الاحتلال الفرنسي لتونس وتوقيع معاهدة باردو عام 1881 والموقف العثماني منه عام 1881م

تعود الأطماع الفرنسية في تونس الى عهد بعيد ففي عام 1270م قام الملك لويس التاسع حملة عسكرية على تونس كان مصيرها الفشل، وبعدها تمكنت فرنسا من فرض معاهدة عام 1685م على تونس تخولها أحقية الامتيازات على بقية الدول الأخرى لكن بعد الاحتلال الفرنسي للجزائر عام 1830 أولت فرنسا اهتماماً خاصاً لتونس التي عدتها امتداداً للجزائر من الجبهة الشرقية واخذت فرنسا تخلق الذرائع لاحتلال الأيالة التونسية. وكثرة المشاكل على الحدود الجزائرية التونسية التي أعطت الذريعة لفرنسا في حشد قواتها العسكرية للدخول الى أرض الأيالة وطلب الباي الحكومة الفرنسية لحل المشاكل ودياً, ومعاقبة المشاكسين من قبله, لكن الحكومة الفرنسية رفضت ذلك وأرسل حاكم تونس برقية الى حكومة اسطنبول طالباً منها التدخل لاحتواء المشكلة حيث كانت الايالة التونسية تابعة اسمياً للدولة العثمانية.

Characterization of Microbial Biodegradation of Isoproturon under Field and Laboratory Conditions

Isoproturon [3-(4-isopropylphenyl)-1,1-dimethylurea (IPU)], one of the phenylurea herbicides, is extensively used across the globe in agricultural fields to overcome the pre- and post-emergence of broad leaf weeds in cereal cultures. Intensive use of IPU is becoming a source of ground and surface water contamination. Several problems including cancer, endocrine disruption and inhibition of growth in humans, animals and plants are related to IPU toxicity. Keeping in view the environmental concerns associated with IPU, there is a need to develop the strategies for removal of IPU from our environment. In this regard, the present study was conducted firstly to estimate the potential of natural adapted microbial communities for biodegradation of IPU within the agricultural fields of Shorkot, Faisalabad and Sahiwal repeatedly exposed with this herbicide. The in-field spatial variability in IPU degradation within the field was correlated with the prevailing physicochemical properties of the respective soils and was found positively correlated with the organic matter content, total organic carbon as well as the abundance of culturable heterotrophic microorganisms and negatively correlated with the pH. The soil showing a good potential for removal of IPU was used to isolate the bacterial strain having the capability for biodegradation of this herbicide through enrichment culturing using IPU as a sole source of C and N. In this study, a bacterial strain designated as Sphingobium sp. S29 was found to have the potential for biodegradation of isoproturon. The sequence of whole genome of Sphingobium sp. S29 was also sorted using CLC for the functional IPU degrading genes and a putative pdmAB gene potentially involved in the initial steps of IPU degradation was identified. The strain S29 had the potential to degrade known metabolites of IPU including monodemthylisoproturon, didemtheyl-isoproturon and 4-isopropyl aniline as well as other structurally related phenylurea herbicides including diuron and chlorotuluron. The biodegradation of IPU by this strain was optimal under shaking at 30˚C and at 8.0 pH. The bioaugmentation study of the isolated bacterial strain carried out in soil microcosms revealed that this strain has a good potential for biodegradation of isoproturon in the soil in the presence of 24% moisture content and at 30 ˚C. Based on the findings of this study, it might be concluded that the isoproturon dissipation in the agricultural fields in variable not only from field to field but also at different points within the same field thanks to the prevailing physicochemical biological properties of the soils. Moreover, it can also be concluded that the strain Sphingobium sp. S29 can serve as a potential candidate for devising the strategies for bioremediation of the soils contaminated with isoproturon.