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See detailTandem MS of -new- antibiotics from Bacillus guided by MALDI Mass Spectrometry Imaging
Debois, Delphine ULg; Jourdan, Emmanuel; Cawoy, Hélène ULg et al

Conference (2013, December 05)

Generally, an antibiotic is thought to have a role in antagonism simply because the producing strain is known to exhibit a potential for pathogen growth inhibition. Some genetic approaches such as PCR ... [more ▼]

Generally, an antibiotic is thought to have a role in antagonism simply because the producing strain is known to exhibit a potential for pathogen growth inhibition. Some genetic approaches such as PCR using specific primers or genome mining using known sequence data of close relatives are also used. Nevertheless, none of these methods allows stating for a link between a specific compound and the observed antagonism. Yet MALDI Mass Spectrometry Imaging (MSI) is a powerful tool to decipher the chemical messengers exchanged by two protagonists [1,2,3;]. Tandem mass spectrometry (MS/MS) may be also used, either on extracts [2,3] or directly on the microbial colonies [4]. The presentation will thus be focused on two examples of application of MALDI MSI combined to in situ tandem mass spectrometry. The first presented case will be the antagonism between soilborne strain Paenibacillus polymyxa Pp56 and the fungal phytopathogen Fusarium oxysporum. Using MALDI MSI, we were able to precisely localize each detected antibiotic, allowing discriminating which LI-F lipopeptides (fusaricidin) were really active against the pathogen progression. Besides, the use of in situ MS/MS allowed us to sequence the peptide moiety of several LI-F lipopeptides, showing that some of them are actually a mixture of several forms. The second example concerns the metabolites that are released by Bacillus amyloliquefaciens S499 cells following their inoculation on 7 days old tomato roots. We developed specific bioassays for time-course monitoring by MALDI MSI. First analyses revealed an efficient secretion of surfactin by Bacillus cells after 3 days when colonization as biofilm-structured populations is well established. Even if the composition of antibiotic mixture does not greatly evolve over time, after long incubation periods (32 or 35 days post inoculation), new series of compounds are detected in the tomato root -surrounding medium. Structural analysis based on exact mass measurements and MS/MS experiments, performed directly on the semi-solid agar medium, allowed us to identify these compounds as new variants of surfactins. [1] Barger, S., et al., Anton Leeuw Int J G, 2012, 102, 435-445. [2] Hoefler, B. C., et al,. Natl Acad Sci USA, 2012, 109, 13082-13087. [3] Moree, W. J., et al., Natl Acad Sci USA, 2012, 109, 13811-13816. [4] Debois, D., et al., J Am Soc Mass Spectrom. 2013, 24, 1202-1213 [less ▲]

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See detailCharacterisation of fengycin homologues produced by B. amyloliquefaciens (ET) strain isolated from a salt lake (Eastern Algeria)
Ait Kaki, Asma ULg; Noreddine, K.C.; Kara Ali, M. et al

Poster (2013, November 15)

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See detailLIPID INTERACTION PROPERTIES OF NOVEL RHAMNOLIPIDS
Nasir, Mehmet Nail ULg; Crowet, Jean-Marc ULg; Lins, Laurence ULg et al

Conference (2013, November)

Biosurfactants which are surface active molecules produced by micro-organisms present a wide structural diversity (glycolipids, lipoaminoacids, lipopeptides, polymers,...) and numerous advantages compared ... [more ▼]

Biosurfactants which are surface active molecules produced by micro-organisms present a wide structural diversity (glycolipids, lipoaminoacids, lipopeptides, polymers,...) and numerous advantages compared to their chemically synthesized counterparts. Among glycolipids, rhamnolipids which are secondary metabolites produced mainly by strains of Pseudomonas aeruginosa, have drawn particular attention as they have several interesting biological properties such as antimicrobial, antiphytoviral, zoosporicidal and plant defense elicitor activities [1-3]. It is generally recognized that these activities must be linked to the interaction of these molecules with constituents of biological membranes [4] but the detailed mechanism is far from being fully understood. In our laboratory, new rhamnolipids with various chain lengths and with or without a terminal carboxylic acid function were obtained via the development of a synthesis procedure consisting of two biocatalyzed steps involving naringinase and lipase [5]. The objective of this work was to investigate their interaction with model membranes in relation with their structure in order to give insight about the mechanism of their biological action. A range of complementary experimental and modelling methods was used to analyze their interaction with membrane models. Results reveal differential interaction with lipids according to the structure of the rhamnolipid. The nature of the lipid is also a key parameter for the ınteractions. [less ▲]

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See detailINFLUENCE OF THE NATURE OF SUGAR RESIDUES ON THE INTERACTIONS OF SYMETRIC SUGAR- BASED BOLAFORMS WITH MODEL MEMBRANES
Nasir, Mehmet Nail ULg; Crowet, Jean-Marc ULg; Lins, Laurence ULg et al

Poster (2013, November)

Glycolipid surfactants constitute a class of natural compound having interest in biological field such as antifungal, antiviral and plant-elicitor and for pharmaceutical formulation as well as for food ... [more ▼]

Glycolipid surfactants constitute a class of natural compound having interest in biological field such as antifungal, antiviral and plant-elicitor and for pharmaceutical formulation as well as for food and cosmetic field. Their action may be modulated through their interactions with plasma membranes of target cells and more particularly by their interactions with membrane lipid molecules. Among glycolipid surfactants, bolaforms constitute an important class; they are composed of two hydrophilic heads connected by a hydrophobic carbon segment.Their interest lies mainly in the development of the efficient and low cost lipid-based drug delivery systems. In this context, our work was focused on two sugar-based bolaforms. They are composed by two identical hydrophilic head constituted by xylose ( BolaX) or rhamnose ( BolaR), connected by an ether link to a hydrocarbon segment with an insaturation. The interactions of  BolaX and BolaR with model phopsholipid and phospholipid/sterol model membranes (Langmuir monolayers at the air-water interface and multilamellar vesicles) were investigated with biophysical and in silico approaches. Our results indicate that both bolaforms interact with model membranes at the level of hydrocarbon chain and, at the phosphate and the carbonyl group of phospholipids. The presence of sterol in the system has an influence on insertion of bolaforms and change slightly the nature of the interactions. The insertion of BolaR within a phospholipid bilayer was deeper than that of  BolaX and its interactions with phospholipids were energetically more favorable, suggesting an important role of the nature of sugar residue. [less ▲]

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See detailReprogramming of fatty acid and oxylipin synthesis in rhizobacteria-induced systemic resistance in tomato
Mariutto, Martin; Fauconnier, Marie-Laure ULg; Ongena, Marc ULg et al

in Plant Molecular Biology (2013), 84(4-5), 455-476

The rhizobacterium Pseudomonas putida BTP1 stimulates induced systemic resistance (ISR) in tomato. A previous work showed that the resistance is associated in leaves with the induction of the first enzyme ... [more ▼]

The rhizobacterium Pseudomonas putida BTP1 stimulates induced systemic resistance (ISR) in tomato. A previous work showed that the resistance is associated in leaves with the induction of the first enzyme of the oxylipin pathway, the lipoxygenase (LOX), leading to a faster accumulation of its product, the free 13-hydroperoxy octadecatrienoic acid (13-HPOT), 2 days after Botrytis cinerea inoculation. In the present study, we further investigated the stimulation of the oxylipin pathway: metabolites and enzymes of the pathway were analyzed to understand the fate of the 13-HPOT in ISR. Actually the stimulation began upstream the LOX: free linolenic acid accumulated faster in P. putida BTP1-treated plants than in control. Downstream, the LOX products 13-fatty acid hydroperoxides esterified to galactolipids and phospholipids were more abundant in bacterized plants than in control before infection. These metabolites could constitute a pool that will be used after pathogen attack to produce free fungitoxic metabolites through the action of phospholipase A2, which is enhanced in bacterized plants upon infection. Enzymatic branches which can use as substrate the fatty acid hydroperoxides were differentially regulated in bacterized plants in comparison to control plants, so as to lead to the accumulation of the most fungitoxic compounds against B. cinerea. Our study, which is the first to demonstrate the accumulation of an esterified defense metabolite during rhizobacteria-mediated induced systemic resistance, showed that the oxylipin pathway is differentially regulated. It suggests that this allows the plant to prepare to a future infection, and to respond faster and in a more effective way to B. cinerea invasion. [less ▲]

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See detailMALDI-FTICR MS Imaging as a Powerful Tool to Identify Paenibacillus Antibiotics Involved in the Inhibition of Plant Pathogens
Debois, Delphine ULg; Ongena, Marc ULg; Cawoy, Hélène ULg et al

in Journal of the American Society for Mass Spectrometry (2013), 24(8), 1202-1213

Nowadays, microorganisms are more and more often used as biocontrol agents for crop protection against diseases. Among them, bacteria of Bacillus and Paenibacillus genders are already used as commercial ... [more ▼]

Nowadays, microorganisms are more and more often used as biocontrol agents for crop protection against diseases. Among them, bacteria of Bacillus and Paenibacillus genders are already used as commercial biocontrol agents. Their mode of action is supposed to be related to their production of antibiotics, such as cyclic lipopeptides, which exhibit great antimicrobial activities. We chose to work with a Paenibacillus polymyxa strain (Pp56) very resistant to various microorganisms. The bacteria were grown simultaneously with Fusarium oxysporum and we applied matrix-assisted laser desorption/ionization-Fourier transform ion cyclotron resonance (MALDI-FTICR) mass spectrometry to identify the antibiotics compounds present in the fungus growth inhibition area. We, therefore, identified fusaricidins A, B, and C and numerous members of the LI-F antibiotics family. MALDIFTICR mass spectrometry imaging was then used to follow the diffusion of lipopeptides involved in the inhibitory activity over time. We analyzed the molecular content of the inhibitory area at different Pp56 and Fusarium incubation durations and concluded that some lipopeptides such as fusaricidin B and a mixture of LI-F05b/06b/08a were mainly involved in the defense mechanism of Pp56. Our study confirms that MALDI imaging may be a powerful tool to quickly determine which molecular species is involved in an antagonism with another microorganism, avoiding time-consuming steps of extraction, purification, and activity tests, which are still commonly used in microbiology. [less ▲]

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See detailEliciteurs dérivés de rhamnolipides : synthèses, modélisations et activités biologiques
Mayon, Patrick; Ait Barka, Essaid; Baillieul, Fabienne et al

Poster (2013, July 04)

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See detailAntimicrobial Activity of Bacillus amyloliquefaciens ANT1 Toward Pathogenic Bacteria and Mold: Effects on Biofilm Formation
Arguelles Arias, Anthony ULg; Nastro, Rosa Anna; Ongena, Marc ULg et al

in Probiotics and Antimicrobial Proteins (2013)

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See detailDevelopment of formulated elicitors to control bioagressors of wheat
Le Mire, Géraldine ULg; Deleu, Magali ULg; Ongena, Marc ULg et al

Scientific conference (2013, July)

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See detailDistribution and identification of molecular interactions between tomato roots and bacterial biofilms
Debois, Delphine ULg; Jourdan, Emmanuel; Smargiasso, Nicolas ULg et al

Poster (2013, June 12)

Some non-pathogenic microorganisms evolving in the root micro-environment can trigger a positive effect on plant, increasing host defense against disease or/and directly inhibiting growth of pathogen in ... [more ▼]

Some non-pathogenic microorganisms evolving in the root micro-environment can trigger a positive effect on plant, increasing host defense against disease or/and directly inhibiting growth of pathogen in soil (1). To initiate both phenomena leading to biocontrol activity, microorganisms use plant exudates to grow on roots and to produce in-situ active compounds. In Bacilli, cyclic lipopeptides of the surfactin, iturin and fengycin families represent important antibiotics involved in biocontrol (2). Recent studies in microbiology allowed a better understanding of plant microorganism interactions but few has been done at the molecular level. In this study, MALDI MS imaging has been used to study the nature of the secreted lipopeptide molecules, their relative quantity and their distribution in the root’s environment.Disinfected tomato seeds were first germinated at 28°C in sterile conditions for germination. Seedlings were then placed in Petri dish on ITO glass slide recovered with a thin layer of plant nutritive solution containing 1,75% of agar and treated with freshly-grown cells of Bacillus amyloliquefaciens S499. Petri dishes were incubated at 28°C with a 16h photoperiod. Different growth / incubation durations were studied: 10/3; 13/7; 21/14 and 39/32. For MALDI imaging experiments, the ITO slide was removed from the agar and dried in a dessiccator under vacuum. (HCCA, 5mg/mL in ACN/0.2% TFA 70:30) was used as matrix. UltraFlex II TOF/TOF and Solarix FT-ICR mass spectrometers were used to record molecular cartographies and perform MS/MS experiments for structural analysis purposes. The average mass spectra recorded around the tomato root (2-3 mm on both sides of the root) showed that lipopeptides were major compounds detected on the agar. The relative intensity of lipopeptides families varied with respect to the age of the root/biofilm system. In the 10/3 system, 3 homologues of surfactins were essentially detected (C13, C14 and C15), with very few iturins and fengycins. Their localizations were identical, whatever the considered homologue. Then the production of iturin and fengycin families increases in older systems (13/7 and 21/14) and a novel homologue of surfactin is detected (C12). Some variations in localizations within families may be observed (around the root or at the close vicinity of it in function of the considered homologue or alkali adduct). Then for the oldest system we studied, iturins and fengycins are not detected anymore and the localization of surfactins is less precise. In the 39/32 system, we also detected unknown compounds at 986.6, 1000.6, 1014.7 and 1028.7 m/z. The mass range of these compounds allied to the mass difference between two consecutive ion peaks let us think that these unknown compounds could be a new lipopeptide family. Tandem mass spectrometry experiments, performed on the dried culture medium, allowed to partially sequence these new lipopeptides. MS/MS results allied to exact mass measurements and isotopic pattern simulation give good confidence in the chemical structure we suggest. Nevertheless, to fully identify these new variants of surfactin, micro-extractions followed by (LC)-nano-ESI-MS/MS using a LESA module are in progress. MALDI Mass Spectrometry Imaging becomes a tool to decipher inter-species molecular communication. [less ▲]

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See detailFirst evidence of a Lysobacter member as a biological control agent of Plasmopara viticola
Puopolo, G.; Jourdan, E.; Ongena, Marc ULg et al

in Bulletin OILB/SROP = IOBC/WPRS Bulletin (2013), 86

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See detailInsights on the role played by temperature on the biocontrol agent Bacillus amyloliquefaciens strain S499
Puopolo, Gerardo; Jourdan, E.; Ongena, Marc ULg et al

in Bulletin OILB/SROP = IOBC/WPRS Bulletin (2013), 86

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See detailBiocontrol and Plant Growth Promotion Characterization of Bacillus Species Isolated from Calendula officinalis Rhizosphere
Ait Kaki, A.; Kacem Chaouche, N.; Dehimat, L. et al

in Indian Journal of Microbiology (2013), 53(4), 447-452

The phenotypic and genotypic diversity of the plant growth promoting Bacillus genus have been widely investigated in the rhizosphere of various agricultural crops. However, to our knowledge this is the ... [more ▼]

The phenotypic and genotypic diversity of the plant growth promoting Bacillus genus have been widely investigated in the rhizosphere of various agricultural crops. However, to our knowledge this is the first report on the Bacillus species isolated from the rhizosphere of Calendula officinalis. 15 % of the isolated bacteria were screened for their important antifungal activity against Fusarium oxysporum, Botrytis cinerea, Aspergillus niger, Cladosporium cucumerinium and Alternaria alternata. The bacteria identification based on 16S r-RNA and gyrase-A genes analysis, revealed strains closely related to Bacillus amyloliquefaciens, B. velezensis, B. subtilis sub sp spizezenii and Paenibacillus polymyxa species. The electro-spray mass spectrometry coupled to liquid chromatography (ESI-LC MS) analysis showed that most of the Bacillus isolates produced the three lipopeptides families. However, the P. polymyxa (18SRTS) didn't produce any type of lipopeptides. All the tested Bacillus isolates produced cellulase but the protease activity was observed only in the B. amyloliquefaciens species (9SRTS). The Salkowsky colorimetric test showed that the screened bacteria synthesized 6-52 μg/ml of indole 3 acetic acid. These bacteria produced siderophores with more than 10 mm wide orange zones on chromazurol S. The greenhouse experiment using a naturally infested soil with Sclerotonia sclerotiorum showed that the B. amyloliquefaciens (9SRTS) had no significant (P > 0.05) effect on the pre-germination of the chickpea seeds. However, it increased the size of the chickpea plants and reduced the stem rot disease (P < 0.05).These results suggested that the Bacillus strains isolated in this work may be further used as bioinoculants to improve the production of C. officinalis and other crop systems. © 2013 Association of Microbiologists of India. [less ▲]

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See detailAntimicrobial Activity of Bacillus amyloliquefaciens ANT1 Toward Pathogenic Bacteria and Mold: Effects on Biofilm Formation
Nastro, R. A.; Arguelles-Arias, A.; Ongena, Marc ULg et al

in Probiotics and Antimicrobial Proteins (2013), 5

The intensive use and misuse of antibiotics over the last decades have generated a strong selective pressure for the emergence of multi-resistant strains and nosocomial infections. Biofilm has been ... [more ▼]

The intensive use and misuse of antibiotics over the last decades have generated a strong selective pressure for the emergence of multi-resistant strains and nosocomial infections. Biofilm has been demonstrated as a key parameter in spreading infections, especially in hospitals and healthcare units. Therefore, the development of novel anti-biofilm drugs is actually of the upmost importance. Here, the antimicrobial and antibiofilm activities toward pathogenic microorganisms of a set of non-ribosomal synthesized peptides and polyketides isolated from Bacillus amyloliquefaciens ANT1 culture supernatant are presented. © 2013 Springer Science+Business Media New York. [less ▲]

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See detailSystemic resistance induced by Bacillus lipopeptides in Beta vulgaris reduces infection by the rhizomania disease vector Polymyxa betae
Desoignies, N.; Schramme, F.; Ongena, Marc ULg et al

in Molecular Plant Pathology (2013), 14

The control of rhizomania, one of the most important diseases of sugar beet caused by the Beet necrotic yellow vein virus, remains limited to varietal resistance. In this study, we investigated the ... [more ▼]

The control of rhizomania, one of the most important diseases of sugar beet caused by the Beet necrotic yellow vein virus, remains limited to varietal resistance. In this study, we investigated the putative action of Bacillus amylolequifaciens lipopeptides in achieving rhizomania biocontrol through the control of the virus vector Polymyxa betae. Some lipopeptides that are produced by bacteria, especially by plant growth-promoting rhizobacteria, have been found to induce systemic resistance in plants. We tested the impact of the elicitation of systemic resistance in sugar beet through lipopeptides on infection by P. betae. Lipopeptides were shown to effectively induce systemic resistance in both the roots and leaves of sugar beet, resulting in a significant reduction in P. betae infection. This article provides the first evidence that induced systemic resistance can reduce infection of sugar beet by P. betae. © 2012 BSPP AND BLACKWELL PUBLISHING LTD. [less ▲]

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See detailEffect of processing conditions on phenolic compounds and antioxidant properties of date syrup
Abbès, F.; Kchaou, W.; Blecker, Christophe ULg et al

in Industrial Crops & Products (2013), 44

Commercial hydrolytic enzymes (pectinase and cellulase) were investigated for their influence on phenolics and antioxidant activities of date syrup. Content of total phenolics, flavonoids and carotenoids ... [more ▼]

Commercial hydrolytic enzymes (pectinase and cellulase) were investigated for their influence on phenolics and antioxidant activities of date syrup. Content of total phenolics, flavonoids and carotenoids contents were determined spectrophotometrically. Polyphenols composition was examined using HPLC. Seven phenolic compounds (catechin, vanillic acid, caffeic acid, syringic acid, p-coumaric acid, ferulic acid and sinapic acid) were detected in all date syrup extracts. p-Coumaric acid was the major compound of all date syrup extracts, representing 49.223-63.397%. The antioxidant activity of date syrup was evaluated by various antioxidant assays, including total antioxidant, DPPH scavenging test, FRAP, hydrogen peroxide scavenging activity and metal chelating activity.Results showed that the date syrup prepared after extraction with pectinase and cellulase mixture gave the lowest phenolic and flavonoid contents. For same variety, date syrup prepared after extraction with pectinase and cellulase mixture gave the highest carotenoids amounts. The antioxidant activity, determined by several methods, was significantly affected by the extraction method as well as date varieties. In fact, the date syrup prepared after extraction with pectinase and cellulase mixture gave the lowest antioxidant activity. A good correlation between the antioxidant activity and total phenolic content and flavonoid was observed. The discovery of our research is very important to scientists as well as to the fruit-processing industry to produce juice and syrup with high antioxidant activity. © 2012 Elsevier B.V. [less ▲]

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See detailCharacterization of amylolysin, a novel lantibiotic from Bacillus amyloliquefaciens GA1
Arias, A. A.; Ongena, Marc ULg; Devreese, B. et al

in PLoS ONE (2013), 8(12),

Background: Lantibiotics are heat-stable peptides characterized by the presence of thioether amino acid lanthionine and methyllanthionine. They are capable to inhibit the growth of Gram-positive bacteria ... [more ▼]

Background: Lantibiotics are heat-stable peptides characterized by the presence of thioether amino acid lanthionine and methyllanthionine. They are capable to inhibit the growth of Gram-positive bacteria, including Listeria monocytogenes, Staphylococcus aureus or Bacillus cereus, the causative agents of food-borne diseases or nosocomial infections. Lantibiotic biosynthetic machinery is encoded by gene cluster composed by a structural gene that codes for a pre-lantibiotic peptide and other genes involved in pre-lantibiotic modifications, regulation, export and immunity. Methodology/Findings: Bacillus amyloliquefaciens GA1 was found to produce an antimicrobial peptide, named amylolysin, active on an array of Gram-positive bacteria, including methicillin resistant S. aureus. Genome characterization led to the identification of a putative lantibiotic gene cluster that comprises a structural gene (amlA) and genes involved in modification (amlM), transport (amlT), regulation (amlKR) and immunity (amlFE). Disruption of amlA led to loss of biological activity, confirming thus that the identified gene cluster is related to amylolysin synthesis. MALDI-TOF and LC-MS analysis on purified amylolysin demonstrated that this latter corresponds to a novel lantibiotic not described to date. The ability of amylolysin to interact in vitro with the lipid II, the carrier of peptidoglycan monomers across the cytoplasmic membrane and the presence of a unique modification gene suggest that the identified peptide belongs to the group B lantibiotic. Amylolysin immunity seems to be driven by only two AmlF and AmlE proteins, which is uncommon within the Bacillus genus. Conclusion/Significance: Apart from mersacidin produced by Bacillus amyloliquefaciens strains Y2 and HIL Y-85,544728, reports on the synthesis of type B-lantibiotic in this species are scarce. This study reports on a genetic and structural characterization of another representative of the type B lantibiotic in B. amyloliquefaciens. Copyright: © 2013 Arguelles Arias et al. [less ▲]

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