Laboratory Experiments in Microbiology (12th Edition) (What's New in Microbiology)
12th Edition
ISBN: 9780134605203
Author: Ted R. Johnson, Christine L. Case
Publisher: PEARSON
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Chapter 26, Problem 1CA
The following data were collected from soaps after 1 week of use at a hospital nurses’ handwashing station. Neither bacteria nor fungi were isolated from any of the products before use. Aerobic bacteria were isolated from 25 soap products. Data are expressed as percentage of soap products contaminated.
What conclusions can you draw from these data?
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The following data were obtained from pour plates used to test the effectiveness of a food preservative. Two samples of cottage cheese were inoculated with bacteria; the preservative was added to one sample. After incubation, samples of the cottage cheese (control) and samples treated with the preservative (experimental) were diluted and plated on nutrient agar. Calculate the number of bacteria. Was the preservative effective?
Dilution
Amount Plated (mL)
Number of Colonies
CFU/mL
Control
1:400
1
160
Experimental
1:200
0.1
32
The number of bacteria in saliva samples was determined by collecting the saliva, making serial dilutions, and inoculating nutrient agar by the pour plate method. The plates were inoculated aerobically for 48 hours at 37°C.
What can you conclude from this data? Why?
Mouthwash
CFU per ml in salvia
Before Use After Use
Listerine
2.22 x 107 1.22x107
Schmidts Mouthwash
2.42 x 107 3.22x105
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3.21 x 107 2.12 x106
You must write up your OWN dichotomous key for all the possible unknown organisms listed below. The first step of the key will be the Gram Stain and the second will be Gram negative. Subsequent steps will include biochemical tests only.
Solve the identity of an unknown bacterial specimen by creating a dichotomous key and using the staining, culturing and biochemical identification procedures .
Possible Organisms
Alcaligenes faecalis
Enterobacter aerogenes
Enterococcus faecalis
Escherichia coli
Proteus vulgaris
Pseudomonas aeruginosa
Salmonella arizoniae
Staphylococcus aureus
Staphylococcus epidermidis
Staphylococcus saprophyticus
Streptococcusbovis
Streptococcus pyogenes.
Can you please help me find the dichotomous key .
Thank you !
Chapter 26 Solutions
Laboratory Experiments in Microbiology (12th Edition) (What's New in Microbiology)
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