RÉSUMÉ
Objective: To study the antimicrobial activity of actinomycetes isolated from sabkha of Kenadsa and identification of the isolate interesting. Methods: Eighteen strains were isolated, using four culture media from sebkha of Kenadsa (Bechar, Southwestern Algeria). Screening of antimicrobial activity consisted of two steps: in primary screening, antibacterial activity was determined by using the agar plug method against test strains; in secondary screening, better isolate which showed a good activity in the first screening was selected to extract antimicrobial substances. The antimicrobial activities of extracts were evaluated by using Kirby-Bauer disc diffusion method. Partial characterization of antimicrobial products was performed on the basis of chemical revelations, UV-vis spectrometry and infrared spectroscopy. The identification of isolate interesting was performed through morphological, chemical, biochemical and physiological characteristics. Results: All isolates showed antimicrobial activity against at least one microorganism test. One isolate, LAM143cG3, was selected for its broad spectrum and high antimicrobial activity. The isolate LAM143cG3 was identified as Spirillospora sp. The comparison between the species of this genus (Spirillospora rubra and Spirillospora albida) and our isolate indicated the existence of several physiological and biochemical differences which led us to suppose that this was a new member of this genus. Primary characterization of antimicrobial substances produced by the isolate LAM143cG3 indicated the presence of amines and phenols. The UV-vis spectrum suggested a nonpolyenic nature of substances secreted by our isolate, while infrared confirmed the presence of amine groups. Conclusions: The result of the present study revealed that sebkha of Kenadsa was rich in rare actinomycetes, that secreted interesting antimicrobial substance.