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HLSC 124 - Microbiology for Health Professionals > Chapter 6 - Microbial Growth > Flashcards

Chapter 6 - Microbial Growth Flashcards

1
Q

Physical Requirements for Growth

A

-temperature
-pH
-osmotic pressure

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2
Q

Chemical Requirements for Growth

A

-sources of carbon, nitrogen, sulfur, phosphorus, oxygen
-trace elements
-organic growth factors

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3
Q

True Psychrophiles

A

-cold-loving microbes
-can grow at 0℃
-optimum: 15℃
-cannot grow in reasonably warm room (20-25℃)
-non-pathogenic (don’t cause diseases)
-ie. bacteria in antarctica or ocean depth

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4
Q

Psychrotrophs (Psychrophile group)

A

-aka facultative/flexible
-more common than psychrophile
-can grow at 0℃
-optimum: 20-30℃
-cannot grow: 30℃+
-pathogenic: food spoilage (usually in the fridge)
-ie. mold, odour, slime layer

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5
Q

Mesophiles

A

-moderate-temp-loving microbes
-grow at a large range: 35-40℃
-optimum: 37℃ (human body temp)
-cannot grow: 50℃+
-all pathogenic: common spoilage and disease organisms

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6
Q

Thermophiles

A

-heat-loving microbes
-cannot grow below 45℃
-optimum: 50-60℃ (hot water)
-max: 70-80℃

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7
Q

Hyperthermophiles (Thermophile group)

A

-max temp: 110℃ (boiling water)
-optimum temp: 80℃+
-deep sea thermal vents or volcanoes

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8
Q

Minimum Growth Temperature

A

-lowest temp at which the species will grow

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9
Q

Optimum Growth Temperature

A

-temp at which the species grows best

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10
Q

Maximum Growth Temperature

A

-highest temp at which growth is possible

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11
Q

pH

A

-most bacteria grow best between 6.5 and 7.5
-few grow below 4 (acidic)

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12
Q

Acidophiles

A

-tolerant of acidity

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13
Q

Osmotic Pressure

A

-microbes require water for growth

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14
Q

Hypertonic

A

-concentration of solutes is higher outside the cell (environment is hypertonic to the cell)
-cellular water passes into high solute concentration
-cells cytoplasm shrinks (plasmolysis)

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15
Q

Extreme Halophiles

A

-adapted to high salt concentrations so they require them for growth

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16
Q

Facultative Halophiles

A

-do not require high salt concentration but can tolerate up to 2%

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17
Q

Isotonic

A

-same concentration of salt and water

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18
Q

Hypotonic

A

-osmotic pressure is unusually low
-water will enter cell

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19
Q

Carbon

A

-one of the most important requirements for microbial growth

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20
Q

Oxygen

A

-not essential for bacterial life
-divides bacteria into 5 groups

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21
Q

Obligate Aerobes

A

-need O₂ to complete ETC and survive
-love oxygen
-extract more energy (ATP)
-most bacteria belong to this group
-grow well
-produce SOD and catalase

22
Q

Facultative Anaerobes

A

-flexible
-use O₂ for growth and metabolism when available
-when O₂ not available: goes into anaerobic cell resp or fermentation and growth is slowed
-create a variable # of ATP
-produce SOD and catalase
-ie. Escherichia Coli

23
Q

Obligate Anaerobes

A

-unable to use O₂
-harmed by O₂
-undergo glycolysis but not krebs cycle or ETC
-ie. Clostridium
-NO SOD OR CATALASE

24
Q

Aerotolerant Anaerobes

A

-tolerate O₂
-fermentative and can’t use O₂ for growth/metabolism
-ie. Lactobacilli
-can tolerate O₂ because they have SOD and catalase

25
Q

Microaerophiles

A

-aerobic (require O₂)
-grow only in O₂ concentrations lower than the air
-ie. Helicobacter pylori, Campylobacter jejuni

26
Q

Helicobacter pylori

A

-causes stomach ulcers

27
Q

Campylobacter jejuni

A

-GI issues
-diarrhea and cramping

28
Q

Toxic Oxygen

A

-O₂ starts to generate toxic forms during metabolism

29
Q

Singlet Oxygen

A

-normal O₂ that has been boosted to a high energy state ¹O₂⁻
-extremely reactive

30
Q

Superoxide Radicals

A

-O₂⁻ is formed in small amounts during normal aerobic respiration
-steal electrons from other molecules

31
Q

Superoxide Dismutase (SOD)

A

-an enzyme formed by some organisms attempting to grow in atmospheric O₂
-neutralizes toxic O₂⁻ by converting it into O₂ and hydrogen peroxide (H₂O₂)

32
Q

Peroxide Anion

A

-O₂²⁻
-produced from the hydrogen peroxide produced in the SOD reaction
-is toxic because it steals from other dangerous molecules

33
Q

Catalase

A

-enzyme used to neutralize the peroxide anion
-converts it to water and oxygen

34
Q

Perioxidase

A

-another enzyme that breaks down hydrogen peroxide
-reaction doesn’t produce oxygen

35
Q

Hydroxyl Radical

A

-OH﹒
-most reactive intermediate form of oxygen
-no enzyme that can neutralize
-irreversible

36
Q

Biofilms

A

-communities of bacteria
-thin slimy layer encasing bacteria that adheres to a surface
-biological systems
-how infection can spread

37
Q

Quorum Sensing

A

-cell-to-cell communication
-coordinate activities

38
Q

Culture Medium

A

-nutrients prepared for microbial growth

39
Q

Inoculum

A

-introduction of microbes to a medium

40
Q

Culture

A

microbes growing in (nutrient broth) or on (agar plate) a medium

41
Q

Sterile

A

-medium must be sterile and contain no other microorganisms

42
Q

Agar

A

-complex polysaccharide
-remains solid and sterile
-not metabolized by many microorganisms
-liquifies at 100℃
-cool down to 45℃
-incubate at 37℃

43
Q

Pure Culture

A

-contains only one species or strain
-streak plate method used to isolate cultures

44
Q

Colony

A

-population of cells arising from a single cell or spore

45
Q

Streak Method

A

-divide petri dish into thirds
-move clockwise and dip some in each section

46
Q

Selective Media

A

-used to suppress unwanted microbes and encourage desired microbes
-Bismuth sulfite agar
-ie. growing Salmonella typhus (causes typhoid fever and GI tract hemorrhaging disease)

47
Q

Differential Media

A

-make it easy to distinguish colonies if different microbes
-uses blood agar
-a clear ring/empty region will appear around the colonies where hemolysis of the RBCs has occured
-ie. to grow Steptococcus pyogenes (causes strep throat)

48
Q

Selective and Differential Media

A

-suppress unwanted organisms
-make it easy to distinguish colonies
-mannitol salt agar
-yellow halo that degraded the mannitol occurs
-ie. Staphylococcus aureus (skin infections, TSS, food poisioning)

49
Q

Binary Fission

A

-increase in numbers, not size
-cells divide and grow exponentially

50
Q

Bacterial Growth Curve

A
  1. LAG PHASE: intense activity preparing for growth but no increase in population
  2. LOG PHASE: exponential population increase, best time to give antibiotics/use radiation
  3. STATIONARY PHASE: plateau, equilibrium, deaths balance new growth
  4. DEATH PHASE: population decreases at a logarithmic rate
51
Q

Generation Time

A

-time required for a cell to divide (population to double)
-time (in minutes)/number of generations

HLSC 124 - Microbiology for Health Professionals (18 decks)

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