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Quorum sensing is a communication system based on the actions of chemical signal molecules depending on the density of the cell population. These molecules are widely considered as effectors of the gene expression of several virulence factors. As a result, it has attracted a lot of attention because of its possible applicability as a target for treating infections. This review attempts to give a description of this system on gram negative bacteria specifically on Acinetobacter baumannii as an important nosocomial pathogen. Additionally, quorum sensing in biofilm will be also treated because it is considered as the origin of several chronic infections. Numerous studies have been carried out to prove the role of inhibitors in the disruption of quorum sensing, known as quorum quenching. Quorum quenching is a new strategy to eradicate bacterial infections due to the crucial intervention of quorum sensing in different virulence factors and particularly in the biofilm formation.

This study examined the gastrointestinal parasitological status of three endangered Sub-Saharan antelope species (Addax nasomaculatus, Oryx dammah, Gazella dorcas) hosted at Souss-Massa National Park in Morocco. A total of 254 faecal samples (80 samples from the addax population, 81 from the oryx population and 93 from the dorcas population) were analysed to determine the prevalence and the intensity of the parasites in host faeces (expressed as the mean EPG: egg per gram), using microscopic methods (Flotation and McMaster) and the molecular identification of parasites using PCR and sequencing of the second internal transcribed spacer region of the rDNA (ITS-2).The prevalence results in the addax, oryx and dorcas gazelle were 43.7%, 2.4%, and 61.3%, respectively, for Nematodirus spp.; 21.2%, 12.3%, and 16.13%, respectively, for Trichuris spp.; and 36.2%, 39.5%, and 53.7%, respectively, for other, undistinguished strongylids.The means of EPG values for parasites in addax, oryx and dorcas gazelle were 8.9, 2.4, and 61.3, respectively, for Nematodirus spp.; 4.3, 2.4, and 4.8, respectively, for Trichuris spp.; and 18.1, 16.6, and 50.1, respectively, for other undistinguished strongylids. Sequencing of the ITS-2 rDNA region of the isolated parasites allowed the identification of Camelostrongylus mentulatus and Nematodirus spathiger in these three antelope species. We can U studiji je sprovedeno ispitivanje parazitološkog statusa intestinalnog trakta kod tri ugrožene vrste subsaharske antilope (Addax nasomaculatus, Oryx dammah, Gazella dorcas) koje su se nalazile u Souss-Massa nacionalnom parku u Maroku. Da bi se ispitala prevalencija i intenzitet infestacije parazitima kod životinja, ukupno je ispitano 254 uzoraka fecesa (80 uzoraka iz addax populacije, 81 uzoraka iz orix populacije i 93 uzoraka iz dorcas populacije) pri čemu su rezultati prikazivani kao srednja vrednost EPG (jajašca parazita po gramu fecesa). Korišćene su mikroskopske metode (Flotacija i McMaster) kao i molekularna identifi kacija parazita upotrebom PCR testa i sekvencioniranjem rDNK (ITS-2). Rezultati prevalence Nematodirus spp kod addax, oryx i dorcas gazela bili su: 43,7%, 2,4% odnosno 61,3%; za Trichuris spp vrste 21,2%, 12,3% i 16,3%, a za strongilidne vrste koje nisu mogle da se determinišu: 36,2%, 39,5% i 53,7%. Srednje EPG vrednosti za parazite kod adax, oryx i dorcas gazele bili su za Nematodirus spp vrste 8,9, 2,4 i 61,3; za Trichuris 4,3, 2,4 i 4,8 a za na strongilidne vrste koje nisu mogle da se determinišu, 18,1, 16,6 odnosno 50,1. Rezultati sekvencioniranja ITS-2 regiona rDNK izolovanih parazita omogućio je identifi kaciju Camelostrongylus mentulatus i Nematodirus spathinger u navedene tri vrste antilopa. Može da se zaključi da su infestacije parazitima kod ove tri vrste antilopa na podnošljivom nivou pri čemu je po prvi put dijagnostikovana infestacija antilopa u Maroku sa Camelostrongylus mentulatus i Nematodirus spathinger

Aims — The purposes of the present work were to study the biofilm formation of Pseudomonas aeruginosa on stainless steel (316 and 304) and to investigate the effectiveness of sodium hypochlorite with different concentrations after 5 min of treatment, against P. aeruginosa biofilm formed on the same substrata. Methods — The methods used in this study were plate count method (PCM) and atomic force microscopy (AFM). Results — The results obtained using PCM showed that bacteria adhered more to stainless steel 316 than stainless steel 304. Furthermore, sodium hypochlorite was effective against cells of P. aeruginosa adhered to stainless steel 304 at the concentration of 0.5 %, but it was not effective against the ones adhered to stainless steel 316 until the concentration of 1%. The AFM results appeared that some bacteria still adhered to two types of stainless steel after sodium hypochlorite treatment at all concentrations. Conclusion — The type of surface and the disinfectant concentration have an effect on the efficiency of the disinfectant against biofilm. In addition the PCM and AFM do not give the same results.

This study aims to understand the relationship between capabilities of Escherichia coli strains to form biofilm and serotype groups expressed on cell surface. Sixteen strains of E. coli were originally isolated from different food processing lines in different Moroccan cities. Strains serotyped based on their O (somatic), H (flagellar), and K (capsular) surface antigen profiles using different antiserums. Biofilm assays carried out in 96-well microtiter dishes using the method of O’Toole et al. Our results show that no clear relation observed between origin and serotype groups. In the other hand, we observed that not all studied strains were able to form biofilm. Furthermore, combination of antigens H40 and K11 appears to be involved in biofilm formation. In fact, the H antigen seems to be implicated in the placement of the bacterial cells near the surface and the K antigen may play a role in physicochemical interactions between bacteria and inert surface.

The initial interaction between microorganisms and substrata is mediated by physicochemical forces, which originate from the physicochemical surface properties of both interacting surfaces. In this context, we have determined the physicochemical proprieties (hydrophobicity, electron-donor and electron-acceptor) of 37 isolates belonging to three genres of bacteria: Pseudomonas spp., Staphylococcus spp. and some species of Enterobacteriaceae isolated from various surfaces of the equipment and materials used in health establishment catering services. The physicochemical properties of these isolates were determined by contact angles measurements via Sessile Drop Technique. The results revealed that 62% of all bacteria studied exhibit a hydrophilic character (ΔGiwi >0) and other strains have a hydrophobic character (ΔGiwi

The initial interaction between microorganisms and substrata is mediated by physicochemical forces, which in turn originate from the physicochemical surface properties of both interacting phases. In this context, we have determined the physicochemical proprieties of all microorganisms isolated from cedar wood decay in an old monument at the Medina of Fez-Morocco. The cedar wood was also assayed in terms of hydrophobicity and electron donor-electron acceptor (acid-base) properties. Investigations of these two aspects were performed by contact angles measurements via sessile drop technique. Except Bacillus subtilis strain (Giwi 0) and can therefore be considered as hydrophilic while cedar wood revealed a hydrophobic character (Giwi = 58.81 mJ m−2). All microbial strains were predominantly electron donor. The results show also that all strains were weak electron acceptors. Cedar wood exhibits a weak electron donor/acceptor character. Based on the thermodynamic approach, the Lifshitz-van der Waals interaction free energy, the acid-basic interactions free energy, the total interaction free energy between the microbial cells and six different wood species (cedar, oak, beech, ash, pine and teak) in aqueous media was calculated and used to predict which microbial strains have a higher ability to adhere to wooden surfaces. Except of weak wood, for all the situations studied, generalizations concerning the adhesion of the microbiata on wood species cannot be made and the microbial adhesion on wooden substrata was dependent on wood species and microorganisms tested.

The adhesion of Bacillus subtilis and Bacillus sp. isolated from Fez cedar wood decay has been investigated. Furthermore, the physicochemical proprieties including hydrophobicity and electron donor/electron acceptor (Lewis acid–base) of both bacteria and substrata were evaluated using contact angle measurements. The results show that Bacillus subtilis has a hydrophobic character (ΔG iwi = –20 mJ/m2). In contrast, Bacillus sp. exhibits a hydrophilic (ΔG iwi = –20 mJ/m2), electron donating (γ–) and weakly electron accepting (γ+) character. With respect to the substrata surface, we found that the cedar wood used in this work, was hydrophobic in character, having relatively more electron-donor that electron-acceptor properties (γ– = 6 ± 4 mJ/m2; γ+ = 0 ± 3 mJ/m2). The phenomena of adhesion were observed by environmental scanning electron microscopy (ESEM) and cell adhesion was quantified using a Matlab program. The analysis of images obtained by ESEM show that the both cells was able to adhere to the wood sub...

The initial interaction between microorganisms and substrata is mediated by physicochemical forces, which in turn originate from the physicochemical surface properties of both interacting phases. In this context, we have determined the physicochemical proprieties of all microorganisms isolated from cedar wood decay in an old monument at the Medina of Fez-Morocco. The cedar wood was also assayed in terms of hydrophobicity and electron dono-r-electron acceptor (acid-base) properties. Investigations of these two aspects were performed by contact angles measurements via sessile drop technique. Except Bacillus subtilis strain (deltaGiwi0), all strains studied showed positive values of the degree ofhydrophobicity (deltaGiwi0) and can therefore be considered as hydrophilic while cedar wood revealed a hydrophobic character (deltaGiwi = -58.81 mi m(-2)). All microbial strains were predominantly electron donor. The results show also that all strains were weak electron acceptors. Cedar wood exhibits a weak electron donor/acceptor character. Based on the thermodynamic approach, the Lifshitz-van der Waals interaction free energy, the acid-basic interactions free energy, the total interaction free energy between the microbial cells and six different wood species (cedar, oak, beech, ash, pine and teak) in aqueous media was calculated and used to predict which microbial strains have a higher ability to adhere to wooden surfaces. Except of weak wood, for all the situations studied, generalizations concerning the adhesion of the microbiata on wood species cannot be made and the microbial adhesion on wooden substrata was dependent on wood species and microorganismstested.