S.coelicolor IQ54 is a producer of actinorhom-lik substances which is active against Staph.aureus, while S.aurofacens 8D is tetracyclines producer and active against Bacillus cereus and E.coli. These two antibiotics belong to same group (polyketide). these two Streptomyces species were used in the genetic analysis of antibiotic production and resistance. The study showed that the compositions of culture media effected the growth, colour of aerial, substrate mycelia, soluble pigment production and antibiotic production. The results showed that temperature has an effect on antibacterial activity of each of two Streptomyces species, against bacteria, the result indicated that the optimum antibacterial activity appeared at 28C°. Genetic crosses between IQ54 (str lins) anil SD (str' lin) were carried out and it was possible to obtain with following genetic constitution (str –lin). These recombinants showed different pattern of antibacterial activity from that observed by parents. Curing of S.aureofaciens SD by acridine orange indicated that cured colonies still produced of tetracycline antibiotics, while NaCl tolerance and antibiotic resistance of some antibiotics such as tetracycline was los after curing. Plasmid cannot detected in wild type and cured colonies.