chapter 7 power point le
TRANSCRIPT
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Foundations in Microbiology
Chapter
7
PowerPoint to accompany
Fifth Edition
Talaro
Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
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Elements of Microbial Nutrition,
Ecology and Growth
Chapter 7
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Microbial nutrition
Macronutrients required in large quantities;
play principal roles in cell structure &
metabolism
proteins, carbohydrates
Micronutrientsor trace elements required
in small amounts; involved in enzyme function
& maintenance of protein structure
manganese, zinc, nickel
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Nutrients
Inorganic 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
Organic nutrients- contain carbon and hydrogen
atoms and are usually the products of living things methane (CH
4), carbohydrates, lipids, proteins, and nucleic
acids
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Chemical composition of cytoplasm
70% water
proteins
96% of cell is composed of 6 elements
Carbon
Hydrogen
Oxygen
Phosphorous
Sulfur
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Obtaining Carbon
Heterotroph an organism that must obtain
carbon in an organic form made by other
living organisms such as proteins,
carbohydrates, lipids and nucleic acids
Autotroph - an organism that uses CO2, an
inorganic gas as its carbon source
not dependent on other living things
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Nitrogen
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 forheterotrophs
Some bacteria & algae use inorganic N nutrients(NO
3
-, NO2
-, or NH3)
Some bacteria can fix N2
Regardless of how N enters the cell, it must beconverted to NH
3, the only form that can be combined
with carbon to synthesis amino acids, etc.
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Oxygen
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
O2makes up 20% of atmosphere
essential to metabolism of many organisms
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Hydrogen
major element in all organic compounds &
several inorganic ones (water, salts & gases)
gases are produced & used by microbes
roles of hydrogen
maintaining pH
forming H bonds between molecules
serving as the source of free energy in oxidation-
reduction reactions of respiration
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Phosphorous
main inorganic source is phosphate (PO4-3)
derived from phosphoric acid (H3PO4) found in
rocks & oceanic mineral deposits key component of nucleic acids, essential to
genetics
serves in energy transfers (ATP)
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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
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Important mineral ions
Potassium
Sodium
Calcium Magnesium
Iron
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Growth factors
organic compounds that cannot be synthesized
by an organism & must be provided as a
nutrient
essential amino acids, vitamins
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Carbonsource
Energy source
photoautotrophs CO2 sunlight
chemoautotrophs CO2 Simple inorganic
chemicals
photoheterotrophs organic sunlight
chemoheterotrophs organic Metabolizingorganic cpds
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Saprobes decompose dead organisms,
recycle elements, release enzymes to digest
materials
Parasites utilize tissues and fluids of a living
host and cause harm
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saprobes
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Transport mechanisms Passive transport do not require energy, substances exist in
a gradient and move from areas of higher concentrationtowards areas of lower concentration
Diffusion
Osmosis - water
Facilitated diffusion requires a carrier
Active transport require energy and carrier proteins,gradient independent
Carrier-mediated active transport
Group translocation transported molecule chemicallyaltered
Bulk transport endocytosis, exocytosis, pinocytosis
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diffusion
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osmosis
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passive transport
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Active transport
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Bulk transport
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Environmental influences on
microbial growth temperature
oxygen requirements pH
electromagnetic radiation
barometric pressure
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3 cardinal temperatures
Minimum temperature lowest temperature
that permits a microbes growth and
metabolism
Maximum temperature highest
temperature that permits a microbes growth
and metabolism
Optimum temperature promotes the fastest
rate of growth and metabolism
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3 temperature adaptation groups
1. Psychrophiles optimum temperature
below 15oC, capable of growth at 0oC
2. Mesophiles optimum temperature 20o-
40oC, most human pathogens
3. Thermophiles optimum temperature
greater than 45oC
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3 temperature adaptation groups
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Oxygen requirements
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Microbial associations
Symbiotic organisms live in close nutritional
relationships; required by one or both
members
Mutualism obligatory, dependent; both
members benefit
Commensalism commensal member benefits,
other member not harmedParasitism parasite is dependent and benefits;
host is harmed
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Microbial associations
Non-symbiotic organisms are free-living;
relationships not required for survival
Synergism members cooperate and share
nutrients
Antagonism some member are inhibited or
destroyed by others
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Binary Fission
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Population growth
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Growth curve
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Growth curve1. Lag phase flat period of adjustment, enlargement;
little growth
2. Exponential growth phase a period of maximumgrowth will continue as long as cells have adequatenutrients & a favorable environment
3. Stationary phase rate of cell growth equals rate of celldeath cause by depleted nutrients & O
2, excretion of
organic acids & pollutants
4. Death phase as limiting factors intensify, cells dieexponentially in their own wastes
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Turbidity
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Direct microscopic count
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Electronic counting