chapter 7 power point le

8/9/2019 Chapter 7 Power Point Le

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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

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