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The aim of this study was to evaluate the effect of chemical compounds found in different water types on the physico-chemical properties of bacteria and the adhesion of two strains (Pseudomonas aeruginosa and Escherichia coli) to glass, PVC and stainless steel. P. aeruginosa and E. coli were exposed to two sterile water types (distilled water and tap water) for 3 h. Contact angle measurements were used to assess the surface properties of both strains and coupons of different materials. The hydrophobicity and the electron donor properties of the bacterial strains seems to increase when exposed to sterile tap water compared to distilled water, while the electron acceptor property is largely unchanged. The adhesion tests were carried out in a water circuit creating turbulence. The number of adhered cells was determined after their detachment from the coupons using an ultrasonic bath for 2 min. The findings showed that the type of water affects the adhesion of both strains, which is stronger in tap water than distilled water. A correlation test to determine the surface property that governs adhesion in these conditions, suggested that the adhesion is mainly governed by hydrophobicity.

To improve the start-up speed and efficiency of bioreactors, biofilm technology is sometimes used. This technology uses various types of materials to facilitate the adhesion of microorganisms. In this study, the surface characteristics of inert substrates and substrates after olive oil-mill wastewater (OMWW) conditioning film were evaluated to understand the impact of OMWW on adhesion as well as the most suitable material to optimize bacterial adhesion. Three common substrates made of different polymers were tested for bacterial adhesion before and after treatment with OMWW: PP (polypropylene), PET (Polyethylene terephthalate), and PVC (polyvinyl chloride). The surfaces’ physicochemical characteristics were studied by measuring the contact angle for the studied bacteria strain and the supports, before and after treatment with OMWW. Results of initial adhesion tests for untreated and treated supports showed differences in how bacterial cells adhered to substrates. Before treatment with OMWW, PVC and then PP showed a significant adhesion capacity, double that of PET [PVC: 1.58 × 105 CFU/cm2, PP: 1.48 × 105 CFU/cm2 and PET: 0.72 × 105 CFU/cm2]. After treatment with OMWW, initial bacterial adhesion increased by 106 (from 105 CFU/cm2 for untreated supports to 1011 CFU/cm2 for treated supports), and PET followed by PP demonstrated the highest adhesion capacity, 2 and 1.7 times more than PVC, respectively [PET: 1.39 × 1011 CFU/cm2, PP: 1.15 × 1011 CFU/cm2 and PVC: 0.67 × 1011 CFU/cm2]. OMWW conditioning film affects the physicochemical characteristics of plastic supports, especially the donor electron character, and improves the initial adhesion of bacteria to substrates (105 to 1011 CFU/cm2). Therefore, surfaces’ physicochemical characteristics were important in the initial adhesion of the bacteria onto the support before and after treatment.

Microbial adhesion to surfaces is thought to involve physicochemical interactions between the substrate and microbial cells. Understanding the physicochemical aspects involved in the adhesion phenomenon, as a critical step in biofilm formation, is essential to finding ways to prevent their formation and control biocontamination risks. The aim of this study was to investigate the relation between the adhesion behavior of 12 Escherichia coli strains isolated from food and their surface hydrophobicities using qualitative ( θ w ) and quantitative (ΔGiwi) approaches. The surface physicochemical properties of both bacterial cells and glass material were estimated through contact angle measurements. The adhesive behavior of E. coli strains on a glass surface was assessed. The results showed a good logarithmic relation between the percentage of the adhered cells and their surface hydrophobicity with the quantitative approach ΔGiwi; however, qualitative hydrophobicity ( θ w ) appeared to demonstrate no effect regarding adhesion behavior. This work lays the foundation for future studies and opens an important debate on the mechanisms underlying the adhesion behavior of E. coli strains by using the thermodynamic approach (ΔGiwi) as an important model of hydrophobicity that could explain and predict better bacterial adhesion ability.

The main aim of this work was to determine the most appropriate materials for the installation of a water system according to the characteristics of the water that passes through it. To this end, we conducted an investigation of the effect of two types of water (SDW: sterile distilled water and STW: sterile tap water) on the properties of bacterial surfaces and the theoretical adhesion of two bacteria (Pseudomonas aeruginosa and Escherichia coli) on six plumbing materials. Contact angle measurements were used to determine the surface energies of bacteria and materials. XDLVO theory was used to estimate the interactions between bacteria and plumbing materials. The results showed that water had a clear impact on the electron donor character and the hydrophobicity of the bacterial surfaces. Also, the predictive adhesion showed that all tested materials could be colonized by P. aeruginosa and E. coli ([Formula: see text]

Biofilms are increasingly identified as the source of major industrial, societal and public health problems. The aim of the present paper is to evaluate the risk of contamination of medical surfaces by pathogenic strains. For this purpose, a theoretically estimation of the ability of four pathogenic strains in the medical field: Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa and Salmonella Kentucky to adhere to the surface of four different substrata: Glass, polystyrene (PS), polyethylene (PE) and Stainless Steel 316L (Inox), was studied according to the thermodynamic approach. In order to modify the surface tension of these supports, they were treated with surfactants. The contact angle method was used to estimate the physicochemical properties of the two matrices. According to the results of the total free energy of interactions, the adhesion of these four strains on the treated and untreated glass was not favorable. For the other supports (PE, PS, and inox), the adhesion of the strains was favorable but after the treatment of the supports with surfactants, it appears that the attachment of the cells became unfavorable.

We aimed to investigate the adhesion of Legionella pneumophila serogroup1 and L. pneumophila serogroup2-15 on glass, galvanized steel, stainless steel, copper, Polyvinyl chloride(PVC), Cross-linked polyethylene(PEX-c) and Polypropylene Random Copolymer(PPR). The surface physicochemical properties of both bacterial cells and materials were estimated through contact angle measurements. The roughness and surface topography of the materials were evaluated by Atomic Force Microscopy. The two L. pneumophila serogroups and plumbing materials showed a hydrophobic character, while glass surface was hydrophilic. All strains were adhered to all materials with the exception of copper. The result showed that the adhesion of both L. pneumophila sg1 and sg2-15 was systematically expressed with high intensity on galvanized steel followed by PVC, PEX-c, PPR, stainless steel and the low intensity on glass. The extent of adhesion is in correlation with the surface roughness and acid-bases interactions, while hydrophobicity seems to have no effect in adhesion intensity.

Bacterial proliferation in the form of biofilm fixed on a substrate is the result of a set of physical, chemical and biological processes. Microbial adhesion to a substrate is often considered to be the result of physicochemical interactions between the substrate and the microbial cells. These interactions include electrostatic interactions, Van der Waals interactions and acid-base interactions (electron donor - electron acceptor). The exact role of these physicochemical properties is still poorly documented. The purpose of this work is to provide some clarifications on this subject. The phenomenon of adhesion is often studied on clean surfaces, whereas in reality, it is always conditioned depending on its environment (medical, food or cosmetic). This is why in the present work we treated two different surfaces: glass and polyethylene, with diverse surfactants: nonionic, anionic and cationic. The choice of surfactants was motivated by its wide application in different fields. The physicochemical properties of the two substrata (treated and untreated) were defined using contact angle measurements. Moreover, the adhesive behavior of Staphylococcus aureus, as a bacterial model, on the studied substratum was assessed. The obtained results indicate that the physicochemical parameters of the two supports have changed in a specific way to each surfactant. The non-ionic surfactant turned both the surfaces more hydrophilic. However, the anionic and cationic surfactants have reversed the physicochemical characteristics of the surfaces. The correlation coefficients of the physicochemical properties and the adhesive behavior show that there is an association between the wettability of the two surfaces and the rate of the adherent cells.

The surface energy characteristics of uncoated (clean) and coated stainless steel with UHT milk at various contact time (5 min, 30 min, 1 hours, 3 hours, 6 hours, 24 hours) were determined using contact angle measurement. Whatever the contact time, the clean stainless steel coupons became more hydrophobic and more electron acceptor when they are coated by milk. Inversely, the electron donor character seems to decreasing in this condition. The calculated surface energy component of coated stainless steel was found to vary with contact time. Its hydrophobicity and its electron acceptor were minimal after 3 hours of contact, but its electron donor was minimal after 1 hours of contact. Adhesion experiments of Staphylococcus aureus were carried out on uncoated and coated stainless steels at various contact times. For all contact times, the adhesion results show that milk reduce S. aureus adhesion, and the level of this reduction depend on contact time. This reduction was lower and higher after 1 hours, 5 min and 30 min of contact respectively.

Escherichia coli surface characteristics including hydrophobicity, electrophoretic mobility and surface functional groups' composition were investigated. These characteristics were determined respectively by water contact angle measurements, microelectrophoresis and x-ray photoelectron spectroscopy (XPS). The relation between the physicochemical properties and functional groups' composition was also examined. The electrophoretic mobility at pH 7 appeared to be governed on the cell surface by the (O=C) functional groups. The cell surface's hydrophilicity was associated with high levels of (C-(O.N)) and (OH-(C-O-C)) functional groups, whereas the cell surface's hydrophobicity was associated with (C-(C,H)) functional groups. Características de superfície de Escherichia coli, tais como hidrofobicidade, mobilidade eletroforética e composição dos grupos funcionais de superfície, foram estudadas. Essas características foram determinadas por medidas de angulo de contato com água, microeletroforese e espectroscopia fotoeletrônica de raio-X (XPS), respectivamente. A relação entre as propriedades fisicoquímicas e a composição dos grupos funcionais foi também examinada. Aparentemente, a mobilidade eletroforética em pH 7 é controlada na superfície celular pelos grupos funcionais (O=C). A hidrofilicidade da superfície celular estava associada com altos níveis dos grupos funcionais [C-(O.N)] e [OH-(C-O-C)], enquanto a hidrofobicidade estava associada com os grupos funcionais [C-(C,H)].