elements of microbial nutrition, ecology and growth chapter 7
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Elements of Microbial Nutrition, Ecology and Growth Chapter 7. 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 - PowerPoint PPT PresentationTRANSCRIPT
Elements of Microbial Nutrition, Ecology and
Growth
Chapter 7
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
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
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
Microbial nutrition
Chemical composition of cytoplasm
70% water proteins 96% of cell is composed of 6 elements
• ____________
• ____________
• ____________
• ____________
• ____________ See Table 7.2 for E. coli
Microbial nutrition
8
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
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
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
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
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
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
Important mineral ions
Potassium Sodium Calcium Magnesium Iron
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
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
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
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
Carbon source
Energy source
photoautotrophs CO2 ____________
chemoautotrophs CO2 Simple inorganic ____________
photoheterotrophs organic ____________
chemoheterotrophs organic Metabolizing organic ____________
How microbes feed PRINT FULL SIZE
examples
____________– • Photoautotrophs – photosynthesis6CO2 + 12H2O + light energy C6H12O6 + 6O2 + 6H2O
• Chemoautotrophs – methanogens
4H2 + CO2 CH4 + 2H2O
____________
• ChemoheterotrophsC6H12O6 + 6O2 6CO2 + 6H2O + energy
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
How microbes feed
saprobes
• Cannot engulf large particles of food
• Substrate is digested _________ by secreted enzymes
• Small molecules are transported into cell
How microbes feed
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How microbes feed
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
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
27
Ecological Associations Among Microorganisms
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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
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
30
Figure 7.13
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
transport mechanisms
1. ____________– require no energy input from cell (uses laws of physics, like entropy)
2. ____________– require energy input from cell
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
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
diffusion
• Molecules move along gradient:
• High low concentration
• Due to RANDOM motion – increased by heat (entropy)
• Evidence: Brownian movement
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
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
Facilitated diffusion
38
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
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
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
____________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
45
Carrier mediated active transport
Group translocation
See Na/K pump movie
46
Bulk transport (________________) – involves vacuole/vessicle formation
Active transport
Large particles, whole cellsAmoeba
Liquids, solutionsapicomplexans
Active transport
48
MICROBIAL GROWTH
Microbial growth
1. Environmental influences on growth
2. Biology – stages of growth
1. Environmental influences on microbial growth
temperature oxygen requirements pH electromagnetic radiation barometric pressure
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
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
3 temperature adaptation groupsEnvironmental influences
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
b. Oxygen requirements
Depends on whether cell can handle toxic byproducts (superoxide, peroxide)
________________________________ ________________________________
Environmental influences
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
_____________________ broth – absorbs O2 from airEnvironmental influences
Aerobic (Pseudomonas)
Facultative anaerobe (Staph aureus)
Facultative anaerobe (E. coli)
Obligate anaerobe (Clostridium)
Anaerobic environmental chamber
Anaerobic jar – uses gas packs that provide a defined atmosphere
O2 removed from atmosphere + H2 water
Also used for ________________
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
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
a. ______________________– dividing in twoBiology of microbial growth
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
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
b. Stages of Growth curve
Biology of microbial growth
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
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
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
Turbidity
Biology of microbial growth
Enumeration - Direct microscopic count
Biology of microbial growth
Enumeration - Electronic countingBiology of microbial growth