1) A bacterial colony taken from an agar plate was precultured in 20 mL of 30 g/L Tryptic soy broth (TSB) medium at 30 °C for 12 h.Then, the precultured bacterial suspension was diluted 50 times with 30 g/L TSB medium and cultured again for 4 h at 30 °C.

- After bacteria recultured, I measure the OD of both bacteria. I got OD of 0.39 for S.A and OD of 0.42 for E.C. I need to adjust the bacterial suspension to a final optical density of 0.05 at 450 nm and measured using a spectrophotometer. How can I reduce my OD?