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34 Cards in this Set
- Front
- Back
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The two widely applicable methods of microbial control are... |
moist heat and radiation |
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Minimal time required to kill all microorganisms in liquid suspension at a given temperature? |
thermal death time |
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In the refrigerated incubation experiment for psychotrophic bacteria (grow from 20-40 degrees C but also at 5 degrees, what media was used? |
tryptic soy agar |
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What type of radiation is emitted from ultraviolet light? |
nonionizing radiation |
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how does uv light kill bacteria? |
Damages the chromosomal DNA of exposed cells causing bonds between adjacent thymines (thymine dimer). Effective UV wavelengths are 260nm. |
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How does moist heat kill bacteria? |
Denatures proteins, components of the cell wall, and microbial enzymes. |
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What is an antiseptic? |
Chemical agents used on living things that controls microbe growth. |
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What is a disinfectant? |
Chemical agents used on inanimate objects that control microbe growth. |
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A clear area around a chemical agent placed on the surface of a microbe inoculated media plate is called... |
zone of inhibition. |
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Chemotherapeutic agents used to treat infections are called.. |
antimicrobial agents. |
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Metabolic products of one organism that kill it inhibit the growth of other microbes? |
Antibiotics |
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Media used in Kirby-Bauer Method? |
Mueller Hinton agar (MHA) |
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Method that tests antibiotic susceptibility using filter-paper disks impregnated with known quantities of antimicrobial agent. |
Kirby-Bauer Method |
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Food media that is selective and differential for streptococcus. |
Mitis-Salivarius Agar |
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Food media that is selective and differential for Lactobacillus. |
Tomato Juice Agar |
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Streptococcus that create lactic acid are being reclassified as... |
Lactococcus. |
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Aerobic bacteria that oxidize ethanol into acetic acid (vinegar) and water. |
Acetobacter |
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Dental caries is caused by this bacteria that binds to teeth and creates biofilm for other lactic acid producing bacteria. |
Streptococcus mutans. |
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Agar used for caries susceptibility test. |
Snyder Test agar. Relies on rate in which salivary organisms lower pH in presence of 2% sucrose. Indicator bromcresol green turns yellow of pH falls below certail level after 48 hours. |
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Common method of measuring living cell numbers. |
Standard plate count. |
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Pipets that must have last drop blown out for correctly measured volume. |
"to deliver" |
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Curve of liquid in pipet is called... |
meniscus. |
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Pipet that has one line for transferring a specific amount of liquid. |
Volumetric. |
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Pipets that have markings for multiple volumes. |
Gradated or measuring. |
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Coliforms. |
Gram negative facultative anaerobic, nonspore forming, rod shaped bacteria that ferments lactose with with acid/gas formation within 48hrs at 37 degrees C. |
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Bacteria that is almost always present in feces of animals and humans. |
E. Coli |
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Most Probable Number test |
Represents most probable number of bacteria per 100 mL of water. |
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To confirm presence of coliforms, water samples are inoculated on what media? |
Eosin Methylene Blue Agar. If green metallic sheen with purple colonies are present, positive test for coliforms. |
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Grade A by USDA standards. |
Bacterial numbers must not exceed 20,000 total bacteria/mL and 10 coliforms/mL milk. |
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Tomato Juice Agar with Lactobacillus. Selective factor is low pH. |
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Mitis-Salivarius Agar. Selective for streptococcus. |
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Snyder's Test for susceptibility to dental caries. Bromcresol green turns yellow if acid is produced. |
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What bacteria is used for production of butter, sour cream, buttermilk? |
Streptococcus lactis or Streptococcus cremoris. |
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What bacteria is utilized for yogurt? |
Lactobacillus acidophilus |
