Comparative study of total reducing and total antioxidant capacity of Escherichia coli on different media composition obtained by response surface methodology

Anti-oxidants are compounds that act against oxidative stress, prevent DNA damage and lipid peroxidation which are usually the major causes of aging and many diseases including cancer, cardio vascular disorders etc. There are many anti-oxidant assays which are used to measure anti-oxidant potential but total anti-oxidant capacity (TAC) and total reductive capability (TRC) are more preferred because of ease to use, good reproducibility and accuracy. Media components were optimized through response surface methodology (RSM) and sixteen different media compositions were obtained at primary level. These media compositions were used for TAC and TRC antioxidant assays.The highest reducing power activity was observed in the form of absorbance in media number 4 (0.0275 for 10 min) in wet biomass and for media number 6 (0.0244 for 10 min) in dry biomass. After 30 min, highest reducing power was reported in media number 5 (0.0286) in wet biomass and for dry biomass it was in media number 6 (0.0230). Total anti-oxidant capacity showed the higher percentage inhibition of microbial growth for wet biomass in media number 4 and media number 13 and for dry biomass, the highest percentage inhibition was in media number 5. Therefore, it was observed that media have same nutrients but different compositions which directly affect the level of TAC and TRC. Hence it is an important parameter that before experiments, media components must be optimized by RSM.