The document describes an experiment to create and validate a mathematical model of the growth curve of E. coli bacteria after exposure to thermal shock at different temperatures. It discusses how temperature, initial bacterial concentration, and other factors affect the growth and decay rate of E. coli. The experiment subjects E. coli to thermal shock at temperatures from 45-70°C and measures its growth curve at 37°C compared to a control group grown at 37°C. The data will be used to create a growth curve model and compare the experimental and modeled curves.

1. Team 3
March 31, 2014

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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