Elements of Microbial Nutrition, Ecology and Growth Chapter 7
description
Transcript of Elements of Microbial Nutrition, Ecology and Growth Chapter 7
![Page 1: Elements of Microbial Nutrition, Ecology and Growth Chapter 7](https://reader035.fdocuments.net/reader035/viewer/2022081421/568146ff550346895db43b72/html5/thumbnails/1.jpg)
Elements of Microbial Nutrition, Ecology and
Growth
Chapter 7
![Page 2: Elements of Microbial Nutrition, Ecology and Growth Chapter 7](https://reader035.fdocuments.net/reader035/viewer/2022081421/568146ff550346895db43b72/html5/thumbnails/2.jpg)
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
![Page 3: Elements of Microbial Nutrition, Ecology and Growth Chapter 7](https://reader035.fdocuments.net/reader035/viewer/2022081421/568146ff550346895db43b72/html5/thumbnails/3.jpg)
Nutrients ____________– 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
Microbial nutrition
![Page 4: Elements of Microbial Nutrition, Ecology and Growth Chapter 7](https://reader035.fdocuments.net/reader035/viewer/2022081421/568146ff550346895db43b72/html5/thumbnails/4.jpg)
Nutrients ____________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
Microbial nutrition
![Page 5: Elements of Microbial Nutrition, Ecology and Growth Chapter 7](https://reader035.fdocuments.net/reader035/viewer/2022081421/568146ff550346895db43b72/html5/thumbnails/5.jpg)
![Page 6: Elements of Microbial Nutrition, Ecology and Growth Chapter 7](https://reader035.fdocuments.net/reader035/viewer/2022081421/568146ff550346895db43b72/html5/thumbnails/6.jpg)
Microbial nutrition
![Page 7: Elements of Microbial Nutrition, Ecology and Growth Chapter 7](https://reader035.fdocuments.net/reader035/viewer/2022081421/568146ff550346895db43b72/html5/thumbnails/7.jpg)
Chemical composition of cytoplasm
70% water proteins 96% of cell is composed of 6 elements
• ____________
• ____________
• ____________
• ____________
• ____________ See Table 7.2 for E. coli
Microbial nutrition
![Page 8: Elements of Microbial Nutrition, Ecology and Growth Chapter 7](https://reader035.fdocuments.net/reader035/viewer/2022081421/568146ff550346895db43b72/html5/thumbnails/8.jpg)
8
![Page 9: Elements of Microbial Nutrition, Ecology and Growth Chapter 7](https://reader035.fdocuments.net/reader035/viewer/2022081421/568146ff550346895db43b72/html5/thumbnails/9.jpg)
How do organisms obtain carbon? ____________– 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
- 6 major elementsMicrobial nutrition
![Page 10: Elements of Microbial Nutrition, Ecology and Growth Chapter 7](https://reader035.fdocuments.net/reader035/viewer/2022081421/568146ff550346895db43b72/html5/thumbnails/10.jpg)
Nitrogen Main reservoir is nitrogen gas (N2) 79% of earth’s 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.
6 major elements
![Page 11: Elements of Microbial Nutrition, Ecology and Growth Chapter 7](https://reader035.fdocuments.net/reader035/viewer/2022081421/568146ff550346895db43b72/html5/thumbnails/11.jpg)
Oxygen
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
6 major elements
![Page 12: Elements of Microbial Nutrition, Ecology and Growth Chapter 7](https://reader035.fdocuments.net/reader035/viewer/2022081421/568146ff550346895db43b72/html5/thumbnails/12.jpg)
Hydrogen
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
6 major elements
![Page 13: Elements of Microbial Nutrition, Ecology and Growth Chapter 7](https://reader035.fdocuments.net/reader035/viewer/2022081421/568146ff550346895db43b72/html5/thumbnails/13.jpg)
Phosphorous
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)
6 major elements
![Page 14: Elements of Microbial Nutrition, Ecology and Growth Chapter 7](https://reader035.fdocuments.net/reader035/viewer/2022081421/568146ff550346895db43b72/html5/thumbnails/14.jpg)
Sulfur
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
6 major elements
![Page 15: Elements of Microbial Nutrition, Ecology and Growth Chapter 7](https://reader035.fdocuments.net/reader035/viewer/2022081421/568146ff550346895db43b72/html5/thumbnails/15.jpg)
Important mineral ions
Potassium Sodium Calcium Magnesium Iron
![Page 16: Elements of Microbial Nutrition, Ecology and Growth Chapter 7](https://reader035.fdocuments.net/reader035/viewer/2022081421/568146ff550346895db43b72/html5/thumbnails/16.jpg)
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
![Page 17: Elements of Microbial Nutrition, Ecology and Growth Chapter 7](https://reader035.fdocuments.net/reader035/viewer/2022081421/568146ff550346895db43b72/html5/thumbnails/17.jpg)
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
![Page 18: Elements of Microbial Nutrition, Ecology and Growth Chapter 7](https://reader035.fdocuments.net/reader035/viewer/2022081421/568146ff550346895db43b72/html5/thumbnails/18.jpg)
terminology
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)
How microbes feed
![Page 19: Elements of Microbial Nutrition, Ecology and Growth Chapter 7](https://reader035.fdocuments.net/reader035/viewer/2022081421/568146ff550346895db43b72/html5/thumbnails/19.jpg)
Facultative vs. obligate
____________– 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.
How microbes feed
![Page 20: Elements of Microbial Nutrition, Ecology and Growth Chapter 7](https://reader035.fdocuments.net/reader035/viewer/2022081421/568146ff550346895db43b72/html5/thumbnails/20.jpg)
Carbon source
Energy source
photoautotrophs CO2 ____________
chemoautotrophs CO2 Simple inorganic ____________
photoheterotrophs organic ____________
chemoheterotrophs organic Metabolizing organic ____________
How microbes feed PRINT FULL SIZE
![Page 21: Elements of Microbial Nutrition, Ecology and Growth Chapter 7](https://reader035.fdocuments.net/reader035/viewer/2022081421/568146ff550346895db43b72/html5/thumbnails/21.jpg)
examples
____________– • Photoautotrophs – photosynthesis6CO2 + 12H2O + light energy C6H12O6 + 6O2 + 6H2O
• Chemoautotrophs – methanogens
4H2 + CO2 CH4 + 2H2O
____________
• ChemoheterotrophsC6H12O6 + 6O2 6CO2 + 6H2O + energy
How microbes feed
![Page 22: Elements of Microbial Nutrition, Ecology and Growth Chapter 7](https://reader035.fdocuments.net/reader035/viewer/2022081421/568146ff550346895db43b72/html5/thumbnails/22.jpg)
____________– 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
How microbes feed
![Page 23: Elements of Microbial Nutrition, Ecology and Growth Chapter 7](https://reader035.fdocuments.net/reader035/viewer/2022081421/568146ff550346895db43b72/html5/thumbnails/23.jpg)
saprobes
• Cannot engulf large particles of food
• Substrate is digested _________ by secreted enzymes
• Small molecules are transported into cell
How microbes feed
![Page 24: Elements of Microbial Nutrition, Ecology and Growth Chapter 7](https://reader035.fdocuments.net/reader035/viewer/2022081421/568146ff550346895db43b72/html5/thumbnails/24.jpg)
24
How microbes feed
![Page 25: Elements of Microbial Nutrition, Ecology and Growth Chapter 7](https://reader035.fdocuments.net/reader035/viewer/2022081421/568146ff550346895db43b72/html5/thumbnails/25.jpg)
Symbiosis Means “________________________” Organisms (____________) have close association
1. ____________=obligatory, both symbionts benefit• Termite gut flagellates
2. ____________=commensal receives benefit, symbiont (host) is neither harmed nor benefited• satellitism, commensal intestinal bacteria (normal microbial
flora)
3. ____________= parasite benefits, host is harmed• Intestinal helminths, Rickettsia, all viruses
How microbes live
![Page 26: Elements of Microbial Nutrition, Ecology and Growth Chapter 7](https://reader035.fdocuments.net/reader035/viewer/2022081421/568146ff550346895db43b72/html5/thumbnails/26.jpg)
Non-symbiotic microbial associations
organisms are free-living; relationships not required for survival• ____________– members cooperate and
share nutrients
• ____________– some members are inhibited or destroyed by others
How microbes live
![Page 27: Elements of Microbial Nutrition, Ecology and Growth Chapter 7](https://reader035.fdocuments.net/reader035/viewer/2022081421/568146ff550346895db43b72/html5/thumbnails/27.jpg)
27
Ecological Associations Among Microorganisms
![Page 28: Elements of Microbial Nutrition, Ecology and Growth Chapter 7](https://reader035.fdocuments.net/reader035/viewer/2022081421/568146ff550346895db43b72/html5/thumbnails/28.jpg)
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
![Page 29: Elements of Microbial Nutrition, Ecology and Growth Chapter 7](https://reader035.fdocuments.net/reader035/viewer/2022081421/568146ff550346895db43b72/html5/thumbnails/29.jpg)
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
![Page 30: Elements of Microbial Nutrition, Ecology and Growth Chapter 7](https://reader035.fdocuments.net/reader035/viewer/2022081421/568146ff550346895db43b72/html5/thumbnails/30.jpg)
30
Figure 7.13
![Page 31: Elements of Microbial Nutrition, Ecology and Growth Chapter 7](https://reader035.fdocuments.net/reader035/viewer/2022081421/568146ff550346895db43b72/html5/thumbnails/31.jpg)
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
![Page 32: Elements of Microbial Nutrition, Ecology and Growth Chapter 7](https://reader035.fdocuments.net/reader035/viewer/2022081421/568146ff550346895db43b72/html5/thumbnails/32.jpg)
transport mechanisms
1. ____________– require no energy input from cell (uses laws of physics, like entropy)
2. ____________– require energy input from cell
![Page 33: Elements of Microbial Nutrition, Ecology and Growth Chapter 7](https://reader035.fdocuments.net/reader035/viewer/2022081421/568146ff550346895db43b72/html5/thumbnails/33.jpg)
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
![Page 34: Elements of Microbial Nutrition, Ecology and Growth Chapter 7](https://reader035.fdocuments.net/reader035/viewer/2022081421/568146ff550346895db43b72/html5/thumbnails/34.jpg)
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: ____________> ____________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
![Page 35: Elements of Microbial Nutrition, Ecology and Growth Chapter 7](https://reader035.fdocuments.net/reader035/viewer/2022081421/568146ff550346895db43b72/html5/thumbnails/35.jpg)
diffusion
• Molecules move along gradient:
• High low concentration
• Due to RANDOM motion – increased by heat (entropy)
• Evidence: Brownian movement
![Page 36: Elements of Microbial Nutrition, Ecology and Growth Chapter 7](https://reader035.fdocuments.net/reader035/viewer/2022081421/568146ff550346895db43b72/html5/thumbnails/36.jpg)
Diffusion in cells
Small, nonpolar molecules can diffuse across cell membrane (oxygen, small lipids)
Polar molecules – ____________ ________________________ (facilitated diffusion – still PASSIVE transport – using energy of gradient)
Passive transport
![Page 37: Elements of Microbial Nutrition, Ecology and Growth Chapter 7](https://reader035.fdocuments.net/reader035/viewer/2022081421/568146ff550346895db43b72/html5/thumbnails/37.jpg)
Facilitated diffusion 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
Passive transport
![Page 38: Elements of Microbial Nutrition, Ecology and Growth Chapter 7](https://reader035.fdocuments.net/reader035/viewer/2022081421/568146ff550346895db43b72/html5/thumbnails/38.jpg)
Facilitated diffusion
38
![Page 39: Elements of Microbial Nutrition, Ecology and Growth Chapter 7](https://reader035.fdocuments.net/reader035/viewer/2022081421/568146ff550346895db43b72/html5/thumbnails/39.jpg)
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 ______________________________
______________________________
Pa
ssive tra
nsp
ort
![Page 40: Elements of Microbial Nutrition, Ecology and Growth Chapter 7](https://reader035.fdocuments.net/reader035/viewer/2022081421/568146ff550346895db43b72/html5/thumbnails/40.jpg)
![Page 41: Elements of Microbial Nutrition, Ecology and Growth Chapter 7](https://reader035.fdocuments.net/reader035/viewer/2022081421/568146ff550346895db43b72/html5/thumbnails/41.jpg)
Tonicity and osmosis
____________– 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.
Passive transport
![Page 42: Elements of Microbial Nutrition, Ecology and Growth Chapter 7](https://reader035.fdocuments.net/reader035/viewer/2022081421/568146ff550346895db43b72/html5/thumbnails/42.jpg)
![Page 43: Elements of Microbial Nutrition, Ecology and Growth Chapter 7](https://reader035.fdocuments.net/reader035/viewer/2022081421/568146ff550346895db43b72/html5/thumbnails/43.jpg)
Adaptations to osmotic effects
In a hypotonic environment: Bacteria, algae have cell walls so they won’t
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 won’t LOSE water (ex. Dead sea, Great Salt Lake)
Passive transport
![Page 44: Elements of Microbial Nutrition, Ecology and Growth Chapter 7](https://reader035.fdocuments.net/reader035/viewer/2022081421/568146ff550346895db43b72/html5/thumbnails/44.jpg)
____________transport – requires ____________ and carrier proteins, gradient ____________• Examples: against gradient, faster than diffusion, large,
charged molecules that can’t go through membrane – all require energy
• Carrier-mediated active transport (permeases/ pumps)
• Group translocation – transported molecule chemically altered
• Bulk transport – ______________________
______________________________________
Transport mechanisms
![Page 45: Elements of Microbial Nutrition, Ecology and Growth Chapter 7](https://reader035.fdocuments.net/reader035/viewer/2022081421/568146ff550346895db43b72/html5/thumbnails/45.jpg)
45
Carrier mediated active transport
Group translocation
See Na/K pump movie
![Page 46: Elements of Microbial Nutrition, Ecology and Growth Chapter 7](https://reader035.fdocuments.net/reader035/viewer/2022081421/568146ff550346895db43b72/html5/thumbnails/46.jpg)
46
Bulk transport (________________) – involves vacuole/vessicle formation
Active transport
Large particles, whole cellsAmoeba
Liquids, solutionsapicomplexans
![Page 47: Elements of Microbial Nutrition, Ecology and Growth Chapter 7](https://reader035.fdocuments.net/reader035/viewer/2022081421/568146ff550346895db43b72/html5/thumbnails/47.jpg)
Active transport
![Page 48: Elements of Microbial Nutrition, Ecology and Growth Chapter 7](https://reader035.fdocuments.net/reader035/viewer/2022081421/568146ff550346895db43b72/html5/thumbnails/48.jpg)
48
![Page 49: Elements of Microbial Nutrition, Ecology and Growth Chapter 7](https://reader035.fdocuments.net/reader035/viewer/2022081421/568146ff550346895db43b72/html5/thumbnails/49.jpg)
MICROBIAL GROWTH
![Page 50: Elements of Microbial Nutrition, Ecology and Growth Chapter 7](https://reader035.fdocuments.net/reader035/viewer/2022081421/568146ff550346895db43b72/html5/thumbnails/50.jpg)
Microbial growth
1. Environmental influences on growth
2. Biology – stages of growth
![Page 51: Elements of Microbial Nutrition, Ecology and Growth Chapter 7](https://reader035.fdocuments.net/reader035/viewer/2022081421/568146ff550346895db43b72/html5/thumbnails/51.jpg)
1. Environmental influences on microbial growth
temperature oxygen requirements pH electromagnetic radiation barometric pressure
![Page 52: Elements of Microbial Nutrition, Ecology and Growth Chapter 7](https://reader035.fdocuments.net/reader035/viewer/2022081421/568146ff550346895db43b72/html5/thumbnails/52.jpg)
a. Temperature:3 cardinal temperatures
Minimum temperature – lowest temperature that permits a microbe’s growth and metabolism
Maximum temperature – highest temperature that permits a microbe’s growth and metabolism
____________temperature – promotes the fastest rate of growth and metabolism
Environmental influences
![Page 53: Elements of Microbial Nutrition, Ecology and Growth Chapter 7](https://reader035.fdocuments.net/reader035/viewer/2022081421/568146ff550346895db43b72/html5/thumbnails/53.jpg)
3 temperature adaptation groups
1. __________________– optimum temperature below 15oC, capable of growth at 0oC
2. ________________– optimum temperature 20o-40oC, most human pathogens
3. ________________– optimum temperature greater than 45oC
Environmental influences
![Page 54: Elements of Microbial Nutrition, Ecology and Growth Chapter 7](https://reader035.fdocuments.net/reader035/viewer/2022081421/568146ff550346895db43b72/html5/thumbnails/54.jpg)
3 temperature adaptation groupsEnvironmental influences
![Page 55: Elements of Microbial Nutrition, Ecology and Growth Chapter 7](https://reader035.fdocuments.net/reader035/viewer/2022081421/568146ff550346895db43b72/html5/thumbnails/55.jpg)
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 (95-55-77°C) it does not get destroyed
Huge advance in biotechnology
![Page 56: Elements of Microbial Nutrition, Ecology and Growth Chapter 7](https://reader035.fdocuments.net/reader035/viewer/2022081421/568146ff550346895db43b72/html5/thumbnails/56.jpg)
b. Oxygen requirements
Depends on whether cell can handle toxic byproducts (superoxide, peroxide)
________________________________ ________________________________
Environmental influences
![Page 57: Elements of Microbial Nutrition, Ecology and Growth Chapter 7](https://reader035.fdocuments.net/reader035/viewer/2022081421/568146ff550346895db43b72/html5/thumbnails/57.jpg)
Aerobes vs. anaerobes ______________– 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
Environmental influences--Oxygen requirements
![Page 58: Elements of Microbial Nutrition, Ecology and Growth Chapter 7](https://reader035.fdocuments.net/reader035/viewer/2022081421/568146ff550346895db43b72/html5/thumbnails/58.jpg)
_____________________ broth – absorbs O2 from airEnvironmental influences
![Page 59: Elements of Microbial Nutrition, Ecology and Growth Chapter 7](https://reader035.fdocuments.net/reader035/viewer/2022081421/568146ff550346895db43b72/html5/thumbnails/59.jpg)
Aerobic (Pseudomonas)
Facultative anaerobe (Staph aureus)
Facultative anaerobe (E. coli)
Obligate anaerobe (Clostridium)
![Page 60: Elements of Microbial Nutrition, Ecology and Growth Chapter 7](https://reader035.fdocuments.net/reader035/viewer/2022081421/568146ff550346895db43b72/html5/thumbnails/60.jpg)
Anaerobic environmental chamber
Anaerobic jar – uses gas packs that provide a defined atmosphere
O2 removed from atmosphere + H2 water
Also used for ________________
![Page 61: Elements of Microbial Nutrition, Ecology and Growth Chapter 7](https://reader035.fdocuments.net/reader035/viewer/2022081421/568146ff550346895db43b72/html5/thumbnails/61.jpg)
c. pH, pressure and EM radiation 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.
Environmental influences
![Page 62: Elements of Microbial Nutrition, Ecology and Growth Chapter 7](https://reader035.fdocuments.net/reader035/viewer/2022081421/568146ff550346895db43b72/html5/thumbnails/62.jpg)
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
![Page 63: Elements of Microbial Nutrition, Ecology and Growth Chapter 7](https://reader035.fdocuments.net/reader035/viewer/2022081421/568146ff550346895db43b72/html5/thumbnails/63.jpg)
a. ______________________– dividing in twoBiology of microbial growth
![Page 64: Elements of Microbial Nutrition, Ecology and Growth Chapter 7](https://reader035.fdocuments.net/reader035/viewer/2022081421/568146ff550346895db43b72/html5/thumbnails/64.jpg)
b. Population growth rate: Exponential 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
Biology of microbial growth
![Page 65: Elements of Microbial Nutrition, Ecology and Growth Chapter 7](https://reader035.fdocuments.net/reader035/viewer/2022081421/568146ff550346895db43b72/html5/thumbnails/65.jpg)
b. Population growth curve
Shows growth progress over a time period #cells/time
Steps:1.Inoculate culture and incubate
2.Sample (volume) at time intervals
3.Plate onto solid media4.Count number of cells (get #cells/volume)
Biology of microbial growth
![Page 66: Elements of Microbial Nutrition, Ecology and Growth Chapter 7](https://reader035.fdocuments.net/reader035/viewer/2022081421/568146ff550346895db43b72/html5/thumbnails/66.jpg)
b. Stages of Growth curve
Biology of microbial growth
![Page 67: Elements of Microbial Nutrition, Ecology and Growth Chapter 7](https://reader035.fdocuments.net/reader035/viewer/2022081421/568146ff550346895db43b72/html5/thumbnails/67.jpg)
Growth curve1. ________ 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
Biology of microbial growth
![Page 68: Elements of Microbial Nutrition, Ecology and Growth Chapter 7](https://reader035.fdocuments.net/reader035/viewer/2022081421/568146ff550346895db43b72/html5/thumbnails/68.jpg)
Importance of growth curve
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
Biology of microbial growth
![Page 69: Elements of Microbial Nutrition, Ecology and Growth Chapter 7](https://reader035.fdocuments.net/reader035/viewer/2022081421/568146ff550346895db43b72/html5/thumbnails/69.jpg)
c. Methods for analyzing growth
1. Inoculate culture
2. Count cells• ________________– use spectrophotometer• ________________
• Direct, total cell count (hemocytometer)
• Viable plate count (look at CFUs)
• Coulter counter/Flow cytometer
![Page 70: Elements of Microbial Nutrition, Ecology and Growth Chapter 7](https://reader035.fdocuments.net/reader035/viewer/2022081421/568146ff550346895db43b72/html5/thumbnails/70.jpg)
Turbidity
Biology of microbial growth
![Page 71: Elements of Microbial Nutrition, Ecology and Growth Chapter 7](https://reader035.fdocuments.net/reader035/viewer/2022081421/568146ff550346895db43b72/html5/thumbnails/71.jpg)
Enumeration - Direct microscopic count
Biology of microbial growth
![Page 72: Elements of Microbial Nutrition, Ecology and Growth Chapter 7](https://reader035.fdocuments.net/reader035/viewer/2022081421/568146ff550346895db43b72/html5/thumbnails/72.jpg)
![Page 73: Elements of Microbial Nutrition, Ecology and Growth Chapter 7](https://reader035.fdocuments.net/reader035/viewer/2022081421/568146ff550346895db43b72/html5/thumbnails/73.jpg)
Enumeration - Electronic countingBiology of microbial growth