Antitumor and Antimicrobial Activity of Antibiotic produced by Streptomyces spp.

 Actinomycetes produce a wide range of secondary metabolites and more than 70% of the naturally derived antibiotics that are currently in clinical use are derived from soil Actinomycetes and increasing of the pathogens resistant against antimicrobial agents becomes a health problems, so the current study was aimed to isolation of local Streptomyces spp. that is capable of producing secondary metabolite and investigate their biological antimicrobial and anticancer activities. Thirty five soil samples collected in Iraq area, out of Thirty five soil samples were screened, only (60%) of them harbored potential
Streptomyces. All isolates were tested for antimicrobial activities. Among all suspected Streptomyces candidates, only seven isolates (Bag3, Bag4, Bag7, Naj2, Naj9, Bab2 and Bab5) were able to inhibit the growth of tested microorganisms. Best media composition for enhancing the production of antimicrobial metabolites, four different broth media ISP1, ISP2, ISP4 and ISP5 were used, ISP2 revealed the best results (inhibition zone) among all used media. The MICs potential against Staphylococcus aureus and  Escherichia coli were 16 and 32 µl/ml respectively, the extracellular crude extract show strong
inhibitory activity against Gram-positive bacteria and moderate inhibitory activity against Gram-negative bacteria. In addition, The antitumor activities were determined by MTT assay, which indicated Bag3 possesses a powerful effect against used cancerous cell lines, especially against (Hep G2) by inhibiting 65.75% (400 µg /ml) of cancer cells after 72 hours of incubation, while against the (SUN16) 42.84% (400 µg /ml)   and against the WRL-68 (normal cell line) 13.43% (400 µg/ ml)  this indicate the effect of extracellular crude extract was achieved with concentration -dependent manner (dose dependent) This means that the isolated bacteria (bag3)  have little effect on normal cells, because we need  high concentrations to effect on the normal cells. The results of the optimization experiments, such as incubation period, pH, salt tolerance (NaCl) and temperature, revealed that the 4 days incubation, at pH 7.5, 1% of NaCl tolerance and temperature 30°C .HPLC analysis was done to detect the concentration of important active compounds present in the extracellular extract of Streptomyces. The HPLC of extracellular crude extract of (Bag3) was showed five different antibiotics (Tetracycline, Streptomycin, Neomycin, Vancomycin, Kanamycin)   which have the same retention time of the sample in compare with a standard but with different area.