Introduction of Successive Mutagenesis and Medium Optimisation for Enhanced Production of Ascomycin from Bacteria

Ascomycin is an important pharmacological product whose industrial yield is primarily credited to a bacteria named Streptomyces hygroscopicus var. ascomyceticus. The current investigation conglomerates a sequential approach adopted to genetically modify the parent strain via physical and chemical mutagenesis. The agents which we have used for inducing mutation include UV radiations, EMS and NTG. We have evaluated the effect of different individual mutagens on the parent strain. Post several rounds of screening and establishment of stable strain, we have used it to inoculate the optimised production media. For optimization of medium components, Plackett-Burman (PB) design and one-variable-at-a-time method (OVAT) have been included. At each step of the different methodologies adopted, shake flask activity has been fruitful in understanding the effect of strain modification as well as medium optimization. We have quantified crude ascomycin using HPLC. Finally, we have been able to enhance the productivity of ascomycin from the maximum of 205 mg/L with the initial conditions to 755 mg/L as a result of successive mutations and optimized production media.