Lab 11: Effect of Osmotic Pressure on Bacterial Growth

name the three species being used in this experiment and discuss where all three species live normally.

Staphylococcus aureus, skin

Bacillus cereus, soil

Escherichia coli, colon

predict the species that can tolerate the highest concentration of salt

Staphylococcus aureus

what do you call a species that lives at high salt concentrations?

halophiles

which species used in our experiment was able to live in a moderate salt concentration?

Staphylococcus aureus

name the solute (be specific) that is being used in our experiment

sodium chloride

which salt concentration was used as the control? based on the scale used, how is the growth rated at this concentration?

0% nutrient agar, normal, control level growth (+++)

+++

normal, control level growth

++

medium level growth

+

low level growth

0

no growth

what helps the hypotonic to not burst

cell wall

osmosis

movement into or out of a cell

isotonic

concentration of solute inside and outside the cell is equal, no net movement

hypotonic

concentration of solute inside the cell is greater than outside, net gain of water for the cell

hypertonic

more solute outside the cell than inside, water moves out of the cell and shrinks (plasmolysis)

osmophiles

can tolerate more than 1 solute

osmolarity

how much solute was dissolved in the solvent