Growth kinetics comparison of the ΔpurD mutant and RB51 strain. O.D values at different time intervals when grow in non-enriched TSB medium without supplementation of adenine, guanine, thiamine and hypoxanthine. A, and in TSB enriched medium with supplementation of adenine, guanine, thiamine and hypoxanthine. B, Statistically significant differences in growth curve between parent RB51 strain and ΔpurD mutant was determined by using two-way ANOVA (***, P <0.05).