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In this study, we investigated the potential adhesion of marine bacteria isolated from seawater in the port of Chmaâla, Morocco, to sea-immersed 304 and 316 stainless steels using thermodynamic approach and the Environmental Scanning Electron Microscopy (ESEM). Furthermore, the physicochemical properties including hydrophobicity and electron donor / electron acceptor (Lewis acid-base) of bacterial isolates and both substrates were evaluated using the contact angle measurements. The molecular identification indicated that the isolated strains were Bacillus thuringiensis and Bacillus amyloliquefascience. Results also showed that both bacterial strains’s cells have a hydrophilic character with ΔGiwi values of 29.30 and 24.12 mJ m−2 respectively for Bacillus thuringiensis and Bacillus amyloliquefascience, and are strong electron donating (γ−) and weakly electron accepting (γ+). For substrates surfaces, we found that both sea-immersed stainless steels types were hydrophilic and present strong electron-...

The initial adhesion of microorganisms on a substrate is a significant step for biofilm formation. In this work, the contact angle measurement method was used to investigate the effect of three Myrtus communis extractives on the physicochemical properties of cedar wood surface. Indeed, hydrophobicity, electron donor ( γ − ) electron acceptor ( γ + ) parameters and surface tension components (ΔGiwi) of untreated and treated wood were assessed. The results indicated that all extractives tested decreased the hydrophobic parameter and made the cedar wood surface more donor electron. Moreover, the theoretical prediction and the experimental assay of Thielavia hyalocarpa adhesion on untreated and treated substrates were also investigated. According to the values of total free energy of interaction ( Δ G Tot ) , the adhesion of the fungal strain studied on wood was found favorable. However, the treatments made the adhesion conditions unfavorable. Likewise, environmental scanning electron microscopy (ESEM) showed a decrease in cell adhesion with treatment, indicating the highest anti-adherence activity of methanol fraction. Furthermore, a linear relationship between theoretical prediction and experimentally determined adhesion has been obtained.

Biofilm formation on dental biomaterials is implicated in various oral health problems. Thus the challenge is to prevent the formation of this consortium of microorganisms using a safe approach such as antimicrobial and anti-adhesive natural products. Indeed, in the present study, the effects of an antifungal extract of Bacillus sp., isolated from plant rhizosphere, on the surface physicochemical properties of cobalt and nickel based dental alloys were studied using the contact angle measurements. Furthermore, in order to predict the adhesion of Candida albicans to the treated and untreated dental alloys, the total free energy of adhesion was calculated based on the extended Derjaguin-Landau-Verwey-Overbeek approach. Results showed hydrophobic and weak electron-donor and electron-acceptor characteristics of both untreated dental alloys. After treatment with the antifungal extract, the surface free energy of both dental alloys was influenced significantly, mostly for cobalt based alloy. In fact, treated cobalt based alloy became hydrophilic and predominantly electron donating. Those effects were time-dependent. Consequently, the total free energy of adhesion of C. albicans to this alloy became unfavorable after treatment with the investigated microbial extract. A linear relationship between the electron-donor property and the total free energy of adhesion has been found for both dental alloys. Also, a linear relationship has been found between this latter and the hydrophobicity for the cobalt based alloy. However, the exposure of nickel based alloy to the antifungal extract failed to produce the same effect.

The aim of this study was to investigate the effect of cellulase treatment on wood surface physicochemical characteristics. The cedar wood samples were treated by cellulase for 30 min at different concentrations: 0.2, 0.4, 0.6, 0.8, 1, and 1.2 mg/ml. Then the physicochemical properties (the wetting behavior and interfacial free energy) of the cedar samples surfaces were characterized by the sessile drop technique. The obtained results showed that the untreated cedar wood samples exhibited a hydrophobic character with a high water contact angle (θw = 71.9°) and a negative value of the interfacial free energy (∆Giwi = −59.3 mJ/m2). Thereafter, the wood hydrophobicity decreased continuously until it reached the hydrophilicity qualitatively (at the first concentration of cellulase (0.2 mg/ml)) and quantitatively (at 0.8 mg/ml of cellulase). The cedar wood surface treatment with cellulase also revealed a significant evolution of the acid-base parameters. Moreover, a linear relationship between the degr...

Paper from an ancient library of the cultural city of Fez (Morocco) is exposed to rapid deterioration by variety of microorganisms, especially cellulolytic fungi. For this, ten isolates fungi previously isolated from historical biodeteriorated paper were screened for their ability to produce endoglucanase (CMCase), amylase, polygalacturonase and ligninase enzymes. The CMCase activity of cellulolytic strains was essayed in liquid media at 25°C for 10 days. Influence of temperature and pH were assessed for the production of CMCase by all the fungus isolated from decaying paper. The research findings from the present study demonstrate that all the tested isolates had cellulase, amylase, pectinase and ligninase activities. It was found that Mucor racemosus PF15, Aspergillus niger, and Aspergillus oryzae exhibited the maximum endoglucanase activity in liquid medium (0.256, 0.236, and 0.216 UI/mL in descending order) for six days. Temperature profiling revealed optimum endoglucanase activity at 25 and 30°C. Maximum activity was observed at pH 5 and pH 6.

In the aim of valorizing aromatic and medicinal plants from Morocco, this work focuses on the chemical characterization and antimicrobial activity of Pelargonium asperum essential oil against 11 microbial strains causing problems in the medical and food domain. The chemical profile of the volatile oil was investigated by GC/MS. The major compounds were citronellol (26.98%), geraniol (14.12%), isomenthone (8.80%), linalool (4.97%), citronellyl formate (3.1%), followed by geranyl formate (4.07%) and guai-6,9-diene (4.24%). The results of antimicrobial activity by using the broth microdilution method indicated that essential oil of Pelargonium asperum exhibited significant antimicrobial activity against all tested microorganisms with the strongest inhibitory effect against yeasts. The MICs values ranged from 0.003% to 0.25% (v/v) for all strains, except Pseudomonas aeruginosa, which was least susceptible and inhibited by 2% (v/v). These results suggest that Pelargonium asperum oil could be used for the development of new antimicrobial agents.

In this work, the effect of three Thymus vulgaris extract fractions on physicochemical properties of cedar wood was examined. Indeed, hydrophobicity, surface tension components ΔGiwi, electron donor ( γ − ) and electron acceptor ( γ + ) parameters of untreated and treated wood were assessed using contact angle measurement. The samples treated with ethyl acetate, methanolic and hexane-ethyl-acetate fractions have indicated the hydrophilic character qualitatively and quantitatively with values of ( θ w = 17.1 ± 0.08°, ΔGiwi = 46.51 mJ/m 2 , θ w = 10.7 ± 0.40°, ΔGiwi = 35.36 mJ/m 2 and θ w = 31.1 ± 0.74°, ΔGiwi = 24.64 mJ/m 2 ) respectively, and more electron donor than untreated one. Moreover, the experimental and the theoretical prediction of Penicillium spores adhesion on untreated and treated substrates were also investigated. According to the values of the total free energy (Δ G Tot ), the adhesion of Penicillium commune and Penicillium commun on untreated wood was found favorable. In contrast, all treatments of wood surface were made the adhesion conditions unfavorable. The environmental scanning electronic microscopy (ESEM) has shown also that the adhesion of both Penicillium spores studied on the treated wood was too low. Thereby, a good correlation between the theoretical prediction and the adhesion experiments has been found. Based on these results, the natural products tested could be considered as an alternative source of bioactive molecules for limited and inhibited the adhesion of fungal spores on wood and hence, for its preservation.

The main objective of this work was to identify novel lipases of industrial interest. In this paper, Aspergillus flavus lipase (AFL) was isolated from the traditional tannery of Fez city in Morocco; it kept its stability even in the presence of high concentrations of detergent from 0 to 10 mM sodium deoxycholate (NaDC). Bile salts showed no inhibitory effect on the lipolytic activity, whereas the calcium salts showed a stimulating action on the lipase activity. Unlike most of the lipases which were quickly denatured at the lipid/water interface, the accumulation of free fatty acids at the oil/water interface did not affect the activity of the enzyme which effectively hydrolyzed the emulsified olive oil even in the absence of bile salts. Furthermore, AFL was more active on long chain triacylglycerols than on short chain triacylglycerols. This study allowed us to prove that AFL had the interfacial activation phenomenon. A 3D structure model of AFL was built and we have concluded that the ratio hydrophobic surface/hydrophilic surface was 51% versus 50%; it could be responsible for a higher tolerance to the presence of free fatty acids at lipid/water interface. Key words: Aspergillus flavus lipase (AFL), detergent, interfacial activation, free fatty acids, model.

Physicochemical characterization of microorganism is very important in a wide range of scientific and technological fields. In this study, we reported the isolation and the molecular identification of actinomycetes recovered from cedar wood decay. The isolates named H5 and H8 were identified by 16S rDNA sequencing and were shown to belong to the genus Nocardia and Streptomyces, respectively. Furthermore, physicochemical proprieties including hydrophobicity, electron donor/acceptor, and the Lifshitz–van der Waals (γLW) of these strains were evaluated using contact angle measurements. The results showed that Nocardia sp. (H5) had a hydrophobic (ΔGiwi = −78.56 mJ/m2) and a weak electron donor/acceptor character. In contrast, results from contact angle measurements showed that the surface free energy of Streptomyces strains (H2, H3, and H8) were ΔGiwi = 20.71 mJ/m2, ΔGiwi = 30.63 mJ/m2, and ΔGiwi = 15.35 mJ/m2, respectively, classifying these microorganisms as hydrophilic bacterium. Moreover, the three strain...

The aim of the study was to investigate the effect of crude extracts of Thymus vulgaris on wood surface physicochemical characteristics. Thus, the Lifshitz-van der Waals (), acid–base (surface tension components ΔGiwi, electron donor () and electron acceptor () parameters of untreated and treated wood were assessed using contact angle measurement. The main results showed that all T. vulgaris extracts are able to change wood surface properties. Indeed, the samples treated with the product obtained by maceration and ultrasound indicated the hydrophilic character (θw = 29.7 ± 0.3°, ΔGiwi = 17. 78 ± 0.48 mJ/m2 and θw = 18.2 ± 0.2°, ΔGiwi = 30.62 ± 0.31 mJ/m2) respectively, and had less contact angle values than that of untreated wood (θw = 86.0 ± 0.2°). In addition, this treatment has made the wood more donor ( = 44.76 ± 0.3 mJ/m2 and = 53.80 ± 0.3 mJ/m2) than the electron acceptor compared to sample control ( = 2.03 ± 0.04 mJ/m2). Finally, the effect of the extract obtained by ultrasound was found to be mor...

International audience; Layered double hydroxide (LDH) has attracted major interest as one of the most versatile drug delivery systems especially for adsorption capacity and/or controlled delivery property of bioactive agents owing to their combining features of biohybrid. ZnAl synthesized layered double hydroxide can offer a platform to immobilize various types of bioactive compounds, particularly berberine chloride (BBC). However, the immobilization reaction of berberine chloride into ZnAl-LDH was performed by direct co-precipitation method at different ratios of BBC/LDH. BBC-ZnAl-LDH biohybrids were characterized in terms of structure, surface morphology, in vitro drug release profile and antibacterial assay against various bacterial cells. The BBC biomolecules were attached by coordinate bond. Structural and microstructural characterization confirms that interaction of BBC with ZnAl-LDH occurs by adsorption rather than intercalation of BBC within LDH layers. The BBC release profiles from BBC-ZnAl-LDH had a longer release duration compared to the physical mixture, and the drug release seemed faster with the low ratio of BBC/LDH. BBC - ZnAl-LDH can be internalized into bacterial cells. In vitro experiments in PBS medium showed that BBC - ZnAl-LDH biohybrid had higher cytotoxicity and inhibitory effects against three pathogenic bacteria; Staphylococcus aureus CIP 543154, Pseudomonas aeruginosa A22 and Bacillus subtilus ILP 1428B upon the drug release profiles and its destructive potential depends on the loading BBC on the LDH layers. Nonetheless these results prove that the prepared BBC-ZnAl-LDH biohybrids retain the anti-bacterial character of the BBC molecules and are therefore potential modified drug delivery system (DDS).

International audience; Hydrotalcite (HT), also known as a layered double hydroxide (LDH) compound, has been widely used in past years in the formulation of drugs due to its specific properties including good biocompatibility, null toxicity, high chemical stability and pH-dependent solubility which aid in drug controlled release. In this work, berberine chloride (BBC) class antibacterial agent was immobilized into magnesium-aluminum LDH in order to improve the drug efficiency as well as to achieve the controlled release property. BBC molecules were immobilized into MgAl LDH through a conventional ion exchange reaction and co-precipitation method. The ion-exchange experiments of BBC on MgAl LDH were investigated with particular attention paid to the influence of the layer charge, the nature of the intercalated anion and the morphology. The immobilization efficiency was dependent upon the LDH properties and the immobilization process. Characterization by powder x-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy and contact angle measurements revealed that the interaction of BBC with MgAl LDH occurs by adsorption rather than intercalation of BBC within LDH layers. In vitro anti-bacterial tests were carried out using disc diffusion assay to prove the effectiveness of these novel biohybrid beads as a controlled drug delivery method. Consequently, the BBC-LDH co-precipitated formulation revealed an enhanced anti-bacterial activity compared to the ion-exchanged formulation not only due to an improvement of chemical stability and retained amount of BBC molecules but also due to the release property

In recent years, there has been a growing interest in researching and developing new antimicrobial agents from various sources to combat microbial resistance. Therefore, a greater attention has been paid to antimicrobial activity screening and evaluating methods. Several bioassays such as disk-diffusion, well diffusion and broth or agar dilution are well known and commonly used, but others such as flow cytofluorometric and bioluminescent methods are not widely used because they require specified equipment and further evaluation for reproducibility and standardization, even if they can provide rapid results of the antimicrobial agent's effects and a better understanding of their impact on the viability and cell damage inflicted to the tested microorganism. In this review article, an exhaustive list of in vitro antimicrobial susceptibility testing methods and detailed information on their advantages and limitations are reported.

The SiO2-CaO, SiO2-CaO-P2O5 and SiO2-CaO-P2O5-Ag2O glass systems were synthesized by the sol-gel technique and characterized with different techniques such as X-ray diffraction (XRD), Fourier Transform Infrared spectroscopy (FTIR), and Environmental Scanning Electron Microscopy (ESEM). In vitro bioactivity tests were performed in Simulated Body Fluid (SBF). The antibacterial action of 65S5Ag (65%SiO2 + 24%CaO + 6%P2O5 + 5% Ag2O) is attributed exclusively to the leaching of Ag+ ions from the glass matrix. The activity of SiO2-CaO-P2O5-Ag2O was compared with that of its binary and ternary counterpart glass system. The concentrations of Ag-bioglass, in the range of 0.05 mg/mL of culture medium, were found to inhibit the growth of these bacteria.