To investigate biological control mains against phytopathogenic agent Pseudomonas syringae pv. tomato DC3000, responsible for bacterial speck, tests on the antibacterial activity of six essential oils were carried out. The essential oils, obtained by hydro distillation, was analyzed by gas chromatography (GC). The determination of the antibacterial activity of the essential oils carried out in-vitro using the well diffusion, micro atmosphere methods and the determination of MIC and CMB. Only essential oils of Cedrus atlantica had a negative activity against the bacterial strain. However, the overall results of this study suggested that Mintha pulegium, Thym vulgaris, Eucalyptus globulus essential oils had potential as a bio-pesticide for the control of bacterial speck disease of tomato. genetics and biotechnology (PGMB) [5]. This strain is characterized by the production of an endotoxin (pyoverdine) [10] and by its multiple resistance to antibiotics (rifampicin) [4]. The P. syringae pv. tomato cultures were grown on King's B and LB with rifampicin (50 g/ml) agar plates for strain verification.

The gammaproteobacterium Pseudomonas syringae pv. tomato DC3000 is the causal agent of bacterial speck, a common disease of tomato. The mode of infection of this pathogen is not well understood, but according to molecular biological, genomic and proteomic data it produces a number of proteins that may promote infection and draw nutrients from the plant. Glyceraldehyde-3-phosphate dehydrogenase (GAPDH) is a major enzyme of carbon metabolism that was reported to be a surface antigen and virulence factor in other pathogenic microorganisms, but its possible role in the infection process of P. syringae has so far not been studied. Whole-genome sequence analyses revealed the occurrence in this phytopathogenic bacterium of three paralogous gap genes encoding distinct GAPDHs, namely two class I enzymes having different molecular mass subunits and one class III bifunctional D-erythrose-4-phosphate dehydrogenase/GAPDH enzyme. By using genome bioinformatics data, as well as alignments of both DNA and deduced protein sequences, the three gap genes of P. syringae were one-step cloned with a His-Tag in pET21a vector using a PCR-based strategy, and its expression optimized in Escherichia coli BL21 to achieve high yield of the heterologous proteins. In accordance with their distinct molecular phylogenies, these bacterial gap genes encode functional GAPDHs of diverse molecular masses and nicotinamide-coenzyme specificities, suggesting specific metabolic and/or cellular roles.

A bacterial field isolate recovered from infected tomato plants in a green-house at Sidi Rehal, a region near Casablanca city (Morocco), was identified as the gammaproteobacterium Pseudomonas syringae pv. tomato DC3000 strain, the causal agent of bacterial speck. The bacterial isolate was characterized by morphological, biochemical and molecular biological tests, its growth curves carried out in various culture media, and its phytopathogenicity verified by infection tests. A screening was performed to evaluate the antibacterial activity of methanolic extracts of 12 selected Moroccan plants against the P. syringae pv. tomato DC3000 isolate, and Agar-well diffusion and Broth microdilution methods were used to determine minimum inhibitory and minimum bactericidal concentrations. Among the methanolic extracts tested, only those of Nigella sativa, Geranuim robertianum, Aizoon canariense and Rubia peregrine showed clear inhibitory and bactericidal activities, although the highest values were achieved with N. sativa, a plant used in Morocco as a spice, condiment and medicinal treatment.

Background The aim of this study is to assess the corrosion resistance behaviour of Nickel-Titanium-based orthodontic wires (NiTi) in different concentrations of Sodium Fluoride (NaF) and the corrosion’s inhibitory effect of the extracts of some medicinal plants (essential oils, hydrosols and extract). Material and Methods In this study we used NiTi (3M) and CuNiTi (ORMCO, 35°C, California) orthodontic wires. The following electrolytes were prepared: Lactate Ringer solution with additions of 0.1%, 0.5% or 1% of Sodium Fluoride and the extracts of different plants: Artemisia, Syzygium aromaticum (Clove) and Celtis australis. Corrosion resistance was studied using anodic potentiodynamic polarisation and electrochemical impedance spectroscopy measurements. At the end of the experiment, microscopic images of wires were performed. ANOVA test with the comparison of Bonferroni and Tukey tests were performed to elucidate comparisons among all groups. Results The higher sodium fluoride concentration is related to negative corrosion potential for both NiTi and CuNiTi orthodontic wire. Hydrosols are associated to positive values of corrosion potential. CuNiTi has a lower corrosion resistance than NiTi. Conclusions The prescription of toothpastes containing sodium fluoride should be reduced especially for patients wearing fixed orthodontic appliances. Eugenol may be considered as alternative of sodium fluoride for orthodontic patients for its anti-microbial and anti-corrosive effects. Key words: Corrosion behaviour, Sodium Fluoride, Nickel-Tatanium, orthodontic wires, corrosion inhibitors, aromatical plants.

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