A Participatory Agrobiodiversity Conservation Approach in the Oases: Community Actions for the Promotion of Sustainable Development in Fragile Areas

Rural development policies today include significant directions towards ecological transition and sustainability. Biodiversity plays a fundamental role, especially in fragile environments. The North African oases, for example, are socio-ecological structures with delicate balances in terms of natural resources, where the activation of participatory conservation approaches appears today to be very useful, aiming at long-lasting results. This type of approach was applied in the oasis of El Hamma, in Tunisia. The socio-ecological analysis was carried out through semi-structured interviews with different stakeholders of the oasis. The results were used to activate focus groups and to identify, in a participatory way, a conservation strategy for the species and the varieties at risk of erosion or disappearing. From this research, a wide spread of non-traditional date palm and vegetables emerged in a very diverse social context. These products were recognized as highly significant in terms of traditional knowledge by all stakeholders. Therefore, a Maison des semences and a public conservation center for perennial species were created, representing the first step of a participatory conservation model. Seeds of 11 traditional annual species, 10 date palm varieties and, in perspective, many other fruit species and vegetable varieties have been introduced into conservation.

Chemical composition and antibacterial activity of Algerian propolis against fish pathogenic bacteria

Five different varieties of propolis from four sites from Sétif region (East of Algeria) (Babor, Setif; Ain-Abbassa and El-Hamma), and one site from the center of Algeria (Tizi-Ouzou) were chemically analysed by gas chromatography-mass spectrometry. One hundred and two compounds were identified including aromatic acids, linear hydrocarbons and their acids, terpenes and alcaloïdes. Furthermore, the in vitro bacteriostatic and bactericidal activities of the aqueous extracts were evaluated against one Gram positive (Bacillus subtilis, used as probiotics in aquaculture) and two Gram negative (Vibrio anguillarum and Vibrio harveyi, pathogenic for fish) bacteria. The obtained results showed that all aqueous extracts of propolis inhibit the growth of B. Subtilis while the growth inhibition of fish pathogens was achieved when using higher propolis concentrations. These antibacterial properties would warrant further studies on the clinical applications of propolis in aquaculture field. Keywords: Bactericidal activity; Chemical characterization; Propolis; Vibrio.

L'inhibition de l'entartrage par les eaux géothermales du sud tunisien. Étude sur site

Une nappe d'eaux fossiles à grande profondeur (800 à 2 700 mètres) a été mise en exploitation dans le Sud-Tunisien pour alimenter une usine d'osmose inverse située à Gabès ayant une production de 15 000 m3 /jour, afin de lutter contre la désertification par irrigation et d'assurer le chauffage de serres pour la production de primeurs. La grande dureté (TH de l'ordre de 100 à 140 °F) de ces eaux géothermales a pour conséquence le colmatage rapide des conduites de distribution : 40 à 50 tonnes de tartre par forage, constitué essentiellement de carbonate de calcium, précipitent chaque année. Ce tartre est constitué d'aragonite comme le montrent la microscopie électronique à balayage et la diffraction des rayons X. Une technique électrochimique, la chronoélectrogravimétrie, permet d'étudier l'inhibition de l'entartrage par des composés de la famille des phosphates inorganiques, des phosphonates organiques et des polycarboxylates. La concentration efficace de chacun de ces inhibiteurs agissant par effet de seuil a été déterminée : elle est de l'ordre de 1,1 à 1,5 mg.l-1 pour l'eau du forage de EL HAMMA. Un essai sur le site de EL MANSOURA a été effectué en privilégiant un inhibiteur produit industriellement dans le Sud-Tunisien, le triphosphate de sodium. A la concentration de 1 mg.l-1 il évite l'entartrage du système de refroidissement de type cascade - piscines et des conduites de distribution.