Identification et caractérisation des exopolymères de biofilms de bactéries marines

Dans l environnement marin, les surfaces artificielles sont rapidement colonisées par des bactéries qui s organisent en communautés appelées biofilms, s entourant d une matrice de substances polymériques extracellulaires (EPS). La formation d un biofilm est une étape critique du processus nommé biofouling, c est-à-dire l accumulation de micro- et de macro-organismes sur une surface immergée, pouvant conduire à des conséquences néfastes dans le secteur marin. Dans cette étude, il s agit d identifier des souches bactériennes isolées de supports immergés en Mer Méditerranée et de les caractériser phénotypiquement par diverses approches. Leur capacité à former un biofilm in vitro a été évaluée dans différentes conditions avec une attention particulière portée sur leurs capacités à produire une matrice polymérique abondante riche en polysaccharides; l objectif étant d isoler des exopolysaccharides originaux à activité antifouling. Treize souches ont ainsi fait l objet d analyses phylogénétiques et d une caractérisation phénotypique. Sept genres et douze espèces différentes ont été identifiés au sein desquelles deux isolats peuvent être affiliés à une nouvelle espèce, nommée Persicivirga mediterranea. Ce genre n a jamais été décrit en Mer Méditerranée jusqu à présent. L extraction des EPS de chaque souche cultivée en biofilm a permis de déterminer leur composition générale en glucides, protéines, acides nucléiques et lipides. Une souche, Pseudoalteromonas ulvae TC14, se distingue par sa capacité à produire des exopolysaccharides en quantité importante. Il s agit essentiellement de polymères du glucose dont les analyses chromatographiques et spectroscopiques ont révélé la diversité de taille (Mw ~ 1 4000 kDa), de charge (neutre ou anionique) et de fonction associée (lactate ou acétate). Les fractions d EPS enrichies en polysaccharides inhibent la formation de biofilm par d autres souches marines. Ces derniers sont également synthétisés par les bactéries en culture planctonique mais en proportions très différentes.In marine environment, artificial surfaces are promptly colonized by biofilms, which are communities of bacteria surrounded by matrix of extracellular polymeric substances (EPS). Formation of biofilm is a critical step of biofouling development, which corresponds to the accumulation of micro and macro-organisms on immersed surfaces and which can have important negative ramifications in particular in the marine sector. In this study, bacteria isolated from the Mediterranean Sea have been identified and characterized using different phenotypical tools. Their capacity to form a biofilm in vitro has been studied in different conditions, with a particular focus on their ability to produce abundant carbohydrate-rich EPS, the overall objective of the study being the isolation of original antifouling-active exopolysaccharides. Thirteen strains have been phylogenetically and phenotypically characterized. Seven genera and twelve species were identified among which two isolates were affiliated to a new species, named Persicivirga mediterranea. This genus has never been described in the Mediterranean Sea. Extraction of EPS of each strain, grown in biofilm conditions, allowed the determination of their general composition in carbohydrates, proteins, nucleic acids and lipids. One strain, Pseudoalteromonas ulvae TC14, was able to produce large quantities of exopolysaccharides, comprising in majority polymers of glucose whose chromatographic and spectroscopic analyzes revealed a diversity in size (Mw ~ 1-4000 kDa), charge (neutral or anionic) and associated function (acetate or lactate). These polysaccharides inhibited biofilm formed by other marine strains isolated from the Mediterranean Sea. They can also be synthesized by planktonic TC14, but in very different proportions.TOULON-Bibliotheque electronique (830629901) / SudocSudocFranceF

Identification et caractérisation des exopolymères de biofilms de bactéries marines

In marine environment, artificial surfaces are promptly colonized by biofilms, which are communities of bacteria surrounded by matrix of extracellular polymeric substances (EPS). Formation of biofilm is a critical step of biofouling development, which corresponds to the accumulation of micro and macro-organisms on immersed surfaces and which can have important negative ramifications in particular in the marine sector. In this study, bacteria isolated from the Mediterranean Sea have been identified and characterized using different phenotypical tools. Their capacity to form a biofilm in vitro has been studied in different conditions, with a particular focus on their ability to produce abundant carbohydrate-rich EPS, the overall objective of the study being the isolation of original antifouling-active exopolysaccharides. Thirteen strains have been phylogenetically and phenotypically characterized. Seven genera and twelve species were identified among which two isolates were affiliated to a new species, named Persicivirga mediterranea. This genus has never been described in the Mediterranean Sea. Extraction of EPS of each strain, grown in biofilm conditions, allowed the determination of their general composition in carbohydrates, proteins, nucleic acids and lipids. One strain, Pseudoalteromonas ulvae TC14, was able to produce large quantities of exopolysaccharides, comprising in majority polymers of glucose whose chromatographic and spectroscopic analyzes revealed a diversity in size (Mw ~ 1-4000 kDa), charge (neutral or anionic) and associated function (acetate or lactate). These polysaccharides inhibited biofilm formed by other marine strains isolated from the Mediterranean Sea. They can also be synthesized by planktonic TC14, but in very different proportions.Dans l’environnement marin, les surfaces artificielles sont rapidement colonisées par des bactéries qui s’organisent en communautés appelées biofilms, s’entourant d’une matrice de substances polymériques extracellulaires (EPS). La formation d’un biofilm est une étape critique du processus nommé biofouling, c’est-à-dire l’accumulation de micro- et de macro-organismes sur une surface immergée, pouvant conduire à des conséquences néfastes dans le secteur marin. Dans cette étude, il s’agit d’identifier des souches bactériennes isolées de supports immergés en Mer Méditerranée et de les caractériser phénotypiquement par diverses approches. Leur capacité à former un biofilm in vitro a été évaluée dans différentes conditions avec une attention particulière portée sur leurs capacités à produire une matrice polymérique abondante riche en polysaccharides; l’objectif étant d’isoler des exopolysaccharides originaux à activité antifouling. Treize souches ont ainsi fait l’objet d’analyses phylogénétiques et d’une caractérisation phénotypique. Sept genres et douze espèces différentes ont été identifiés au sein desquelles deux isolats peuvent être affiliés à une nouvelle espèce, nommée Persicivirga mediterranea. Ce genre n’a jamais été décrit en Mer Méditerranée jusqu’à présent. L’extraction des EPS de chaque souche cultivée en biofilm a permis de déterminer leur composition générale en glucides, protéines, acides nucléiques et lipides. Une souche, Pseudoalteromonas ulvae TC14, se distingue par sa capacité à produire des exopolysaccharides en quantité importante. Il s’agit essentiellement de polymères du glucose dont les analyses chromatographiques et spectroscopiques ont révélé la diversité de taille (Mw ~ 1–4000 kDa), de charge (neutre ou anionique) et de fonction associée (lactate ou acétate). Les fractions d’EPS enrichies en polysaccharides inhibent la formation de biofilm par d’autres souches marines. Ces derniers sont également synthétisés par les bactéries en culture planctonique mais en proportions très différentes

Identification and characterization of exopolymers from biofilms of marine bacteria

Dans l’environnement marin, les surfaces artificielles sont rapidement colonisées par des bactéries qui s’organisent en communautés appelées biofilms, s’entourant d’une matrice de substances polymériques extracellulaires (EPS). La formation d’un biofilm est une étape critique du processus nommé biofouling, c’est-à-dire l’accumulation de micro- et de macro-organismes sur une surface immergée, pouvant conduire à des conséquences néfastes dans le secteur marin. Dans cette étude, il s’agit d’identifier des souches bactériennes isolées de supports immergés en Mer Méditerranée et de les caractériser phénotypiquement par diverses approches. Leur capacité à former un biofilm in vitro a été évaluée dans différentes conditions avec une attention particulière portée sur leurs capacités à produire une matrice polymérique abondante riche en polysaccharides; l’objectif étant d’isoler des exopolysaccharides originaux à activité antifouling. Treize souches ont ainsi fait l’objet d’analyses phylogénétiques et d’une caractérisation phénotypique. Sept genres et douze espèces différentes ont été identifiés au sein desquelles deux isolats peuvent être affiliés à une nouvelle espèce, nommée Persicivirga mediterranea. Ce genre n’a jamais été décrit en Mer Méditerranée jusqu’à présent. L’extraction des EPS de chaque souche cultivée en biofilm a permis de déterminer leur composition générale en glucides, protéines, acides nucléiques et lipides. Une souche, Pseudoalteromonas ulvae TC14, se distingue par sa capacité à produire des exopolysaccharides en quantité importante. Il s’agit essentiellement de polymères du glucose dont les analyses chromatographiques et spectroscopiques ont révélé la diversité de taille (Mw ~ 1–4000 kDa), de charge (neutre ou anionique) et de fonction associée (lactate ou acétate). Les fractions d’EPS enrichies en polysaccharides inhibent la formation de biofilm par d’autres souches marines. Ces derniers sont également synthétisés par les bactéries en culture planctonique mais en proportions très différentes.In marine environment, artificial surfaces are promptly colonized by biofilms, which are communities of bacteria surrounded by matrix of extracellular polymeric substances (EPS). Formation of biofilm is a critical step of biofouling development, which corresponds to the accumulation of micro and macro-organisms on immersed surfaces and which can have important negative ramifications in particular in the marine sector. In this study, bacteria isolated from the Mediterranean Sea have been identified and characterized using different phenotypical tools. Their capacity to form a biofilm in vitro has been studied in different conditions, with a particular focus on their ability to produce abundant carbohydrate-rich EPS, the overall objective of the study being the isolation of original antifouling-active exopolysaccharides. Thirteen strains have been phylogenetically and phenotypically characterized. Seven genera and twelve species were identified among which two isolates were affiliated to a new species, named Persicivirga mediterranea. This genus has never been described in the Mediterranean Sea. Extraction of EPS of each strain, grown in biofilm conditions, allowed the determination of their general composition in carbohydrates, proteins, nucleic acids and lipids. One strain, Pseudoalteromonas ulvae TC14, was able to produce large quantities of exopolysaccharides, comprising in majority polymers of glucose whose chromatographic and spectroscopic analyzes revealed a diversity in size (Mw ~ 1-4000 kDa), charge (neutral or anionic) and associated function (acetate or lactate). These polysaccharides inhibited biofilm formed by other marine strains isolated from the Mediterranean Sea. They can also be synthesized by planktonic TC14, but in very different proportions

Identification of Bacterial Strains Isolated from the Mediterranean Sea Exhibiting Different Abilities of Biofilm Formation

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Modulation of violacein production and phenotypes associated with biofilm by exogenous quorum sensing N-acylhomoserine lactones in the marine bacterium Pseudoalteromonas ulvae TC14

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Antibiofilm activity in the culture supernatant of a marine Pseudomonas sp. bacterium

International audienceIn the marine environment, most solid surfaces are covered by microbial biofilms, mainly composed of bacteria and diatoms. The negative effects of biofilms on materials and equipment are numerous and pose a major problem for industry and human activities. Since marine micro-organisms are an important source of bioactive metabolites, it is possible that they synthesize natural ecofriendly molecules that inhibit the adhesion of organisms. In this work, the antibiofilm potential of marine bacteria was investigated using Flavobacterium sp. II2003 as a target. This strain is potentially a pioneer strain of bacteria that was previously selected from marine biofilms for its strong biofilm-forming ability. The culture supernatants of 86 marine heterotrophic bacteria were tested for their ability to inhibit Flavobacterium sp. II2003 biofilm formation and the Pseudomonas sp. IV2006 strain was identified as producing a strong antibiofilm activity. The Pseudomonas sp. IV2006 culture supernatant (SNIV2006) inhibited Flavobacterium sp. II2003 adhesion without killing the bacteria or inhibiting its growth. Moreover, SNIV2006 had no effect on the Flavobacterium sp. II2003 cell surface hydrophilic/hydrophobic and general Lewis acid–base characteristics, but modified the surface properties of glass, making it on the whole more hydrophilic and more alkaline and significantly reducing bacterial cell adhesion. The glass-coating molecules produced by Pseudomonas sp. IV2006 were found to probably be polysaccharides, whereas the antibiofilm molecules contained in SNIV2006 and acting during the 2 h adhesion step on glass and polystyrene surfaces would be proteinaceous. Finally, SNIV2006 exhibited a broad spectrum of antibiofilm activity on other marine bacteria such as Flavobacterium species that are pathogenic for fish, and human pathogens in both the medical environment, such as Staphylococcus aureus and Pseudomonas aeruginosa , and in the food industry, such as Yersinia enterocolitica . Thus, a wide range of applications could be envisaged for the SNIV2006 compounds, both in aquaculture and human health

Characterization and anti-biofilm activity of extracellular polymeric substances produced by the marine biofilm-forming bacterium <i>Pseudoalteromonas ulvae</i> strain TC14

<p>This study investigated soluble (Sol-EPS), loosely bound (LB-EPS), and tightly bound extracellular polymeric substances (TB-EPS) harvested from biofilm and planktonic cultures of the marine bacterium <i>Pseudoalteromonas ulvae</i> TC14. The aim of the characterization (colorimetric methods, FTIR, GC-MS, NMR, HPGPC, and AFM analyses) was to identify new anti-biofilm compounds; activity was assessed using the BioFilm Ring Test®. A step-wise separation of EPS was designed, based on differences in water-solubility and acidity. An acidic fraction was isolated from TB-EPS, which strongly inhibited biofilm formation by marine bacterial strains in a concentration-dependent manner. The main constituents of this fraction were characterized as two glucan-like polysaccharides. An active poly(glutamyl-glutamate) fraction was also recovered from TB-EPS. The distribution of these key EPS components in Sol-EPS, LB-EPS, and TB-EPS was distinct and differed quantitatively in biofilm <i>vs</i> planktonic cultures. The anti-biofilm potential of the fractions emphasizes the putative antifouling role of EPS in the environment.</p

Isolation and Characterization of Environmental Bacteria Capable of Extracellular Biosorption of Mercury

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Modulation of violacein production and phenotypes associated with biofilm by exogenous quorum sensing N-acylhomoserine lactones in the marine bacterium Pseudoalteromonas ulvae TC14

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