Textbook Question
A student observes a researcher streaking a plate numerous times, flaming the loop between streaks. The researcher is likely using the ___________ method to isolate microorganisms.
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Ch. 6 - Microbial Nutrition and Growth
Bauman6th EditionMicrobiology with Diseases by TaxonomyISBN: 9780134832302
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Table of contents
- Ch. 1 - A Brief History of Microbiology31
- Ch. 2 - The Chemistry of Microbiology28
- Ch. 3 - Cell Structure and Function39
- Ch. 4 - Microscopy, Staining, and Classification25
- Ch. 5 - Microbial Metabolism51
- Ch. 6 - Microbial Nutrition and Growth37
- Ch. 7 - Microbial Genetics51
- Ch. 8 - Recombinant DNA Technology21
- Ch. 9 - Controlling Microbial Growth in the Environment36
- Ch. 10 - Controlling Microbial Growth in the Body: Antimicrobial Drugs21
- Ch. 11 - Characterizing and Classifying Prokaryotes29
- Ch. 12 - Characterizing and Classifying Eukaryotes34
- Ch. 13 - Characterizing and Classifying Viruses, Viroids, and Prions23
- Ch. 14 - Infection, Infectious Diseases, and Epidemiology35
- Ch. 15 - Innate Immunity34
- Ch. 16 - Adaptive Immunity21
- Ch. 17 - Immunization and Immune Testing29
- Ch. 18 - Immune Disorders22
- Ch. 19 - Pathogenic Gram-Positive Bacteria25
- Ch. 20 - Pathogenic Gram-Negative Cocci and Bacilli28
- Ch. 21 - Rickettsias, Chlamydias, Spirochetes, and Vibrios25
- Ch. 22 - Pathogenic Fungi47
- Ch. 23 - Parasitic Protozoa, Helminths, and Arthropod Vectors44
- Ch. 24 - Pathogenic DNA Viruses23
- Ch. 25 - Pathogenic RNA Viruses30
- Ch. 26 - Applied and Industrial Microbiology29
- Ch. 27 - Microbial Ecology and Microbiomes22
Bauman6th EditionMicrobiology with Diseases by TaxonomyISBN: 9780134832302Not the one you use?Change textbook
Chapter 6, Problem 12
Which of the following methods is best for counting fecal bacteria from a stream to determine the safety of the water for drinking?
a. Dry weight
b. Turbidity
c. Viable plate counts
d. Membrane filtration
Verified step by step guidance1
Understand the goal: We want to count fecal bacteria in a water sample to assess its safety for drinking. This requires a method that accurately detects and quantifies bacteria, especially those indicating fecal contamination.
Evaluate each method: Dry weight measures the total biomass of microorganisms but does not differentiate fecal bacteria specifically, so it is not ideal for this purpose.
Turbidity measures cloudiness of water caused by particles, including bacteria, but it is not specific and cannot distinguish fecal bacteria from other particles or microbes.
Viable plate counts involve spreading a diluted water sample on agar plates and counting colonies that grow, which gives a count of live bacteria but can be time-consuming and may not be selective for fecal bacteria.
Membrane filtration involves filtering a known volume of water through a membrane that traps bacteria, then placing the membrane on selective media to grow and count fecal bacteria colonies. This method is sensitive, specific, and widely used for water safety testing.
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Fecal Bacteria as Water Contaminants
Fecal bacteria, such as Escherichia coli, indicate contamination by fecal matter and potential presence of pathogens. Monitoring their levels in water helps assess safety for drinking, as high counts suggest health risks from waterborne diseases.
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Introduction to Water
Viable Plate Counts
Viable plate counts involve spreading a water sample on nutrient agar to grow and count live bacterial colonies. This method estimates the number of living bacteria but can be time-consuming and may underestimate bacteria that do not grow well on plates.
Recommended video:
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01:36Measuring Growth by Plate Counts
Membrane Filtration Technique
Membrane filtration captures bacteria on a filter, which is then placed on selective media to grow colonies. It is highly effective for detecting and quantifying fecal bacteria in water, allowing for accurate and rapid assessment of water safety.
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02:29Measuring Growth by Membrane Filtration
Related Practice
Textbook Question
Lyophilization can be described as:
a. Freeze-drying
b. Deep-freezing
c. Refrigeration
d. Pickling
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Textbook Question
Chemolithotrophs acquire electrons from (organic/inorganic)___________ compounds.
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Textbook Question
A Coulter counter is a(n):
a. Statistical estimation using 15 dilution tubes and a table of numbers to estimate the number of bacteria per milliliter
b. Indirect method of counting microorganisms
c. Device that directly counts microbes as they pass through a tube in front of an electronic detector
d. Device that directly counts microbes that are differentially stained with fluorescent dyes
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Textbook Question
How does a chemostat maintain a constant population size?
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Textbook Question
Which of the following is most useful in representing population growth on a graph?
a. Logarithmic reproduction of the growth curve
b. A semilogarithmic graph using a log scale on the y-axis
c. An arithmetic graph of the lag phase followed by a logarithmic section for the log, stationary, and death phases
d. None of the above would best represent a population growth curve
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