Evaluation of Antimicrobial Pigment Produced by Streptomyces coeruleorubidus

The bacterial pigments are secondary metabolites that help the producer to survive in different environments. The bacterial pigments have shown different properties such as antitumor, anticancer and antimicrobial effects. The present study was conducted to isolate soil origin Actinomycetes and to evaluate their antimicrobial pigments. In total, eighty seven soil samples were collected from different areas in Kazeroun city, Iran. The samples were serially diluted (10^-1-1 to 10^-7) and 0.1 mL of each dilution was streaked on SCA and ISP2 media and incubated at 30C^° for 5 days. Then pigmented Actinomycetes were selected and subjected for propagation and pigment extraction using different solvents. To continue the experiments, the antimicrobial property of each pigment was evaluated against Staphylococcus aureus, Bacillus cereus, Escherichia coli, Pseudomonas aeruginosa, Shigella dysentriae, Citrobacter ferundii, Klebsiella peumoniae, Serratia marcecens, Aspergillus sp. and Candida albicans. Furthermore, identification of the promising strain was verified by 16srDNA gene sequencing method and finally different groups in the pigment structure were determined by TLC and reagent spray tests. The results obtained indicated that out of all the isolated Actinomycetes strains, Streptomyces coeruleorubidus could produce pigment with antimicrobial property. Of all the microorganisms tested Staphylococcus aureus was more sensitive and Aspergillus sp., Candida albicans and E. coli were more resistant. Our finding concerning to structure of the pigment illustrated existence of alcohols, phenols and steroid groups in the pigment. Overall, soil origin Actinomycetes could produce pigments with antimicrobial property. Therefore, Actinomycetes pigments must be considered a special remedy for investigation in order to eliminate occurrence of antibiotic resistant microorganisms.