaic acid, which is limited to certain bacteria that can utilize it.
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Many plant bacterial pathogens monitor their group behaviour and their population density via production of N-acyl homoserine lactone signals which regulate the expression of several genes via the LuxI/R homologs. This regulatory network, termed quorum sensing (QS), is present in the soybean bacterial pathogen Pseudomonas savastanoi pv glycinea (Psg). The sequenced genomes of two strains of Psg, race 4 and B076, contain an N-acyl homoserine lactone (AHL) based LuxI/R QS system named AhlI/R.

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In a number of compatible plant-bacterium interactions, a rise in apoplastic Ca levels is observed, suggesting that Ca represents an important environmental clue, as reported for bacteria infecting mammalians. We demonstrate that Ca entry in Pseudomonas savastanoi pv. savastanoi (Psav) strain DAPP-PG 722 is mediated by a Na /Ca exchanger critical for virulence.

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Plants intimately associate with diverse bacteria. Plant-associated bacteria have ostensibly evolved genes that enable them to adapt to plant environments. However, the identities of such genes are mostly unknown, and their functions are poorly characterized.

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() is an emerging plant pathogen causing sheath brown rot in rice, as well as diseases in other gramineae food crops including maize, sorghum and wheat. possesses two conserved -acyl homoserine lactone (AHL) quorum sensing (QS) systems called PfvI/R and PfsI/R, which are repressed by RsaL and RsaM, respectively. The two systems are not hierarchically organized and are involved in plant virulence.

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The life cycle of bacterial phytopathogens consists of a benign epiphytic phase, during which the bacteria grow in the soil or on the plant surface, and a virulent endophytic phase involving the penetration of host defenses and the colonization of plant tissues. Innovative strategies are urgently required to integrate copper treatments that control the epiphytic phase with complementary tools that control the virulent endophytic phase, thus reducing the quantity of chemicals applied to economically and ecologically acceptable levels. Such strategies include targeted treatments that weaken bacterial pathogens, particularly those inhibiting early infection steps rather than tackling established infections.

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In , the purple pigment violacein is under positive regulation by the -acylhomoserine lactone CviI/R quorum sensing system and negative regulation by an uncharacterized putative repressor. In this study we report that the biosynthesis of violacein is negatively controlled by a novel repressor protein, VioS. The violacein operon is regulated negatively by VioS and positively by the CviI/R system in both and in a heterologous genetic background.

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infections represent a serious threat to worldwide health. Proline-rich antimicrobial peptides (PR-AMPs), a particular group of peptide antibiotics, have demonstrated activity against strains. Here we show that the mammalian PR-AMP Bac7(1-35) is active against some multidrug-resistant cystic fibrosis isolates of By confocal microscopy and cytometric analyses, we investigated the mechanism of killing against strain PAO1 and three selected isolates, and we observed that the peptide inactivated the target cells by disrupting their cellular membranes.

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The Zn-dependent membrane-located protease YvjB has previously been shown to serve as a target receptor for LsbB, a class II leaderless lactococcal bacteriocin. Although yvjB is highly conserved in the genus Lactococcus, the bacteriocin appears to be active only against the subspecies L. lactis subsp.

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Sponges harbor a remarkable diversity of microbial symbionts in which signal molecules can accumulate and enable cell-cell communication, such as quorum sensing (QS). Bacteria capable of QS were isolated from marine sponges; however, an extremely small fraction of the sponge microbiome is amenable to cultivation. We took advantage of community genome assembly and binning to investigate the uncultured majority of sponge symbionts.

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A sub-group of LuxR family of proteins that plays important roles in quorum sensing, a process of cell-cell communication, is widespread in proteobacteria. These proteins have a typical modular structure consisting of N-ter autoinducer binding and C-ter helix-turn-helix (HTH) DNA binding domains. The autoinducer binding domain recognizes signaling molecules which are most often N-acyl homoserine lactones (AHLs) but could also be other novel and yet unidentified molecules.

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Pseudomonas mediterranea strain CFBP 5447(T) is a phytopathogenic bacterium isolated from tomato plants affected by pith necrosis disease. Moreover, its ability to produce medium-chain-length polyhydroxyalkanoates (mcl-PHAs) in culture from different carbon sources and valuable microbial products, such as cyclic lipopeptides, has been well documented. Here, we report the first draft genome sequence of this species.

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Erwinia toletana was first reported in 2004 as a bacterial species isolated from olive knots caused by the plant bacterium Pseudomonas savastanoi pv. savastanoi. Recent studies have shown that the presence of this bacterium in the olive knot environment increases the virulence of the disease, indicating possible interspecies interactions with P.

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Xanthomonas oryzae pv. oryzae (Xoo) is the second most important rice pathogen, causing a disease called bacterial leaf blight. Xoo colonizes and infects the vascular tissue resulting in tissue necrosis and wilting causing significant yield losses worldwide.

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Pseudomonas fuscovaginae was first reported as a pathogen of rice causing sheath rot in plants grown at high altitudes. P. fuscovaginae is now considered a broad-host-range plant pathogen causing disease in several economically important plants.

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Pathogenic bacteria interact not only with the host organism but most probably also with the resident microbial flora. In the knot disease of the olive tree (Olea europaea), the causative agent is the bacterium Pseudomonas savastanoi pv. savastanoi (Psv).

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The genus Burkholderia includes over 60 species isolated from a wide range of environmental niches and can be tentatively divided into two major species clusters. The first cluster includes pathogens such as Burkholderia glumae, B. pseudomallei, and B.

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Chorismate mutase (CM) is a key enzyme in the shikimate pathway which is responsible for the synthesis of aromatic amino acids. There are two classes of CMs, AroQ and AroH, and several pathogenic bacteria have been reported to possess a subgroup of CMs designated AroQ(gamma). These CMs are usually exported to the periplasm or outside the cell; in a few cases, they have been reported to be involved in virulence and their precise role is currently unknown.

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Burkholderia glumae is an emerging seed-borne rice pathogen in many areas around the world. Previous studies have demonstrated that B. glumae produces two major virulence factors: the phytotoxin toxoflavin and a secreted lipase.

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Eight luxI-family gene promoters (luxI, cviI, ahlI, rhlI, cepI, phzI, traI and ppuI) were cloned in tandem, upstream a promoterless lacZ gene in a promoter probe vector yielding pMULTIAHLPROM. This unique construct is useful in determining whether a bacterial strain not producing N-acyl homoserine lactone signal molecules (AHLs) possesses orphan LuxR type proteins able to respond to AHLs and activate transcription from quorum sensing target genes. Using pMULTIAHLPROM, it was demonstrated that Enterobacter aerogenes possibly contains a LuxR-family orphan able to activate luxI-family promoters independently from AHLs.

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Article Synopsis
  • Burkholderia glumae is a rice pathogen that can also affect humans, particularly those with certain health conditions.
  • The first clinical isolate of B. glumae, strain AU6208, retains its ability to be highly pathogenic to rice through AHL quorum sensing, which influences the production of virulence factors like LipA lipase and the toxin toxoflavin.
  • The study demonstrates that a mutation in the tofR regulator can enhance the pathogenicity of B. glumae, marking a significant finding in understanding its role as a rice pathogen.
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Endo-polygalacturonases (endoPGs) belong to the glycoside hydrolase family 28 and hydrolyze the alpha-1,4 glycosidic bond present in the smooth regions of pectins. Pectic substances are among the principal macromolecular components of the primary plant cell walls and are subjected to enzymatic degradation not only in the course of important physiological processes such as plant senescence and ripening, but also during infection events by plant pathogens. Here we report, for the first time, the isolation and the purification of an endoPG (PehA) from the supernatant of the plant pathogen Burkholderia cepacia strain ATCC 25416.

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Gram-negative bacteria most often use N-acyl homoserine lactones (AHLs) as intercellular quorum-sensing signal molecules. In this study, it was demonstrated that rice plants contain AHL mimic molecules that are very sensitive to the highly specific AiiA lactonase enzyme and can activate three different AHL bacterial biosensors, indicating that the compounds have a homoserine lactone structure and could be AHLs. The possible source and biological significance of this finding are discussed.

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