Domanda del libro di testo
How do autoclaving, hot air, and ultra-high-temperature pasteurization illustrate the concept of equivalent treatments?
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Ch. 7 - The Control of Microbial Growth
Tortora14th EditionMicrobiology: An IntroductionISBN: 9780138200398
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TOC.tableOfContents
- Ch. 1 - The Microbial World and You18
- Ch. 2 - Chemical Principles20
- Ch. 3 - Observing Microorganisms Through a Microscope18
- Ch. 7 - The Control of Microbial Growth20
- Ch. 9 - Biotechnology & DNA Technology20
- Ch. 10 - Classification of Microorganisms15
- Ch. 11 - The Prokaryotes: Domains Bacteria and Archaea14
- Ch. 12 - The Eukaryotes: Fungi, Algae, Protozoa, and Helminths17
- Ch. 13 - Viruses, Viroids, and Prions20
- Ch. 14 - Principles of Disease and Epidemiology21
- Ch. 15 - Microbial Mechanisms of Pathogenicity19
- Ch. 16 - Innate Immunity: Nonspecific Defenses of the Host20
- Ch. 17 - Adaptive Immunity: Specific Defenses of the Host20
- Ch. 18 - Practical Applications of Immunology20
- Ch. 19 - Disorders Associated with the Immune System19
- Ch. 20 - Antimicrobial Drugs19
- Ch. 21 - Microbial Diseases of the Skin and Eyes21
- Ch. 22 - Microbial Diseases of the Nervous System19
- Ch. 23 - Microbial Diseases of the Cardiovascular and Lymphatic Systems20
- Ch. 24 - Microbial Diseases of the Respiratory System20
- Ch. 25 - Microbial Diseases of the Digestive System20
- Ch. 26 - Microbial Diseases of the Urinary and Reproductive Systems19
- Ch. 27 - Environmental Microbiology20
- Ch. 28 - Applied and Industrial Microbiology19
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Capitolo 4, Problema 7
How do salts and sugars preserve foods? Why are these considered physical rather than chemical methods of microbial control? Name one food that is preserved with sugar and one preserved with salt. How do you account for the occasional growth of Penicillium mold in jelly, which is 50% sucrose?
Guida verificata passo dopo passo1
Understand that salts and sugars preserve foods primarily by creating a hypertonic environment, which causes water to move out of microbial cells by osmosis, leading to dehydration and inhibition of microbial growth.
Recognize that this preservation method is considered physical rather than chemical because it relies on altering the physical environment (water availability) rather than chemically altering or killing the microbes.
Identify examples of foods preserved by sugar, such as jelly or jam, and foods preserved by salt, such as salted fish or cured meats.
Explain that despite high sugar concentration (e.g., 50% sucrose in jelly), some molds like Penicillium can occasionally grow because they are osmotolerant and can survive in low water activity environments.
Summarize that the effectiveness of salts and sugars depends on their ability to reduce water activity, which is a physical parameter, and that microbial resistance varies among different species.
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Osmotic Pressure and Microbial Preservation
Salts and sugars preserve food by creating a hypertonic environment that draws water out of microbial cells through osmosis, leading to dehydration and inhibition of microbial growth. This reduction in available water prevents spoilage and extends shelf life without directly killing microbes.
Video consigliato:
02:37
High Pressure Processing
Physical vs. Chemical Methods of Microbial Control
Physical methods inhibit microbial growth by altering environmental conditions, such as water availability, temperature, or radiation, without chemically altering microbial structures. In contrast, chemical methods involve substances that react with microbial components to kill or inhibit them. Salting and sugaring are physical because they rely on osmotic effects rather than chemical reactions.
Video consigliato:
01:46Physical Methods to Control Microbial Growth
Microbial Growth in High Sugar or Salt Environments
Despite high sugar or salt concentrations, some microbes like Penicillium molds can occasionally grow due to their ability to tolerate lower water activity or form resistant spores. In jelly with 50% sucrose, Penicillium can survive by exploiting microenvironments or slight variations in sugar concentration, leading to spoilage.
Video consigliato:
06:30Osmolarity Factors for Microbial Growth
Pratica correlata
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A large hospital washes burn patients in a stainless steel tub. After each patient, the tub is cleaned with a quat. It was noticed that 14 of 20 burn patients acquired Pseudomonas infections after being bathed. Provide an explanation for this high rate of infection.
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Domanda del libro di testo
Use the following information to answer questions 6 and 7. The data were obtained from a use-dilution test comparing four disinfectants against Salmonella Choleraesuis.
G = growth, NG = no growth
Which disinfectant is the most effective?
916
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Domanda del libro di testo
Which of the following is not a characteristic of quaternary ammonium compounds?
a. Bactericidal against gram-positive bacteria
b. Sporicidal
c. Amebicidal
d. Fungicidal
e. Kills enveloped viruses
1032
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Domanda del libro di testo
The use-dilution values for two disinfectants tested under the same conditions are as follows:
Disinfectant A—1:2
Disinfectant B—1:10,000.
If both disinfectants are designed for the same purpose, which would you select?
66
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Domanda del libro di testo
Use the following information to answer questions 6 and 7. The data were obtained from a use-dilution test comparing four disinfectants against Salmonella Choleraesuis.
G = growth, NG = no growth
Which disinfectant(s) is (are) bactericidal?
a. A,B,C, and D
b. A,C, and D
c. A only
d. B only
e. None of the above
682
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