Effect of physical and chemical mutagens on biopolmer producing strains and RAPD analysis of mutated strains

摘要

Mutation (Latin mutare means to change) refers to any heritable change in nucleotide sequence of a gene of the organisms irrespective of altered pheno typic expression of characters of the organisms. Strain improvement can be carried out by physical, such as gamma-rays, x-rays and ultraviolet irradiation, and chemical, such as ethyl methane sulphonate(EMS) and nitroao-methyl guanidine (NTG). The best mutagen and conditions for its use are not identical for all organisms and can only be found by trial and error.The efficiency of alkylating mutagen treated bacterial isolates showed effective reactions depending on the duration of exposure. EMS mainly added the ethyl group to numerous positions on bases of DNA. Out of 20 primers screened, primer A9 was selected on the basis of robustness of amplification, reproducibility, scorability of banding patterns and was employed for diversity analysis. The primer yielded both intense as well as faint bands, and were scored for calculating similarity index values, so as to maximize the number of scorable characters. On the basis of the results obtained, all the four cultures namely, P.putida, B.megterium, E.coli and R.eutropha have higher activity on duration of exposure to UV light. When the period of exposure is for longer duration less will be the survival of the specific cells and all the mutant forms which has the ability to survive alone will remain forever. Similar results were found the Random Amplified Polymorphic DNA (RAPD), a PCR based method which could be used to distinguish strains within a species. Data analysis using bioprofile ID software revealed a variable similarity index between the native isolates and their respective mutants. This clearly illustrates that mutation had occurred in U.V treated and EMS treated isolates. Genetic analysis for identifying mutation using the primer A9 revealed a moderate genetic variability proving mutation.