Lab 6 Food BIO250
L
Microbiology
Student Name: Monilola Anigala
Access Code (located on the underside of the lid of your lab kit): AC-3BMK7G
Pre-Lab Questions
1. Escherichia coli is one of the most common causes of foodborne illness, yet it is also a
common microorganism found within the human gut. What explains this disparity?
While some types of E. coli bacteria are harmless and even play a beneficial
role in digestion, certain strains can produce harmful toxins and contaminate
food, leading to foodborne illness.
2. There are several foods and beverages listed in this lab that are created through the actions of
microorganisms. Name five of the foods and the specific microorganisms that are used to
make each of them.
Several delicious foods and beverages are created through the work of
microorganisms, including yogurt (produced by lactic acid bacteria), beer
(fermented by yeast), cheese (a result of lactic acid bacteria and rennet),
sauerkraut (preserved by lactic acid bacteria), and sourdough bread
(leavened by wild yeast and bacteria).
3. Using an online research tool such as the A-Z index on the CDC website, explain why Listeria
monocytogenes is a major threat to pregnant women and their developing fetuses, who are
ten times more likely to get sick than other demographic groups.
Pregnant women and their unborn babies face a significant risk from
Listeria monocytogenes, a harmful bacterium that can cross the
placenta and lead to miscarriage, stillbirth, premature delivery, or
severe health problems in the newborn.
, Lab 6 Food BIO250
L
Microbiology
EXPERIMENT 1: Assessing the Bacterial Load of Milk with Methylene Blue
Results Tables
Table 1: Time Required for Methylene Blue Color Change
Start Time/Date End Time/Date Time Elapsed
Milk Sample
(Step 10) (Step 11) (End Time-Start Time)
0 hours 10pm 10:30pm 30mins
1 hour 10pm 11:30pm 1.5hrs
3 hours 10pm 1am 3hr
4 hours 10pm 2am 4hrs
Post-Lab Questions
1. On average, which sample took the least time to become white? Why do you think this was
the case?
Among the samples, the one left at room temperature for four hours reached
a whitish state the quickest.
2. On average, which sample took the most time to become white? Why do you think this was
the case?
The sample stored at room temperature for zero hours took the longest time
to turn white.
3. How does refrigeration affect the number of bacteria present in milk?
Refrigeration keeps milk fresh for longer by slowing down the growth of bacteria.
4. How does pasteurization affect the number of bacteria present in milk?
Pasteurization kills bacteria in milk.
L
Microbiology
Student Name: Monilola Anigala
Access Code (located on the underside of the lid of your lab kit): AC-3BMK7G
Pre-Lab Questions
1. Escherichia coli is one of the most common causes of foodborne illness, yet it is also a
common microorganism found within the human gut. What explains this disparity?
While some types of E. coli bacteria are harmless and even play a beneficial
role in digestion, certain strains can produce harmful toxins and contaminate
food, leading to foodborne illness.
2. There are several foods and beverages listed in this lab that are created through the actions of
microorganisms. Name five of the foods and the specific microorganisms that are used to
make each of them.
Several delicious foods and beverages are created through the work of
microorganisms, including yogurt (produced by lactic acid bacteria), beer
(fermented by yeast), cheese (a result of lactic acid bacteria and rennet),
sauerkraut (preserved by lactic acid bacteria), and sourdough bread
(leavened by wild yeast and bacteria).
3. Using an online research tool such as the A-Z index on the CDC website, explain why Listeria
monocytogenes is a major threat to pregnant women and their developing fetuses, who are
ten times more likely to get sick than other demographic groups.
Pregnant women and their unborn babies face a significant risk from
Listeria monocytogenes, a harmful bacterium that can cross the
placenta and lead to miscarriage, stillbirth, premature delivery, or
severe health problems in the newborn.
, Lab 6 Food BIO250
L
Microbiology
EXPERIMENT 1: Assessing the Bacterial Load of Milk with Methylene Blue
Results Tables
Table 1: Time Required for Methylene Blue Color Change
Start Time/Date End Time/Date Time Elapsed
Milk Sample
(Step 10) (Step 11) (End Time-Start Time)
0 hours 10pm 10:30pm 30mins
1 hour 10pm 11:30pm 1.5hrs
3 hours 10pm 1am 3hr
4 hours 10pm 2am 4hrs
Post-Lab Questions
1. On average, which sample took the least time to become white? Why do you think this was
the case?
Among the samples, the one left at room temperature for four hours reached
a whitish state the quickest.
2. On average, which sample took the most time to become white? Why do you think this was
the case?
The sample stored at room temperature for zero hours took the longest time
to turn white.
3. How does refrigeration affect the number of bacteria present in milk?
Refrigeration keeps milk fresh for longer by slowing down the growth of bacteria.
4. How does pasteurization affect the number of bacteria present in milk?
Pasteurization kills bacteria in milk.
