Growth, Nutrition, and Ecology Flashcards Preview

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Flashcards in Growth, Nutrition, and Ecology Deck (61):
1

  • Nutrients and Energy
  • Physical (Environmental) Factors
    • Oxygen
    • Temperature
    • pH
    • Water
    • Salt

Growth Requirements 

2

How does bacteria divide?

Binary fusion 

3

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Binary Fusion

  • Binary fusion is how bacteria divides 
    • Each parent cell leads to two daughter cells

4

–Time required for a bacterial cell to grow and divide

–Dependent on chemical and physical conditions

Generation Time (bacterial growth)

5

–Growth of bacterial populations

–Number of bacteria doubles each generation

–1 to 2 to 4 to 8 to 16, etc.

–20 to 21 to 22 to 23 to 24, etc.

–Exponent is generation number

–2n

Exponential Growth (bacteria)

6

•If you grow a bacterial culture that divides every 30 minutes for a total of 16 hours –

–How many generations have occurred?

–How many more cells will there be after 16 hours?

  • Generations: 
    • 16 hrs x 2 generations = 32 generations
  • Number of cells
    • n = generation
    • 232= 4294967296 bacteria cells 

7

8

How do growth conditions affect generation time and growth?

Generatin time and growth are dependent on chemical and physical conditions

  • Nutrients and Energy

  • Physical (Environmental) Factors

    •Oxygen

    •Temperature

    •pH

    •Water

    •Salt

9

•Pattern of population growth in laboratory samples

•Does not describe populations in nature

•Fundamental for laboratory work, as bacteria behave differently in each phase

Standard Growth Curve

10

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Standard Growth Curve 

•Pattern of population growth in laboratory samples

•Does not describe populations in nature

•Fundamental for laboratory work, as bacteria behave differently in each phase

11

–Little growth, no death

–Bacteria acclimating to new environment

–Cells increase in size, but do not divide

–No change in population size

Lag Phase of Standard Growth Curve

12

–most rapid growth

–exponential increase in population size

–nutrients plentiful, very few waste products in culture

–growth rate >> death rate

–for many experiments, this is ideal time for study

Log Phase of Standard Growth Curve

13

–No change in population size

–growth rate = death rate

–Nutrients are decreasing

–Waste products are increasing

–Sporulation begins here

Stationary Phase of Standard Growth Curve

14

–Numbers of live bacteria in population declines

–Death rate > growth rate

–Nutrients depleted

–Waste products abundant

Death/Decline Phase of Standard Growth Curve

15

•Rely on changes in turbidity in liquid culture

•Do not know number of cells, but can track changes in cell density

•Use spectrophotometer to measure light transmittance through broth

Indirect Method of Measuring Bacterial Growth 

16

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Indirect Method of Measuring Bacterial Growth 

•Rely on changes in turbidity in liquid culture

•Do not know number of cells, but can track changes in cell density

•Use spectrophotometer to measure light transmittance through broth

17

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Indirect Method of Measuring Bacterial Growth

•Rely on changes in turbidity in liquid culture

•Do not know number of cells, but can track changes in cell density

•Use spectrophotometer to measure light transmittance through broth

18

–Count cells on special slide

–Automated cell counters

–Serial dilution and viable plate counts

Direct Method of Measuring Bacterial Growth 

19

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Direct Method of Measuring Bacterial Growth

–Count cells on special slide

–Automated cell counters

–Serial dilution and viable plate counts

20

–Provides estimate of viable cells in original sample

–Dilute sample to produce countable number of colonies on plate

–Mathematically calculate estimate of live cells in sample

–Will explore further in lab

•Serial dilution and viable plate counts for measuring bacterial growth 

21

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•Serial dilution and viable plate counts

–Provides estimate of viable cells in original sample

–Dilute sample to produce countable number of colonies on plate

–Mathematically calculate estimate of live cells in sample

–Will explore further in lab

 

22

–Chemicals that organism needs to synthesize molecules

–C, H, N, O

•Can describe organisms based on how they fulfill these needs

Nutrients

23

•Carbon is basis of all biological molecules

•Heterotrophs

–Acquire carbon from existing organic molecules

•Autotrophs

–Take in carbon as CO2 (inorganic carbon)

Nutrient Acquisition

24

–Acquire carbon from existing organic molecules

•Heterotrophs

25

–Take in carbon as CO2 (inorganic carbon)

•Autotrophs

26

•What is source of energy used by organisms to make ATP?

Energy

27

–Use chemical reactions to acquire energy

•Chemotrophs

28

–Use sunlight to acquire energy

•Phototrophs

29

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30

•What type of molecule is used in energy acquisition for:

Organotroph

•Use organic molecules as energy source

31

•What type of molecule is used in energy acquisition:

–Lithotroph

•Use inorganic molecules as energy source

•Found only in microbes

32

  • Bacteria
    • Nitrosomonas
      • NH3 is electron and energy source
    • Nitrobacter
      • NO2 is electron and energy source
  • Archaea
    • Methanogens
      • H2 is electron and energy source

Lithotrophs

33

•Oxygen

•Temperature

•pH

•Water Activity

•Osmolarity (Salinity)

Physical Requirements

34

•Obligate aerobes

•Obligate anaerobes

•Facultative anaerobes

•Aerotolerant anaerobes

Oxygen Requirements

35

  • Oxygen use and oxygen containing environments produce molecules that can cause damage to biological molecules
    • Superoxide radicals (O2-)
    • Peroxide anions (O2-2)(H2O2)
    • Organisms that tolerate or use oxygen must have mechanisms to deal with these toxic compounds

Oxygen Toxicity

36

  • Require oxygen for metabolism
    • Use aerobic respiration only
  • Are able to detoxify oxygen radicals
    • Possess enzymes to detoxify radicals
    • Superoxide dismutase
    • Catalase
  • Pseudomonas aeruginosa

Obligate Aerobes

37

What are the detoxifying enzymes of obligate aerobes?

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38

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Catalase reaction (detoxifying enzyme of obligate aerobes)

39

  • Do not require or use oxygen
    • Use anaerobic respiration or fermentation
    • DO NOT use aerobic respiration
  • Cannot detoxify oxygen radicals
    • Can only grow in anaerobic environment
  • Clostridium spp.

Obligate anaerobes

40

  • Can use oxygen if present, but do not require it
    • Use aerobic respiration or some type of fermentation
  • Can detoxify oxygen radicals
  • Escherichia coli

Facultative Anaerobes

41

  • Does not use or require molecular oxygen
    • Use anerobic respiration or fermentation
  • Can detoxify oxygen radicals
    • Can grow in aerobic environment
  • Lactobacillus spp.

Aerotolerant Anaerobes

42

Oxygen Requirements

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(a) Obligate aerobes

(b) Obligate aneorobes

(c) Facultative aneorobes

(d) Aerotolerant aneorobes

43

•All organisms adapted to a specific temperature range

•Enzymes and other molecules most stable at these temperatures

Temperature Requirements

44

•Alterations in temperature can have negative effect by: 

–Proteins denature at too high temperature

–Membranes can become too rigid if temperature too cold

–Membranes can melt if temperature too high

45

•Psychrophiles

--5 to < 20 C

46

•Mesophiles

–20 to 45 C

47

•Thermophiles

–45 to < 80 C

48

•Hyperthermophiles

–70 to >100 C

49

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•Psychrophiles (-5 to < 20 C)

•Mesophiles (20 to 45 C)

•Thermophiles (45 to < 80 C)

•Hyperthermophiles (70 to >100 C)

50

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Mesophile (20 to 45 C)

51

Characterisitics of pH for bacteria 

•Amount of H+ and OH- in environment affects hydrogen bonding

•All organisms adapted to specific pH range

•pH too high or too low, can affect proteins and other molecules

52

•Neutrophiles

–Grow best in near neutral conditions

–Near pH 7 optimal 

53

•Alkalinophiles

–Grow best in alkaline conditions

B. subtilis - pH 9-11

54

•Acidophiles

–Grow best under acidic conditions

Acetobacter aceti - pH 2

55

–Liquid (free) water needed to carry out metabolic pathways

–Aw  affected by interaction of water with dissolved substances

–Pure water – 1

–Tap water – 0.99

–Honey, Dried fruit – 0.5 to 0.7

•Water Activity (Aw)

56

What is the Aw requirements of organisms

–Bacteria

•0.95 or greater

57

What are the Aw requirements of organisms:

Fungi

•0.8 or greater

58

What is the Aw requirements for most organisms?

–Most organisms inhibited at 0.5 or below

59

  • Solute concentration in environment affects retention of water
    • Isotonic
    • Hypotonic
    • Hypertonic
  • Salinity often an issue

Osmolarity

60

  • Organisms adapted to increased levels of salinity
  • –Halophiles

–require high salt

61

Organisms adapted to increased levels of salinity

  • –Halotolerant

  • Can live in moderate salt concentrations
    • 1-6% salt to 7-15% salt
  • Skin organisms
    • Staphylococcus aureus