Elements of Microbial Nutrition, Ecology and Growth

1

• Elements of Microbial Nutrition, Ecology and
  Growth
• Chapter 7

2
Microbial nutrition

• ____________ process by which chemicals
  (nutrients) are acquired from environment and
  used by organism
• ________________________ must be provided can
  be in elemental or molecular form
• Elements needed for life ________________ Ca Fe
  Na Cl Mg and some others

3
Nutrients
Microbial nutrition

• ____________ required in large quantities
  principal roles in cell structure metabolism
• proteins, carbohydrates
• ____________or trace elements required in small
  amounts involved in enzyme function
  maintenance of protein structure
• manganese, zinc, nickel

4
Nutrients
Microbial nutrition

• ____________nutrients atom or molecule that
  contains a combination of atoms other than carbon
  and hydrogen
• metals and their salts (magnesium sulfate, ferric
  nitrate, sodium phosphate), gases (oxygen, carbon
  dioxide) and water
• ____________nutrients- contain ____________and
  ____________atoms and are usually the products of
  living things
• methane (CH4), carbohydrates, lipids, proteins,
  and nucleic acids

5
(No Transcript)
6
Microbial nutrition
7
Chemical composition of cytoplasm
Microbial nutrition

• 70 water
• proteins
• 96 of cell is composed of 6 elements
• ____________
• ____________
• ____________
• ____________
• ____________

See Table 7.2 for E. coli
8
8
9
How do organisms obtain carbon?
Microbial nutrition
- 6 major elements

• ____________ an organism that must obtain carbon
  in an organic form made by other living organisms
  (proteins, carbohydrates, lipids and nucleic
  acids)
• ____________- an organism that uses CO2, an
  inorganic gas as its carbon source
• not dependent on other living things

10
Nitrogen
6 major elements

• Main reservoir is nitrogen gas (N2)
• 79 of earths atmosphere is N2
• Nitrogen is part of the structure of proteins,
  DNA, RNA ATP these are the primary source of
  N for heterotrophs
• Some bacteria algae use inorganic N nutrients
  (NO3-, NO2-, or NH3)
• Some bacteria can fix N2
• Regardless of how N enters the cell, it must be
  converted to NH3, the only form that can be
  combined with carbon to synthesis amino acids,
  etc.

11
Oxygen
6 major elements

• O2 makes up ______ of atmosphere
• essential to metabolism of many organisms
• major component of carbohydrates, lipids and
  proteins
• plays an important role in structural enzymatic
  functions of cell
• component of inorganic salts (sulfates,
  phosphates, nitrates) water

12
Hydrogen
6 major elements

• major element in all organic compounds several
  inorganic ones (water, salts gases)
• gases are produced used by microbes
• roles of hydrogen
• maintaining ________
• forming H bonds between molecules
• serving as the source of free energy in
  oxidation-reduction reactions of respiration

13
Phosphorous
6 major elements

• main inorganic source is phosphate (PO4-3)
  derived from phosphoric acid (H3PO4) found in
  rocks oceanic mineral deposits
• key component of ____________, essential to
  genetics
• serves in energy transfers (ATP)

14
Sulfur
6 major elements

• widely distributed in environment rocks,
  sediments contain sulfate, sulfides, hydrogen
  sulfide gas and sulfur
• essential component of some vitamins and the
  amino acids methionine cysteine
• contributes to stability of proteins by forming
  disulfide bonds

15
Important mineral ions

• Potassium
• Sodium
• Calcium
• Magnesium
• Iron

16
Growth factors

• organic compounds that cannot be synthesized by
  an organism must be provided as a nutrient
  (essential ____________ nutrient)
• essential amino acids 20 obtained from food
• vitamins

17
How microbes feed

• Nutritional type is based carbon and energy
  sources
• Example
• ____________ use inorganic carbon (CO2)
• Photoautotrophs make their own energy using
  light (photo)
• Chemoautotrophs Make their own energy using
  chemicals rather than light

18
terminology
How microbes feed

• Prefixes
• Troph- food, nourishment
• Auto- self
• Hetero- other
• Photo- light
• Sapro- rotten
• Halo- salt
• Thermo- heat
• Psychro- cold
• Aero- air (O2)

• Suffixes
• -phile to love
• -obe to live
• -troph food

• examples
• Autotroph
• Chemoautotroph
• Halophile, thermophile
• Aerobe, saprobe
• Aerophile (aerophilic)

19
Facultative vs. obligate
How microbes feed

• ____________ organism is able to adapt to a wide
  range of metabolic conditions therefore it can
  facultatively switch its niche, habitat,
  nutrition etc.
• ____________or strict has a narrow niche,
  habitat due to limitations in its nutrition or
  metabolism. Microbe can only grow under those
  conditions.

20
? PRINT FULL SIZE
How microbes feed
Carbon source Energy source
photoautotrophs CO2 ____________
chemoautotrophs CO2 Simple inorganic ____________
photoheterotrophs organic ____________
chemoheterotrophs organic Metabolizing organic ____________
21
examples
How microbes feed

• ____________
• Photoautotrophs photosynthesis
• 6CO2 12H2O light energy ? C6H12O6 6O2
  6H2O
• Chemoautotrophs methanogens
• 4H2 CO2 ? CH4 2H2O
• ____________
• Chemoheterotrophs
• C6H12O6 6O2 ? 6CO2 6H2O energy

22
How microbes feed

• ____________ decompose dead organisms, recycle
  elements, release enzymes to digest materials
• ____________ utilize tissues and fluids of a
  living host and cause harm
• parasites and saprobes can be facultative
  (opportunistic pathogen) or obligate

23
saprobes
How microbes feed

• Cannot engulf large particles of food
• Substrate is digested _________ by secreted
  enzymes
• Small molecules are transported into cell

24
How microbes feed
24
25
Symbiosis
How microbes live

• Means ________________________
• Organisms (____________) have close association
• ____________obligatory, both symbionts benefit
• Termite gut flagellates
• ____________commensal receives benefit, symbiont
  (host) is neither harmed nor benefited
• satellitism, commensal intestinal bacteria
  (normal microbial flora)
• ____________ parasite benefits, host is harmed
• Intestinal helminths, Rickettsia, all viruses

26
Non-symbiotic microbial associations
How microbes live

• organisms are free-living relationships not
  required for survival
• ____________ members cooperate and share
  nutrients
• ____________ some members are inhibited or
  destroyed by others

27
Ecological Associations Among Microorganisms
27
28
Interrelationships Between Microbes and Humans

• Human body is a rich habitat for symbiotic
  bacteria, fungi, and a few protozoa - normal
  microbial ____________
• Commensal, parasitic, and synergistic
  relationships

28
29
Microbial Biofilms

• ____________result when organisms attach to a
  substrate by some form of extracellular matrix
  that binds them together in complex organized
  layers
• Dominate the structure of most natural
  environments on earth
• Communicate and cooperate in the formation and
  function of biofilms quorum sensing

29
30
Figure 7.13
30
31
How do microbes get their nutrients??What are
the transport mechanisms used to import nutrients
and export waste?
REMEMBER Transport occurs across the
________________________even in microbes with
cell walls, all that is going in or coming out
must cross the cell membrane
32
transport mechanisms

1. ____________ require no energy input from cell
   (uses laws of physics, like entropy)
2. ____________ require energy input from cell

33
Transport mechanisms

• Passive transport do not require energy,
  substances exist in a gradient and move from
  areas of higher concentration towards areas of
  lower concentration
• ____________
• ____________ diffusion of water
• ________________________ requires a carrier

34
concentration

• Amount solute/solvent
• Solute can be solid, liquid, gas
• Solvent is usually liquid
• Percentage ________________________
• Examples 3 NaCl 3 g in 100 mL 0.3 g/L
• Molarity ________________________
• Examples 1 M NaCl solution, 10 M glucose
  solution etc.
• Tonicity ____________gt ____________in terms of
  amount of solute. ____________means both
  solutions have the same amount of solute.
• Examples
• 10 NaCl is more hypertonic than 1 NaCl
• 1 M glucose is more hypotonic than 5 M glucose

35
diffusion

• Molecules move along gradient
• High ? low concentration
• Due to RANDOM motion increased by heat
  (entropy)
• Evidence Brownian movement

36
Diffusion in cells
Passive transport

• Small, nonpolar molecules can diffuse across cell
  membrane (oxygen, small lipids)
• Polar molecules ____________ ___________________
  _____ (facilitated diffusion still PASSIVE
  transport using energy of gradient)

37
Facilitated diffusion
Passive transport

• Carrier proteins embedded in membrane
• Specific for a single type of molecule
• Saturation can occur (all binding sites on
  carrier proteins are occupied by molecule being
  transported)
• Competition similar molecules can compete for
  binding sites one with higher affinity (or
  concentration) will win and be transported

38
Facilitated diffusion
38
39
osmosis

• ________________________ ________________________
  (therefore SOLUTE cannot diffuse so water
  moves instead)
• WATER moves from High ? low water conc.
  (essentially, water moves from low SOLUTE to high
  SOLUTE)
• Water moves from ______________________________
• ______________________________

Passive transport
40
(No Transcript)
41
Tonicity and osmosis
Passive transport

• ____________ low solute (high water) has LOW
  osmotic potential (LOW osmotic pressure). PURE
  WATER is the most hypotonic
• ____________ high solute (low water) has HIGH
  osmotic potential (pressure). Concentrated
  solutions (salt and sugar preservatives) are
  highly hypertonic.

42
(No Transcript)
43
Adaptations to osmotic effects
Passive transport

• In a hypotonic environment
• Bacteria, algae have cell walls so they wont
  burst they just become ____________.
• Amoebas, ciliates have contractile vacuoles
  constantly pumping water OUT
• In a hypertonic environment
• Halobacteria actually absorb salt to try and stay
  isotonic so they wont LOSE water (ex. Dead sea,
  Great Salt Lake)

44
Transport mechanisms

• ____________transport requires ____________ and
  carrier proteins, gradient ____________
• Examples against gradient, faster than
  diffusion, large, charged molecules that cant go
  through membrane all require energy
• Carrier-mediated active transport (permeases/
  pumps)
• Group translocation transported molecule
  chemically altered
• Bulk transport ______________________
  ______________________________________

45
Carrier mediated active transport
Group translocation
See Na/K pump movie
45
46
Bulk transport (________________) involves
vacuole/vessicle formation
Active transport
Liquids, solutions apicomplexans
Large particles, whole cells Amoeba
46
47
Active transport
48
48
49
MICROBIAL GROWTH
50
Microbial growth

1. Environmental influences on growth
2. Biology stages of growth

51
1. Environmental influences on microbial growth

• temperature
• oxygen requirements
• pH
• electromagnetic radiation
• barometric pressure

52
a. Temperature 3 cardinal temperatures
Environmental influences

• Minimum temperature lowest temperature that
  permits a microbes growth and metabolism
• Maximum temperature highest temperature that
  permits a microbes growth and metabolism
• ____________temperature promotes the fastest
  rate of growth and metabolism

53
3 temperature adaptation groups
Environmental influences

1. __________________ optimum temperature below
   15oC, capable of growth at 0oC
2. ________________ optimum temperature 20o-40oC,
   most human pathogens
3. ________________ optimum temperature greater
   than 45oC

54
3 temperature adaptation groups
Environmental influences
55
Thermus aquaticus

• DNA polymerase (known as Taq polymerase) used in
  PCR (polymerase chain reaction)
• ________________(1983) Nobel Prize in Chemistry
  - 1993
• Enzyme is HEAT STABLE so during cycling of the
  PCR machine (95-55-77C) it does not get
  destroyed
• Huge advance in biotechnology

56
b. Oxygen requirements
Environmental influences

• Depends on whether cell can handle toxic
  byproducts (superoxide, peroxide)
• ________________________________
• ________________________________

57
Aerobes vs. anaerobes
Environmental influences --Oxygen requirements

• ______________ grown in normal O2, can handle
  by-products. Some are facultative anaerobes.
  Microaerophile cannot grow under anaerobic
  conditions, but can handle some O2.
• ________________
• strict die in presence of O2.
• Aerotolerant cannot perform aerobic
  respiration, but are not killed by O2

58
Environmental influences
_____________________ broth absorbs O2
from air
59

• Aerobic (Pseudomonas)
• Facultative anaerobe (Staph aureus)
• Facultative anaerobe (E. coli)
• Obligate anaerobe (Clostridium)

60

• Anaerobic environmental chamber
• Anaerobic jar uses gas packs that provide a
  defined atmosphere
• O2 removed from atmosphere H2 ? water
• Also used for ________________

61
c. pH, pressure and EM radiation
Environmental influences

• pH majority grow between 6-8
• Acidophiles, Alkalinophiles
• Osmotic pressure most are in hypotonic or
  isotonic
• Osmophiles/halophiles grow in hypertonic (high
  osmotic pressure) can cause food spoilage
• Hydrostatic pressure barophiles (deep sea)
• EM radiation UV and ionizing rays are used in
  microbial control. Damage DNA.

62
2. Biology of microbial growth

• a. Cell division binary fission
• b. Population growth rate
• Generation/doubling time
• Growth curve stages
• c. Methods for analyzing growth

63
a. ______________________ dividing in two
Biology of microbial growth
64
b. Population growth rate Exponential growth
Biology of microbial growth

• Nf total number of cells at some point
• Ni starting number of cells
• n generation number
• elapsed time / generation time (t/gen)
• 2n number of cells in that generation

65
b. Population growth curve
Biology of microbial growth

• Shows growth progress over a time period ?
  cells/time
• Steps
• Inoculate culture and incubate
• Sample (volume) at time intervals
• Plate onto solid media
• Count number of cells (get cells/volume)

66
b. Stages of Growth curve
Biology of microbial growth
67
Growth curve
Biology of microbial growth

1. ________ phase flat period of adjustment,
   enlargement little growth
2. ____________ growth phase a period of maximum
   growth will continue as long as cells have
   adequate nutrients a favorable environment
3. ______________ phase rate of cell growth equals
   rate of cell death cause by depleted nutrients
   O2, excretion of organic acids pollutants
4. ___________ phase as limiting factors
   intensify, cells die exponentially in their own
   wastes

68
Importance of growth curve
Biology of microbial growth

• Antimicrobials more effective on exponential
  phase
• Infectivity early, middle stages more likely
  to pass microbe to others
• Course of infection fast growing microbes can
  overwhelm host defenses

69
c. Methods for analyzing growth

• Inoculate culture
• Count cells
• ________________ use spectrophotometer
• ________________
• Direct, total cell count (hemocytometer)
• Viable plate count (look at CFUs)
• Coulter counter/Flow cytometer

70
Turbidity
Biology of microbial growth
71
Enumeration - Direct microscopic count
Biology of microbial growth
72
(No Transcript)
73
Enumeration - Electronic counting
Biology of microbial growth