Isolement et caractérisation des Actinomycètes productrices des antibiotiques et des lipides, et mise en évidence de leurs pouvoirs antibactériens vis-à-vis Pseudomonas aeruginosa et Bacillus subtilis

Abstract

Four actinomycetes strains were isolated from different soil samples , which are located in Ouillis area (Mostaganem) .After purification of actinomycete strains, a series of biochemical and physiological tests performed .Icoculums of the different isolates, were used in the production of two metabolites (Antibiotics, oil). Anevaluation of the antibacterial activity of extracts (ATB, oils) against two pathogenic strain Pseudomonas aeruginosa ATCC27853 and Bacillus subtilis ATCC6633 is followed by the disk method. Macroscopic and microscopic observations confirm that the four isolates exhibit the characteristics of Streptomyces sp, colonies of different diameters of 2 to 5 mm. Bacteria are at Gram positive; their myceliums diffuse different pigmentations. Physiological tests (starch, casein, etc.) and biochemical tests (citrate, lecithin...) are positive except for a few which are negative. The tests show that the four strains are bioactive. The yields of antibiotics and oils are respectively (0.26; 0.08; 0.07 and 0.06 g) and (18.18; 12.35; 4.55 and 2.64g). Antibacterial activity against two pathogenic germs is confirmed by antibiotic results, with inhibition zones varying for two extract [(0.70 ± 0,20 to 1.60 cm ) and (0.15 à 1.65 ± 0.15 cm)] et [(0.65 ± 0.05 to 1.30 cm) and (0.70 to 1.60 ± 0.10 cm)] and more. The CMIs of the two extracts obtained respectively correspond to concentrations (0.0012 g/l to 0.0005 g/l) and volumes (20 μl to 40 μl and 10 μl to 20 μl). It is preferable to deepen this study by other methods of extracts and purifications for a better exploitation of the strains.