Application of Low pH as a Curing Agent of Plasmid DNA in Streptomyces as Compared with other Agents


Fourteen strain of Streptomyces were obtained from a previous study and their identity was ascertained by using slide culture method that showed their aerial and earthy hyphae. Antibiotic susceptibility of the strains towards Nalidixic acid, Ampicillin, Chloramphenicol, Cefalexin, Rifamycin and Gentamycin were tested and the four most resistant were selected for subsequent analysis. Spontaneous curing was obtained as a control sample and we noticed (0-4%) curing percentage, after treatment of the isolates with acidic pH we noticed (22-100%) curing percentages towards the antibiotics understudy .Then we used various chemical and physical curing agents to compare them with acidic pH treatment. We found that elevated temperature, acridine orange (50g/ml), (100g/ml), SDS (50g/ml) and (100g/ml) had the ability to cure the isolates at various percentages (4-60%), (0-20%), (0-12%), (0-6%), (4-20%) respectively. This indicated that using the acidic pH has an effective curing ability to cure the plasmid DNA of Streptomyces much better than other well known curing agents .Low pH is also much easier and safer to handle as compared with chemical compounds that can be mutagenic to chromosomal DNA and harmful to the researcher himself .