Recall the equation governing bacterial growth
N=N0 *2n (n= # generations)
Explain why the progression of bacterial growth looks linear on a
semi-log plot
one axis is linear, the other is logarithmic
Calculate the generation time or the number of generations per hour
of a culture based on a given plot
g=1/v (v= # generations per hour)
Describe what happens in the four growth phases of batch cultures
Lag: adjust to medium
Exponential: cell & mass double in each generation
Stationary: balance between cell division and death
Death: cells start dying
Explain what parameters determine the presence and duration of the
lag phase
nature of new medium
where bacteria are coming from
if bacteria need to turn on genes (complex to minimum medium)
health of cell (i.e. coming from exponential vs death phase)
Explain what parameters control the growth rate in exponential phase
Faster growth rate in complex medium than in minimum medium
Explain parameters that can cause the stationary phase
run out of nutrients
accumulate too much waste
Explain Liebig�s law of the minimum
the concentration of the limiting nutrient affects the growth rate
& growth yield. Increase growth rate as increase concentration of
limiting nutrient until saturation when only more yield is made
Explain how growth factor bioassays work
Used in food industry; give certain amount of known growth factor in
medium (i.e. thiamin) that organism needs and see if it grows
Recall the key points describing bacterial growth in chemostats
Flow in = flow out
constant volume, pH, aeration
growth rate= dilution rate
dilution rate=flow rate/chemostat volume
Steady state; cell density & nutrients are constant
cell density is controlled by flow rate & limiting nutrient concentration
Explain how cell density is controlled by flow rate and limiting
nutrient concentration*
...
Explain why the bacterial concentration remains constant in the
steady state region of chemostat function*
Bacteria are washed out at a dilution greater than .75
Explain why the cell output increases while the bacterial
concentration remains constant in the steady state region of chemostat function*
cell density is controlled by flow rate & limiting nutrient concentration