Five new strains MFB11, MFB20, MFB21, MFB23 and MFB24 of actinomycetes showed an intracellular hydrophobic pink red-like pigment production. These pigments present similar physico-chemical characteristics with anthracycline antibiotics of prodigiosin family. Nevertheless, negative antibacterial assay, Thinlayer chromatography (TLC) and interaction with organic solvents analysis of these pigments revealed their difference from known anthracycline antibiotics. Morphological, biochemical and gene coding 16S RNA sequence analysis allowed identification of the producer strains as Streptomyces coelicoflavus; known to produce important aminoglycoside antibiotics and other bioactive compounds but not anthracyclines red-like pigments. The identification of the five strains and physico-chemical properties of the produced pink red-like pigments are presented in this report.

This study aimed to examine the isolation of actinomycetes strains from unexplored Rabat neighbourhood soil followed by phenotypic diversity highlight to access their potential as novel bioactive compounds producers. Twenty nine actinomycetes strains were isolated from southeast of Rabat region. Morphological and cultural characterization, pigment production and antibacterial assay were carried out. All isolates (100%) were able to produce at least one non-diffusible pigment depending on the culture media. Twenty five (86.20%) isolates produce diffusible pigments, 6 (20.69%) produce melanoid diffusible pigments and 5 (17.24%) exhibited antibacterial activities. These results indicate an important potential of the actinomycetes isolated to produce polymorphic secondary metabolites.