Bøger af Ilham Zahir

La biolixiviation est une technique consistant à utiliser des microorganismes pour libérer des métaux de valeur en faibles teneurs à partir des matériaux solides. Ce procédé est conditionné par plusieurs paramètres comme le pH acide, la température et l¿oxygène dessous. Il fait appel à deux mécanismes, direct et indirect.Par ailleurs, cette pratique pourrait être mise en place dans divers types de systèmes de lixiviation bactérienne, dont la biolixiviation en tas, la biolixiviation en cuve et la biolixiviation in situ. La réussite des microorganismes à mobiliser des métaux à partir des minerais est cohérente avec leur possession d¿un arsenal des gènes codant pour des enzymes impliqués dans le fonctionnement de la biolixiviation. En définitif, à mesure que les minerais plus riches s'épuisent dû à la demande mondiale croissante, l'importance de la biolixiviation devrait augmenter à l'avenir en exploitant, d¿une manière économiquement bénéfique et moins polluante à l¿environnement, les gisements de minerais à faible teneur en métaux.

Candida albicans is a polymorphic yeast commensal of the oral cavity as well as the digestive and genital tract. However, under certain conditions, it becomes opportunistic, leading to infections called candidiasis, which can be severe or even fatal, particularly in immunocompromised patients. Epidemiological data show that 82% of the world population is affected by C. albicans. Indeed, this fungus expresses several pathogenicity factors. Therefore, focusing on the pathophysiology of C. albicans, eventually allows to understand the host-parasite relationship as well as the mechanisms and causes involved in the transition of yeast from commensal to pathogenic state. The goal is to further understand the factors that contribute to virulence in order to avoid infection or limit recurrence. This work also presents the clinical aspect of candidiasis, their diagnostic methods as well as the treatments used and the mechanisms of resistance subsequent to the use of antifungal agents to finish with a set of preventive measures to be followed in order to limit the infection by C. albicans.

Tuberculosis remains among the most curable infectious diseases. In recent decades, the risk of contracting this disease has increased significantly due to the spread of the AIDS pandemic, which has also favored infections by atypical mycobacteria and has accentuated the emergence of multi-resistant bacilli, making the problem more worrying. Consequently, it is imperative to use a new alternative to overcome the current impasse and find new molecules with anti- mycobacterial effect with reduced toxicity and be compatible with existing anti-tubercular drugs. Thus, the herein investigation aimed to isolate and identify microorganisms secreting substances with antimycobacterial effect and to partially characterize their bio active compounds. We isolated 10 bacterial isolates from the various ecological niches able to inhibit mycobacterial growth and / or other Gram-positive and Gram-negative bacteria. Our study focused on four strains for which the crude extracts obtained by precipitation with ammonium sulphate and / or the organic solvents inhibited the proliferation of M. smegmatis. Partial purification was then perfomed according to the nature of the bio active(s) substance(s).