Activité antibactérienne de deux souches de Streptomyces sp. A12 et G46 contre des souches bactériennes multi-résistantes

Abstract

The goal of this work is to study the antibacterial activity and the production of antibacterial molecules of two new strains of actinobacteria of the genus Streptomyces named respectively, A12 isolated from sandy soil from Masaka province in Uganda and G46 isolated from a soil of a palm grove of El Atteuf.The Strain A12 belonged to the genus Streptomyces and it’s taxonomically closest to S. samsunensis M1463 T with a percentage of similarity of 99.50%. The study of the antibacterial activity tested against 23 target bacteria on solid ISP2 medium revealed that the strain A12 has an important activity against six Gram positive bacteria: Bacillus subtilis (ATCC 6633), Listeria monocytogenes (ATCC 13932), Staphylococcus aureus (43300), S. aureus (25923), S. aureus (639c) and S. aureus (MRSA 2). The strain G46 has the same antibacterial activity against bacteria tested by strain A12.The production kinetics of antibiotics were carried out in liquid media ISP2 and Bennett for 10 days and the optimal day of production for each strain by the well diffusion method which showed that the better antibacterial activity for A12 was observed on the fifth day and the third day for strain G46. The antibiotics were extracted with four organic solvents and the best extraction solvent were determined by antibiography against Listeria monocytogenes (ATCC 13932). The best result is obtained using ethyl acetate.