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Microbiology > Chapter 7: Fundamentals of Microbial Growth > Flashcards

Chapter 7: Fundamentals of Microbial Growth Flashcards

(58 cards)

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1
Q

Define: Binary Fission

A

-occurs in most prokaryotes -involves dividing a single cell into two cells -asexual process

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2
Q

Define: Budding

A

-asexual reproduction -original cell elongates and forms small outgrowth on one side -chromosome is duplicated and placed in the bud -separation from the mother cell occurs

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3
Q

Define: Spore Formation

A

-performed by some fungi and bacteria -asexual or sexual in fungi -asexual in bacteria ex.) streptomyces-forms spores that hang off of long hyphae extensions

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4
Q

Define: Generation Time

A
  • the time it takes for a cell to divide -interval of time between successive binary fissions
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5
Q

Define: Exponential Growth

A

-basically means doubling in amount each generation time *Generation Time (in minutes)= Growth time (in minutes)/Number of Generations

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6
Q

Define: Maximum, Minimum, and Optimal Temp.

A

Maximum-highest temp. that supports growth

Minimum- lowest temp. that supports growth

Optimal- temp. where cellular growth is highest

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7
Q

Define: Heterotroph

A

-requires external source of organic carbon (sugars, lipids, proteins)

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8
Q

Define: Autotroph

A

-do not require an external source of organic carbon (make their own food)

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9
Q

Define: Fastidious

A

-organisms that need multiple growth factors

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10
Q

Define: Phototroph

A
  • organisms that use light energy
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11
Q

Define: Chemotroph

A

-organisms that break down chemical compounds for energy

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12
Q

Define: Defined Media

A
  • chemically defined or precisely know composition
  • each inorganic and organic component is completely known and quantified
  • useful for growing certain autotrophs and heterotrophs
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13
Q

Define: Complex Media

A
  • contains a mixture of organic and inorganic nutrients that are not fully defined
  • contain more complex ingredients (blood, milk, proteins, extracts, etc.)
  • used to grow fastidious organisms with complex growth requirements
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14
Q

Define: Differential Media

A

-media formulated to visually distinguish one microbe from another

blood agar

Beta Hemolytic: breaks down red blood cells

Alpha Hemolytic: partial break down of red blood cells

Gamma Hemolytic: do not lyse red blood cells

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15
Q

Define: Selective Media

A
  • single out bacteria that have specific properties
  • ingredients foster the growth of certain bacteria and suppress the growth of others
    ex. ) Mannitol salt agar- differentiates organisms based on ability to ferment mannitol

Eosin methylene blue agar- limits gram + bacterial growth/differentiates based on ability to ferment lactose

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16
Q

Define: Streak Plate

A
  • isolates bacteria in a mixed culture
  • bacteria spread out over 4 quadrants
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17
Q

Factors That Influence Microbial Growth

A
  • Temp.
  • pH
  • Salt
  • Oxygen
  • Carbon Dioxide
  • Nutrients/Growth Factors
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18
Q

Define: Extreme Thermophile

A
  • grow around 65-120 degrees C
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19
Q

Define: Thermophile

A
  • grow around 40-75 degrees C
  • associated with compost piles and hot springs
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20
Q

Define: Mesophiles

A
  • grow best around 10-50 degrees C
  • associated with most pathogens
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21
Q

Define: Psychrotrophs

A
  • grow at 0-30 degrees C
  • associated with foodborne illness
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22
Q

Define: Psychrotolerant

A

-prefer to grow at 37 degrees but can grow at refrigeration temperatures (food poisoning)

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23
Q

Define: Psychrophile

A

-thrive between -20 degress C and 10 degrees C

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24
Q

Define: Barophile

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A

-can withstand the high pressure environment of the deep sea

25
Define: Acidophile
- grow at a pH of 1-5 - live in sulfur hot springs/volcanic vents - maintain fairly neutral cytoplasmic pH - use proton pumps
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Define: Neutralophiles
- grow at a pH range of 5-8 - make up majority of microorganisms
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Define: Alkaliphile
- grow in basic pH of 9-11 - associated with soda lakes
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Define: Halophile
- thrive in high salt environments - tolerate up to 35%
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Define: Facultative Halophile
- tolerate higher salt environments ex. ) staphylococcus aureus
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Define: Extremophile
-organisms that live in extremes of pH, temperature, and/or salt
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Define: Aerobe
-detoxify ROS (reactive oxygen species) so they can safely use oxygen in their metabolism
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Define: Anaerobe
- do not use oxygen in their metabolic processes
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Define: Obligate Anaerobe
- do not use ROS in their metabolism - cannot eliminate ROS - die in aerobic environments
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Define: Obligate Aerobes
- absolute dependence on oxygen for cellular processes - will die unless oxygen is abundant
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Define: Microaerophile
- use small amounts of oxygen - live in low oxygen settings
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Define: Facultative Anaerobe
- grow with and without oxygen - switch between using oxygen and fermentation
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Define: Aerotolerant Anaerobe
- tolerate oxygen but dont use it - have ways to deactivate ROS
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Phases of Bacteria Growth Curve
Lag Phase: no cell division/ bacteria adapt to their new environment Log Phase: exponential growth of the population occurs/ human disease symptoms develop Stationary Phase: reproductive and death rates are equal Death Phase: accumulation of waste products and lack of resources causes population to die
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Media
Liquid Media (broth)- ideal for growing large batches of microbes Solid Media (agar)- useful for isolating colonies and observing specific culture characteristics Semisolid Media(deep)- useful for motility testing
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Techniques used for counting microbes (Direct Methods)
Coulter Counter: machine that counts number of cells as they pass through a thin tube (cells both living and dead are counted) Flow Cytometer: uses a laser light to detect cells passing through a narrow channel/cells are fluorescently labeled (differentiates between living and dead cells) Viable Plate Count: direct enumeration of bacteria using agar plates/samples are serially diluted
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Techniques used for counting microbes (Indirect Methods)
Turbidity: more cells=cloudier (more turbid) /uses spectrophotometer to measure transmission or absorbance of light - assessing total dry weight - detecting metabolic activity in a sample (CO2 production and oxygen use)
42
Define: Pasteurization
- application of moderate heat that eliminates pathogens and reduces harmless microbes that cause milk spoilage
43
Define: Boiling
- boiling water for 5 minutes eliminates most pathogenic bacteria, protozoans, and viruses - endospores can withstand hours of boiling
44
Define: Dry Heat
- incineration or hot-air ovens used for sterilization or disinfection ex. ) heating an inoculation loop
45
Define: Ionizing Radiation
- Gamma rays and X-rays - generate reactive ions that kill microbes and inactivate viruses - damage nucleic acids
46
Define: Non-Ionizing Radiation
- Ultraviolet (UV) rays - causes thymine dimers - alter structure of DNA leading to mutation
47
Define: Filtration
- large volumes of liquid or air can be passed through microbe-capturing filters ex. ) HEPA filters
48
Define: germicides
- chemicals that control microbial growth low level-destroy bacteria, fungi, and some viruses intermediate level-destroy all bacteria including viruses, but not endospores high level- destroy all microbes and endospores
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Define: disinfectant
-used to treat inanimate objects
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Define:Antiseptics
-applied to living tissues
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Define: microbiocidal
-germicides that kill microbes
52
Define: microbiostatic
-germicides that only inhibit microbial growth
53
Critical, Semicritical, and Noncritical equipment
Critical equipment: comes into contact with sterile body sites or the vascular system; must be sterilized Semicritical equipment: comes in contact with mucous membranes or non-intact skin/should be free of bacteria, fungi, and viruses with low numbers of endospores Noncritical equipment: contact patients' intact skin/requires less stringent disinfection
54
Define: Thermal Death Time
- shortest period of time at a certain temperature needed to kill all microbes in a sample
55
Define: Thermal Death Point
-minimum temperature needed to kill all microbes in a sample within 10 minutes
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Specific methods of control
Mycobacterium control-cause tuberculosis and leprosy/have cell walls rich in mycolic acid Endospore control- bacillus and clostridium/ use autoclaving to eliminate endospores Viral control-use heat, drying, and detergents Protozoan control- filtration/UV light Prion control- eliminated through combination of chemical treatments and increased temperature adn pressure during autoclaving

Microbiology (10 decks)

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