Effect of Some Physical Factors on Natural Biosynthesis by Streptomyces spp

Aims: This study was performed to detect the effects of certain environmental conditions mostly physical ones on the biosynthesis of secondary metabolites produced by Streptomyces spp.
Study Design: Interventional study.
Place and Duration of the Study: Department of biology, College of science, Al-Mustansiriya University, Baghdad ,Iraq between February 2012 and December 2012.
Methodology: eight pure Streptomyces isolates, that produce antibiotics ,were exposed to different ranges of temperature, pH, aeration and radiation to elicit the optimum physical conditions for the biosynthesis of their secondary metabolites by estimating the diameter of inhibition zone of the growth on an isolate of E. coli on the nutrient broth and nutrient agar media after it`s inoculation with these products compared to control ones.
Results: The optimum growth temperature, pH, and aeration for the growth of Streptomyces were (28-32)ºC, (6.5-7.5) and 250 RPM respectively. Exposure to radiation for a period of 10 minutes had a lethal effect on Streptomyces but various responses were noticed upon exposure to radiant for less than 5 minutes depending on the species kind.
Conclusion: The production of antibiotics as a secondary metabolites by Streptomyces species could be enhanced by optimizing the physical factors affecting their growth like Temperature, pH, aeration and radiation.