Material influence on biocontamination level and adhering cell physiology

In most environments, association with a surface in a structure known as a biofilm is the prevailing microbial lifestyle. Several factors may influence the biofilm formation e.g. nutrients, temperature, flow velocity, initial microflora and the nature of materials. Considering the biocontamination mechanism described in four steps, the initial adhesion is a key element in the biocontamination phenomenon and the substratum is of major concern in controlling bacterial adhesion. Stainless steel is well used in numerous markets because of its high cleanability and corrosion resistance properties. However, other materials are put forward by focusing on properties which differentiate them from those of stainless steel. Thereby, to select the material best suited to the problem, there should have data on their aptitude for biocontamination as well as adhesion impact on cell physiology. For all materials, the ratio of dead adhering cells is lower than 55%. The results obtained show that cell injury is not higher on material known to be bactericidal than on other ones.Dans la plupart des environnements, les microorganismes vivent pr ́ ef ́ erentiellement au sein de biofilms. De nombreux facteurs influencent leur formation i.e. les nutriments, la temp ́ erature, le r ́ egime du fluide environnent, la microflore et les mat ́ eriaux. Dans le m ́ ecanisme de biocontamination, d ́ ecrit en quatre ́ etapes successives, l’adh ́ esion initiale est un ́ el ́ ement cl ́ e de la bioadh ́ esion et les mat ́ eriaux un ́ el ́ ement majeur pour son contr ˆ ole. L’acier inoxydable est tr ` es utilis ́ e dans de nombreux secteurs d’activit ́ e pour sa bonne nettoyabilit ́ e et son excellente r ́ esistance ` a la corrosion. Pour se diff ́ erencier, certains mat ́ eriaux mettent en avant d’autres propri ́ et ́ es.Ainsi,las ́ election du mat ́ eriau le mieux adapt ́ e ` a un probl ` eme donn ́ en ́ ecessite de connaitre son aptitude ` a la biocontamination ainsi que son impact sur la physiologie des microorganismes. Pour tous les mat ́ eriaux test ́ es, la mortalit ́ e des bact ́ eries adh ́ erentes est inf ́ erieure ` a55%.Lesr ́ esultats obtenus ont montr ́ e qu’un mat ́ eriau dit antimicrobien n’induit pas plus de cellules endommag ́ ees comparativement aux autres mat ́ eriaux

Material influence on biocontamination level and adhering cell physiology Influence des matériaux sur le niveau de biocontamination et la physiologie des cellules adhérentes

Dans la plupart des environnements, les microorganismes vivent préférentiellement au sein de biofilms. De nombreux facteurs influencent leur formation i.e. les nutriments, la température, le régime du fluide environnent, la microflore et les matériaux. Dans le mécanisme de biocontamination, décrit en quatre étapes successives, l'adhésion initiale est un élément clé de la bioadhésion et les matériaux un élément majeur pour son contrôle. L'acier inoxydable est très utilisé dans de nombreux secteurs d'activité pour sa bonne nettoyabilité et son excellente résistance à la corrosion. Pour se différencier, certains matériaux mettent en avant d'autres propriétés. Ainsi, la sélection du matériau le mieux adapté à un problème donné nécessite de connaitre son aptitude à la biocontamination ainsi que son impact sur la physiologie des microorganismes. Pour tous les matériaux testés, la mortalité des bactéries adhérentes est inférieure à 55 %. Les résultats obtenus ont montré qu'un matériau dit antimicrobien n'induit pas plus de cellules endommagées comparativement aux autres matériaux. In most environments, association with a surface in a structure known as a biofilm is the prevailing microbial lifestyle. Several factors may influence the biofilm formation e.g. nutrients, temperature, flow velocity, initial microflora and the nature of materials. Considering the biocontamination mechanism described in four steps, the initial adhesion is a key element in the biocontamination phenomenon and the substratum is of major concern in controlling bacterial adhesion. Stainless steel is well used in numerous markets because of its high cleanability and corrosion resistance properties. However, other materials are put forward by focusing on properties which differentiate them from those of stainless steel. Thereby, to select the material best suited to the problem, there should have data on their aptitude for biocontamination as well as adhesion impact on cell physiology. For all materials, the ratio of dead adhering cells is lower than 55%. The results obtained show that cell injury is not higher on material known to be bactericidal than on other ones

Determination of the van der Waals, electron donor and electron acceptor surface tension components of static Gram-positive microbial biofilms

A large number of studies have shown the influence of the physico-chemical properties of a surface on microbial adhesion phenomenon. In this study, we considered that the presence of a bacterial biofilm may be regarded as a "conditioning film" that may modify the physico-chemical characteristics of the support, and thus the adhesion capability of planktonic micro-organisms coming into contact with this substratum. In this context, we adapted a protocol for biofilm formation that allows, under our experimental conditions, contact angle measurements, the reference method to determine the energetic surface properties of a substratum. This made it possible to determine the van der Waals, electron acceptor and electron donor properties of static biofilms grown at 25 degrees C on stainless-steel slides with six Gram-positive bacteria isolated in dairy plants. A variance analysis indicated significant effects (P<0.05) of the bacterial strains and of the physiological state of the micro-organisms (planktonic or sessile) on the contact angles. To link the energetic properties of the six biofilms with direct adhesion experiments, we measured the affinity of fluorescent carboxylate-modified polystyrene beads for the different biofilm surfaces. The results correlated best with the electron-acceptor components of the biofilm surface energies, stressing the importance of Lewis acid-base interactions in adhesion mechanisms

Exploring complex transitions between polymorphs on a small scale by coupling AFM, FTIR and DSC: the case of Irganox 1076 (R) antioxidant

This study illustrates the significant interest of using atomic force microscopy (AFM) in force curve imaging mode for discovering and studying not easily detectable solid/solid transitions between polymorphs: we show that AFM in this imaging mode is a powerful means for studying in situ these transitions as they can be (i) detected in a very early step because of the high spatial resolution (at nanometer scale) of AFM and (ii) be distinguished from melting/recrystallization processes that can occur in the same temperature range. This was illustrated with the case of Irganox 1076 (R). This compound is a phenolic antioxidant currently used in standard polymers; it can bloom on the surface of polymer-based medical devices and its polymorphism might affect the device surface state and thus the biocompatibility. In a previous paper, the polymorphism of this compound was studied: four forms were characterized at a macroscopic level and one of them (form III) was identified on the surface of a polyurethane catheter. However, it was difficult to characterize the transitions between the different forms with only classical tools (DSC, FTIR and SAXS). In the present study, to evidence these transitions, we use AFM measurements coupled with a heating stage and we correlate them to ATR-FTIR measurements and to DSC analysis. This new study put into evidence a solid-solid transition between form III and II

Les flagelles d’Escherichia coli entérohémorragiques dans l’adhésion et la colonisation des surfaces

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Combined Effects of Long-Living Chemical Species during Microbial Inactivation Using Atmospheric Plasma-Treated Water▿

Electrical discharges in humid air at atmospheric pressure (nonthermal quenched plasma) generate long-lived chemical species in water that are efficient for microbial decontamination. The major role of nitrites was evidenced together with a synergistic effect of nitrates and H2O2 and matching acidification. Other possible active compounds are considered, e.g., peroxynitrous acid

Escherichia coli Resistance to Nonbiocidal Antibiofilm Polysaccharides Is Rare and Mediated by Multiple Mutations Leading to Surface Physicochemical Modifications

Antivirulence strategies targeting bacterial behavior, such as adhesion and biofilm formation, are expected to exert low selective pressure and have been proposed as alternatives to biocidal antibiotic treatments to avoid the rapid occurrence of bacterial resistance. Here, we tested this hypothesis using group 2 capsule polysaccharide (G2cps), a polysaccharidic molecule previously shown to impair bacterium-surface interactions, and we investigated the nature of bacterial resistance to a nonbiocidal antibiofilm strategy. We screened an Escherichia coli mutant library for an increased ability to form biofilm in the presence of G2cps, and we identified several mutants displaying partial but not total resistance to this antibiofilm polysaccharide. Our genetic analysis showed that partial resistance to G2cps results from multiple unrelated mutations leading to modifications in surface physicochemical properties that counteract the changes in ionic charge and Lewis base properties induced by G2cps. Moreover, some of the identified mutants harboring improved biofilm formation in the presence of G2cps were also partially resistant to other antibiofilm molecules. This study therefore shows that alterations of bacterial surface properties mediate only partial resistance to G2cps. It also experimentally validates the potential value of nonbiocidal antibiofilm strategies, since full resistance to antibiofilm compounds is rare and potentially unlikely to arise in clinical settings

Adhesion on polyethylene glycol and quaternary ammonium salt-grafted silicon surfaces: Influence of physicochemical properties

The aim of this work was to develop a new generation of antimicrobial materials. In order to restrict surface contamination by micro-organisms, the approach developed consisted in modifying the surface properties of a silicone wafer by grafting antimicrobial compounds such as quaternary ammonium salts (QAS) and polyethylene glycol (PEG). Under this approach, the grafted compound was endowed with a functionalised extremity which allowed it to react with the silicone wafer in order to form a covalent bond. The first part of this paper describes the synthesis of QAS and PEG molecules, and then the physicochemical characteristics of the modified silicon surfaces were determined. The second part concerned determination of the surface properties of the wafers and polystyrene beads used for adhesion tests. In line with the extended DLVO theory, it was thus possible to understand the mechanisms involved in the adhesion of polystyrene beads to the surface of QAS and PEG-modified silicon wafers