Isolation of actinomycetes producing bioactive substances from water, soil and tree bark samples of the north-east of Algeria Isolement d'actinomycètes producteurs de substances bioactives à partir d'échantillons d'eau, de sol et d'écorces d'arbres du Nord-Est de l'Algérie

Twenty-five strains of actinomycetes were isolated from samples of water, soil and tree barks collected at two sites located in the north-east of Algeria. Antimicrobial activity was tested using the agar cylinder method against three Gram-positive bacteria, three Gram-negative bacteria, three yeasts and three filamentous fungi. Among the 25 isolates 14 (56%) strains showed an activity against at least one of the test-bacteria studied and two (8%) showed antifungal activity. Ninety-three percent of the active strains were identified by the universal PCR as belonging to the Streptomyces genus and 7% to the Actinomadura genus. © 2005 Elsevier SAS. All rights reserved. Resume Vingt-cinq souches d'actinomycetes ont ete isolees a partir d'echantillons d'eau, de sol et d'ecorces d'arbres preleves de deux sites localises au Nord-Est de l'Algerie. L'activite antimicrobienne a ete effectuee contre trois bacteries a coloration de Gram positives, trois bacteries a coloration de Gram negatives, trois levures et trois champignons filamenteux. Elle a ete realisee par la technique de cylindres d'agar. Parmi les 25 isolats 14 souches (56%) ont montre une activite contre au moins une bacterie-test