Why 0.9% saline solution is used for the preparation of serial dilution or culture suspension.

• 0.9%  Saline solution is the best dilution for cell count.
• Saline water isotonic solution (no swelling or shrinking of cell) same as cell protoplasm, minimizes the chances of cell death.
• Phosphate buffer saline (PBS) solution also suitable for serial dilution preparation.
• Buffered sodium chloride peptone (BSCP) solution or peptone solution is not suitable for serial dilution because it supports growth and after utilizing the nutrients (peptone) bacterial cell die.
• Saline is 0.9% sodium chloride(Nacl) solution.
• Serial dilution or culture suspension used saline solution (0.9% Nacl) because 0.9% sodium chloride (Nacl) solution is isotonic in nature.
• In isotonic solution the concentration of solutes remains the same both inside and outside of the microbial cell and cells remains at their usual osmotic pressure.
• But water is hypo tonic in nature in nature in which the concentration of solute is grater inside the cell than outside and due to this water try to enter inside the bacterial cell.