2. The purpose of this study is to create
and validate a mathematical model of
a growth curve of bacterial behavior
after thermal shock at various
temperatures
3. Escherichia coli (E. coli) is a type of bacteria
commonly found in the intestinal tracts of
large mammals
The growth and decay rate are also affected
by:
Temperature
Initial concentration of bacteria
Presence of antibacterial substances
pH levels
Oxidation reduction potential
4. In our experiment, we demonstrate how the
growth curve is affected by thermal shock
E. Coli grows well between 21oC to 50oC with
an optimum at about 37oC .
E. coli can divide every 20 minutes
At temperatures of 0°C (32°F) E. coli are
unable to divide, keeping the population
stable
E. coli is killed above 70°C (160°F)
5. Lag phase: the population remains temporarily
unchanged
Log phase: the cells divide at a constant rate
depending on temperature conditions
Stationary phase: the population
growth is limited by
temperature
Death phase: the
number of cells decreases
The E.coli Growth Curve
6. The growth curves of colonies shocked
at temperatures (45-650C) demonstrate
longer lag times but accelerated
exponential growth when compared to
a control grown at 37°C
7. WE WILL APPLY THIS
EQUATION TO CREATE THE
GROWTH CURVE MODEL[17]
Where:
(Nmin) = minimum
population of E.coli
(Nmax) = maximum
population of E.coli
r = Temperature-dependent
constant
C= Adjustment factor
N= number colonies at time t
8. Materials and Equipment
Spectrophotometer and cuvettes
Inoculation Loop
1000μL and 100μL micropipettes
Beakers and hot plates
Incubator (37oC)
Reagents:
Distilled water and deionized water
Culture of E.Coli
Nutrient broth as a food source
9. Thermal Shock:
Initially raise bacterial environment
temperature to 450C, 550C, 600C, and 700C
Growth continued at 370C after thermal shock
Control group grown at 370C
Measure growth
Create a concentration ladder
Measure cloudiness in a test tube as the number
of cells increase (turbidity) using a
spectrophotometer
10. Mintab and MATLAB software
Plot mathematical growth curve and
experimental growth curves
Regression analysis
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