Lab 6 Food Microbiology BIO250L
Student Name:
Access Code (located on the underside of the lid of your lab kit): Click here to enter text.
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?
Harmful E. coli that are in polluted food and water are a straine of E.coli called
Enterohemorrhagic strains. Harmless strains are part of the normal microflora of
the gut. These benefit the host by producing vitamin K. Without these harmless
strains we would not be able to produce vitamin Kand would have to depend on
supplements.
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.
Yogurt- Lactobacillus, Milk- Listeris monocytogenes, Cheese- Lactococcus,
Lactobacillus, and Streptococcus families, Breead- Saccharomyces cerevisiae,
Frute- E.coil.
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 are 10 timmes more likely to catch Listeria monocytogenes
than other people. Listeria monocytogenes can cause
, Lab 6 Food Microbiology BIO250L
miscarriage, still birth, and pre-term labor in pregnant women. In newborn’sit can
cause serious illness and death.
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 2:00 PM 3/8/19 5:30 PM 3/8/19 3.5 Hours
1 hour 2:01 PM 3/8/19 4:20 PM 3/8/19 2 Hours 19 Minutes
3 hours 2:02 PM 3/8/19 3:30 PM 3/8/19 1 Hour 28 Minutes
4 hours 2:03 PM 3/8/19 2:55 PMM 3/8/19 52 Minutes
Post-Lab Questions
1. On average, which sample took the least time to become white? Why do you think this was the
case?
The 4- hour sample took the least amount of time to become white. We think it
did because the milk had less oxygen in it since it had been sittingout.
2. On average, which sample took the most time to become white? Why do you think this was the
case?
The 0- hour sample took the most time to become white. We think it didbecause it
had more oxygen since it hadn’t been sitting out very long.
Student Name:
Access Code (located on the underside of the lid of your lab kit): Click here to enter text.
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?
Harmful E. coli that are in polluted food and water are a straine of E.coli called
Enterohemorrhagic strains. Harmless strains are part of the normal microflora of
the gut. These benefit the host by producing vitamin K. Without these harmless
strains we would not be able to produce vitamin Kand would have to depend on
supplements.
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.
Yogurt- Lactobacillus, Milk- Listeris monocytogenes, Cheese- Lactococcus,
Lactobacillus, and Streptococcus families, Breead- Saccharomyces cerevisiae,
Frute- E.coil.
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 are 10 timmes more likely to catch Listeria monocytogenes
than other people. Listeria monocytogenes can cause
, Lab 6 Food Microbiology BIO250L
miscarriage, still birth, and pre-term labor in pregnant women. In newborn’sit can
cause serious illness and death.
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 2:00 PM 3/8/19 5:30 PM 3/8/19 3.5 Hours
1 hour 2:01 PM 3/8/19 4:20 PM 3/8/19 2 Hours 19 Minutes
3 hours 2:02 PM 3/8/19 3:30 PM 3/8/19 1 Hour 28 Minutes
4 hours 2:03 PM 3/8/19 2:55 PMM 3/8/19 52 Minutes
Post-Lab Questions
1. On average, which sample took the least time to become white? Why do you think this was the
case?
The 4- hour sample took the least amount of time to become white. We think it
did because the milk had less oxygen in it since it had been sittingout.
2. On average, which sample took the most time to become white? Why do you think this was the
case?
The 0- hour sample took the most time to become white. We think it didbecause it
had more oxygen since it hadn’t been sitting out very long.
