Effect of Osmotic Pressure on Bacterial Growth - Lab Practical 4

What is osmosis?

• The movement of water in order to balance the solutes on either side of the membrane, water moves since the solute cannot

Which way does water move if a cell is placed in a hypertonic environment (solution)?

• Water will move out of the cell

Which ways does water move if a cell is placed in a hypotonic environment (solution)?

• Water will move into the cell

What happens to bacteria when placed in a hypertonic solution?

• Most bacteria die with the loss of water (dehydration)

What happens to bacteria when placed in a hypotonic solution?

• Bacteria can survive since they have a cell wall to prevent them from bursting as water enters the cell

What is a halotolerant microorganism?

• If they prefer to grow in low salt concentrations but can continue to grow even in high salt environments

What is a halophile?

• If they require a high salt environment

Know the solute used in this lab (be specific and no chemical formulas)

• Sodium Chloride

Given a set of salt plates, be able to identify each species based on the growth pattern and which species is the halotolerant and which is the halophile

• Staphylococcus aureus (S. aureus)

• Halobacterium salinarum

Given a table like in the PPT, be able to identify each species based on the growth pattern and which species is the halotolerant and which is the halophile

• Staphylococcus aureus (S. aureus)

• Halobacterium salinarum