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Sifaoui I.,Laboratoire Of Materiaux Molecules Et Applications | Chammem N.,Laboratoire Decologie Et Of Technology Microbienne | Abderrabba M.,Laboratoire Of Materiaux Molecules Et Applications | Mejri M.,Laboratoire Of Materiaux Molecules Et Applications
Journal of Materials and Environmental Science | Year: 2016

Olive products, such as oils, olives and leaves infusions, have been used in the past to treat many health problems. This study aims to develop a methodology for maximizing the efficiency of extraction of polyphenols from olive leaves. For this purpose, two experimental design approaches (a central composite design (CCD) and a mixture design) have been used. The optimal extraction parameters obtained from the CCD were: an incubating temperature of 58 °C, an extraction time of 54 min, a pH of 8, an agitation speed of 246 rpm, and a liquid-to-solid ratio of 77:1. Under the over mentioned conditions, the phenolic compounds content has increased two fold.

Hamida K.,Laboratoire Decologie Et Of Technology Microbienne | Faten K.,Laboratoire Decologie Et Of Technology Microbienne | Soumya E.A.,Center University Regional nterface | Saad I.K.,Center University Regional nterface | And 2 more authors.
Journal of Adhesion Science and Technology | Year: 2013

The initial microorganism adhesion on substrate is an important step for biofilm formation. The surface properties of the silicone and Bacillus cereus were characterized by the sessile drop technique. Moreover, the physicochemical properties (hydrophobicity; electron donor/electron acceptor) of surface adhesion and the impact of bio adhesion on the silicone were determined at different time of contact (3, 7, and 24 h). The results showed that the strain was hydrophilic (Giwi = 3.37 mJ/m2), whereas the silicone has hydrophobic character (Giwi =-68.28 mJ/m2). Silicone surface presents a weak electron-donor character (γ - = 2.2 mJ/m2) conversely to B. cereus that presents an important electron donor-parameter (γ - = 31.6 mJ/m2). The adhesion of B. cereus to silicone was investigated using environmental scanning electron microscope and image analysis was assessed with the Matlab® program. After 3 h of contact, the data analysis, confirmed the bio adhesion with an amount of 9.6105 cfu/cm2 adhered cells. After 24 h, the percentage of silicone covered reached 93%. Furthermore, despite the difference in hydrophohbicity, the interaction between B. cereus and substrata was favoured by the thermodynamic model of adhesion (ΔG adhesion < 0). The real time investigation of the effect of B. cereus adhesion on the physicochemical properties of silicone has revealed that the substrata becomes hydrophilic (θ° = 47.3, ΔGiwi = 23.7 mJ/m2), after 7 h of contact. This bio adhesion had also favoured the increase of electron donor/acceptor character of silicone (γ - = 53.1 mJ/m 2 and γ + = 5.3 mJ/m2). © 2013 Taylor & Francis Group, LLC.

Ksontini H.,Laboratoire Decologie Et Of Technology Microbienne | Kachouri F.,Laboratoire Decologie Et Of Technology Microbienne | Hamdi M.,Laboratoire Decologie Et Of Technology Microbienne
Indian Journal of Microbiology | Year: 2013

Bacillus cereus is a food pathogen that can attach on most of the surfaces and form biofilms, which facilitate the persistence and resistance toward antimicrobials. The aims of this study were (i) to characterize the structural dynamics of B. cereus sessile growth in two nutritional environments (with or without a nutrient flow), and (ii) to evaluate the impact of bio adhesion of Lactococcus lactis on B. cereus biofilm. Significantly greater biofilm volume and thickness were observed under dynamic conditions than under static conditions after 48 h and B. cereus biofilm was highly organized. The variation of physico-chemical characteristics of silicone by B. cereus bio adhesion favours the adhesion of hydrophilic Lc. lactis on the surface adhered by biofilm. Lc. lactis was able to adhere to silicone surface and produce biofilm obviously exhibited a significant reduction of B. cereus adhered cells up to nine orders of magnitude after 48 h of contact with competitive activity for nutrient and oxygen. This study constitutes a step ahead in developing strategies to prevent microbial colonization of silicone with lactococcal protective biofilm. © 2013 Association of Microbiologists of India.

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