ORIGINAL ARTICLE Isolation and partial characterization of pigment-like antibiotics produced by a new strain of Streptosporangium isolated from an Algerian soil H. Boudjella 1 , K. Bouti 1 , A. Zitouni 1 , F. Mathieu 2 , A. Lebrihi 2 and N. Sabaou 1 1 Laboratoire de Recherche sur les Produits bioactifs et la Valorisation de la Biomasse, Ecole Normale Supe ´ rieure de Kouba, Vieux-Kouba, Alger, Alge ´ rie 2 Laboratoire de Ge ´ nie Chimique, UMR 5503 (CNRS/INPT/UPS), Ecole Nationale Supe ´ rieure Agronomique de Toulouse, INPT, Castanet-Tolosan Cedex, France Introduction Since several decades, actinomycetes continue to serve as an important source of various kinds of antimicrobial metabolites. It has been estimated that approximately two-thirds of natural antibiotics have been isolated from actinomycetes, and about 75% are produced by members of the genus Streptomyces (Buckingham 1997; Newman et al. 2003). It is essential that the search for new antibiotics contin- ues, because of the toxicity of some currently used com- pounds and the emergence of resistant pathogens. Intensive programmes seeking for antibiotics are running worldwide. The approaches considered in these research programmes include the isolation of new antibiotics from actinomycetes other than the genus Streptomyces and the exploration of new and particular ecological systems. These actinomycetes constitute a minor component of the Keywords actinomycetes, antibiotics, antimicrobial activity, Streptosporangium, taxonomy. Correspondence N. Sabaou, Laboratoire de Recherche sur les Produits Bioactifs et la Valorisation de la Biomasse, Ecole Normale Supe ´ rieure de Kouba, B.P. 92, 16 050 Vieux-Kouba, Alger, Alge ´ rie. E-mail: sabaou@yahoo.fr 2006/0525: received 16 April 2006, revised 4 September 2006 and accepted 20 September 2006 doi:10.1111/j.1365-2672.2007.03280.x Abstract Aims: Identification of a new actinomycete strain Sg3, belonging to the genus Streptosporangium and partial characterization of the produced antibacterial activities. Methods and Results: The strain Sg3 was isolated from an Algerian Saharan soil and identified by morphological, chemotaxonomic and phylogenetic analy- ses to the genus Streptosporangium. The comparison of its physiological charac- teristics with those of known species of Streptosporangium showed significant differences with the nearest species Streptosporangium carneum. Analysis of the 16S rDNA sequence of strain Sg3 showed a similarity level ranging between 97% and 98Æ8% within Streptosporangium species, with S. carneum the most closely related. Strain Sg3 showed a red coloured antibacterial activity against gram-positive bacteria on several culture media. The purification of the red pigment by chromatographic methods led to the isolation of three active prod- ucts. The 1 H nuclear magnetic resonance (NMR), mass, infrared (IR) and ultraviolet-visible (UV-VIS) data of these molecules strongly suggested that they belonged to the quinone-anthracycline group with three or more rings. Conclusions: Strain Sg3 represents a distinct phyletic line suggesting a new genomic species. It produces antibacterial activities identified as quinone-anth- racycline aromatics. Significance and Impact of the Study: The quinone-anthracycline antibiotics are known for their antimicrobial and antineoplastic activities and are used in chemotherapy for the treatment of many cancer diseases. The present work constitutes the first stage of a whole series of studies to be realized on these antibiotics before arriving at a possible application. Journal of Applied Microbiology ISSN 1364-5072 228 Journal compilation ª 2007 The Society for Applied Microbiology, Journal of Applied Microbiology 103 (2007) 228–236 ª 2007 The Authors