Mcb2010 Exam 2D - Ch. 7 Microbial Nutrition

Front 1

Nutrition

Back 1

Process by which chemical substances (nutrients) are acquired by the environment and used in cellular activities like metabolism and growth.

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Essential nutrient

Back 2

Any substance that must be provided to an organism

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Two categories of essential nutrients are?

Back 3

Macro
Micro nutrients

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Macronutrient

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- Required in large qts
- Principal roles in cell structure and metabolism
- Carbon, hydrogen, oxygen,

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Micronutrient

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Trace elements
- Manganeses, zinc, nickel
- smaller amts.
- varies

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Heterotroph

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- Obtains carbon in an organic form made by OTHER LIVING ORGANISMS
e.g. proteins, carbs, lipids, nucleic acids

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Autotroph

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An organism using CO2, an inorganic gas, as its carbon source
- not nutritionally dependent on other living things

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Requirements for Growth:

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1. Physical (temp, pH, osmotic pressure)
2. Chemical (water, carbon, nitrogen, minerals, oxygen, organic growth factors)
3. Temperature

Front 9

Why are organisms particular to a pH?

Back 9

Enzymes denature at certain pHs. (It affects metabolism).

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3 primary groups of Temperature

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1. Psychrophiles
2. Mesophiles
3. Thermophiles

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Most bacteria favor which temperature?

Back 11

- Human body temp
- Mesophile (2nd temp group)

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Nutritional Types: Main determinants of nutritional type are?

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1. Carbon source
2. Energy source

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2 Types of energy sources

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Chemotroph - from chemical compounds
Phototroph - through photosynthesis

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Why is oxygen impt as a factor affecting microbes?

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Amt of oxygen determines how much ATP produced.

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Environmental factors affecting the function of metabolic enzymes.

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Temperature, Oxygen requirements, pH, Osmotic pressure, Barometric pressure

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Table 7.4
Photoautroph examples include

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Algae, plants, cyanobacteria

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Table 7.4
Chemoautotroph examples include

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Only certain bacteria, such as methanogens, deep-sea vent bacteria

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Table 7.4
Chemoheterotroph

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Protozoa, fungi, many bacteria, animals

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Table 7.4
Saprobe

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Fungi, bacteria (decomposers)

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Table 7.4
Parasite

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Various parasites and pathogens; can be bacteria, fungi, protozoa, animals

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Table 7.4
Photoheterotroph examples....

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Purple and green photosynthesis bacteria

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Regarding temperature,
Describe Psychrophiles.

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Max temperature below 15 C
Min temp less than -15 C

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Regarding temperature,
describe Mesophiles.

Back 23

Optimun temp 37 C; most human pathogens

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Regarding temperature,
describe Thermophiles.

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Optimum temp 70 C

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Gas Requirements (Oxygen) 3 points

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1. As oxygen is used it is transformed into several toxic products. [peroxide, hydroxyl radicals]
2. Most cells have developed enzymes that neutralize these chemicals: [superoxide dismutase, catalase]
3. If a microbe is not capable of dealing with toxic oxygen, it is forced to live in oxygen free habitats.

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Categories of Oxygen Requirement (3 main groups)

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1. Aerobe
2. Facultative anaerobe
3. Anaerobe

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Aerobe (category of oxygen requirement)

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- Uses oxygen and can detoxify it
a. Obligate aerobe - cannot grow without oxygen
b. Microaerophilic - requires only a small amt of oxygen.

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Facultative anaerobe

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Uses oxygen but can also grow in its absence

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Anaerobe (2 subgroups)

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- Does not use oxygen
a. Obligate = lacks enzymes to detoxify oxygen so cannot survive in an oxygen environment
b. Aerotolerant = does not utilize oxygen but can survive and grow in its presence

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Why doesn't hydrogen peroxide work effectively on scrapes?

Back 30

Because the bacteria neutralizes the chemicals with catalase. (see bubbles)

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2 Major Transport processes in cells

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Passive
Active

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Passive transport

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No energy expenditure required.
Concentration gradient.

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2 forms of passive transport

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Diffusion - random motion
Facilitated diffusion - binds to a carrier protein in membrane and is carried across

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Active transport

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Energy expended. No need for gradient. Transport rate increased. May occur against a concentration gradient.

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Active transport (1 Type)

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Carrier-mediated active transport - atoms/molecules are pumped into or out of the cell by specialized receptors. Driven by ATP or the proton motive force.

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Temperature adaptive groups (3)

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Psychrophiles
Mesophiles
Thermophiles

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Temp adaptive group: Psychrophiles

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- Can grow at or near 0 C.
- Have an optimum below 15 C

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Temp adaptive group: Mesophile

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- Can grow between 10 C and 50 C
- Optima btwn 20-40 C

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Temp adaptive group: Thermophile

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- Require temp above 45 C - 80 C

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Figure 7.11 - Demonstration of oxygen requirements.
Describe what was shown.
(Recall Tube 1, 2, 3, 4)

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- Oxygen concentration is highest at the top of the tube.
- When a series of tubes is inoculated with bacteria that differ in O2 requirements, the relative position of growth provides some indication of their adaptations to oxygen use.

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Fig. 7. 11
Tube 1 - White layer at top. Clear throughout.
Describe it.

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Aerobic.

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Fig. 7.11
Tube 2 - White layer with upper half mixed white and lower cloudy.

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Facultative anaerobes

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Fig. 7.11
Tube 3 - Top white layer with cloudiness throughout.

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Facultative anaerobe.

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Fig. 7.11
Tube 4 - No top white layer. Cloudy in middle to bottom.

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Obligate anaerobe.

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Effects of pH (3 points)

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- Majority of microorgas grow btwn pH 6-8
- Obligate acidophiles - grow at extreme acid pH
- Obligate Alkalinophiles - grow at extreme alkaline pH

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Osmotic Pressure (3 points)

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- Most microbes exist under hypotonic or isotonic conditions
- Halophiles - require a high concentration of salt
- Osmotolerant - do not require high concentration of solute but can tolerate it when it occurs

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Capnophiles

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Microbes that grow best at higher CO2 tensions than are normally present in the atmosphere

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Ecological Associations:
2 Major Classes

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Symbiotic
Nonsymbiotic

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Symbiotic relationship

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aka symbiosis
Organism living in close nutritional relationsihps; required by one or both members

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Nonsymbiotic relaitonship

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Organisms are free-living relationships
not required for survival.

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3 subgroups of Symbiosis

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Mutualism
Commensalism
Parasitism

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Mutualism

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Obligatory, dependent. Both members benefit.

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Commensalism

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Commensal benefits
Other member not harmed.

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Parasitism

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Parasite is dependent and benefits; host harmed.

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Nonsymbiotic subgroups (2).

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Synergism
Antagonism

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An example of Mutualism.

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Intestinal flora.

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An example of commensalism

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Vectors

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An example of Parasitism.

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Hookworm

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Several examples of Aerobes.

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Staphylococcus growing on skin.
Mold growing on orange.
Bathroom mold.
Epidermophyte microsporum.

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Examples of Anaerobes.

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Staph growing inside bone tissue.
Clostridium tetanii in the soil.

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Everything that an organism does is dependent on ......?

Back 61

Enzymes (and pH)

Front 62

Regarding osmotic pressure, fungi tend to have higher osmotic pressure resistance than ?

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Bacteria.
Ex: They can grow in high fructose corn syrups but not bacteria.
Just like adding salt to canned goods.

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Interrelationships Btwn Microbes and Humans

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Human body is a rich habitat for symbiotic bacteria, fungi, and a few protozoa = normal microbial flora

Front 64

Describe the relationship between bacteria and yeast in the vagina.

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They BALANCE each other!
If one overgrows > infection

Front 65

How do microbes control their different populations in the body?

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Producing fungicins and bacteriocins preventing overgrowth of their surroundings.

Front 66

The division of a bacterial cell occurs mainly through what?

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Binary fission

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Microbial Growth

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# of cells, NOT the cells' size
Hundreds of thousands increase

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The Study of Microbial Growth (2 levels)

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Growth occurs at 2 levels:
1 - Growth at a cellular level with increase in size
2 - Increase in population

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Binary fission process

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Parent cell enlarges, duplicates its chromosomes, forms a central transverse septum dividing the cell into 2 daughter cells

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Fission cycle is also known as what?

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Generation time

Front 71

Rate of population growth (3 points)

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Time required for a complete fission cycle = generation/doubling time.
Each new fission cycle increases the population by a factor of 2.
Generation times vary from minutes to days.

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Generation time: The number of cells in each generation is expressed as ?

Back 72

a power of 2.

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The number of generations is the ?

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Exponent

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Each cell in a generation produces how many cells?

Back 74

2 cells

Front 75

If an organism has a short generation time, then it is ?

Back 75

More communicable

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Generation time scenario:
If a bacterium reproduces every 10 minutes, how many cells would you have at the end of 1 hour?

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Solution: 64 cells
2^6 = 64
64 cells

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Scenario 2: If you had 4 million cells on a piece of chicken....how many would you have at the end of 1 hour? 2 hours? If you had generation times of 20 minutes?

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Solution;
a. 2^3 = 8
8 x 4 mil = 32 mill
b. 2^6 = 64
64 X 4 mill = 256 mill

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Bacteria STOPS growth at what temperature?

Back 78

10 degrees centigrade

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Population Growth Curve Stages (4)

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Lag phase
Exponential growth phase
Stationary phase
Death phase

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Lag phase

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"Flat" period of adjustment, enlargement; little growth

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Exponential growth phase

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A period of maximum growth will continue as long as cells have adequate nutrients and a favorable environment

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Stationary phase

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Rate of cell growth equals rate of cell death caused by depleted nutrients and O2, excretion of organic acids and pollutants.

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Death phase

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As limiting factors intensify, cells die exponentially

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Methods of Analyzing Population Growth

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1. Turbidometry (most simple)
2. Viable Cell Count
3. Direct cell count

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What is turbidometry?

Back 85

Degree of cloudiness (turbidity) reflecting the relative population size.

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What is Direct Cell Count?

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Counting the number of cells microscopically.
- Use a cytometer (no distinction between dead/live cells)
- Coulter counter - electronically scansa culture as it passes thru tiny pipette.
- Actual count from petri dish using a chart

Front 87

An organic nutrient essential to an organism's metabolism that cannot be synthesized itself is termed a/an ?

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Growth factor

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Source of the necessary elements of life is ?

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An inorganic environment reservoir

Front 89

An organism that can synthesize all its required organic components from CO2 using energy from the sun is a....?

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Photoautotroph

Front 90

An obligate halophile requires high what?

Back 90

Salt

Front 91

Chemoautrotrophs can survive on _____ alone.

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Minerals and CO2

Front 92

Which of the following statements is true for all organisms?

Back 92

They require inorganic nutrients.

Front 93

A pathogen would most accurately be described as a ?

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Parasite

Front 94

Which of the following is true of passive transport?

Back 94

Requires a gradient

Front 95

A cell exposed to a hypertonic environment will _____ by osmosis.

Back 95

Lose water.

Front 96

Active transport of a substance across a membrane requires ?

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ATP expenditure

Front 97

Psychrophiles would be expected to grow ?

Back 97

At refrigeration temperatures.

Front 98

Superoxide ion is toxic to strict anaerobes because they lack what?

Back 98

Dismutase

Front 99

The time required for a cell to undergo binary fission is called the ?

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Generation time

Front 100

In a viable plant count, each _____ represents a _____ from the sample population.

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Colony/Cell

Front 101

The stage in population growth with the highest rate of cell division is the ?

Back 101

Log phase

Front 102

Extremophiles are most commonly what type of microorganism?

Back 102

Archae

Front 103

Substances required by living organisms in relatively large quantities and which play principle roles in cell structure and metabolism are known as what?

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Macronutrients

Front 104

Which of the following defines a heterotroph?

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An organism that must obtain its carbon in an organic form.

Front 105

Molecules that satisfy heterotrophic nutritional requirements include all but which of the following? (Water, Lipids, nucleic acids, carbs, proteins)

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Water

Front 106

Nitrogen is required for the production of what category of molecules?

Back 106

Nucleotides

Front 107

The primary sources of nitrogen for heterotrophs include all except which of the following? (Proteins, DNA, RNA, Glucose, Amino acids)

Back 107

Glucose

Front 108

What nutritional category of microorganisms plays an important part in recycling inorganic nutrients?

Back 108

Chemoautotrophs

Front 109

The principal energy-yielding reaction in animals, most protozoa and fungi, and aerobic bacteria is known as what?

Back 109

Aerobic Respiration

Front 110

The earth would gradually fill up with organic material, and nutrients would not be recycled if it were not for what group of organisms?

Back 110

Saprobes

Front 111

The more successful of the parasitic microorganisms have what type of effect on their host?

Back 111

They have no fatal effects on the host and eventually evolve to a less harmful relationship with the host.

Front 112

Osmosis requires that a membrane have what property?

Back 112

Be selectively permeable to molecules other than water

Front 113

The most stable environment for cells exists in what type of solution

Back 113

Isotonic

Front 114

What is not a feature inherent in active transport systems?

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They form energy during transport.

Front 115

For most microbes, environmental factors fundamentally affect the function of what?

Back 115

Enzymes

Front 116

How is Taq polymerase from Thermus aquaticus able to function when used in the polymerase chain reaction?

Back 116

Its a heat-stable enzyme.

Front 117

What form of oxygen is not toxic to microorganisms?

Back 117

O2

Front 118

Which of the following describes anaerobic organisms?

Back 118

They lack the enzymes that use oxygen in metabolism and they lack the enzymes that process toxic oxygen products.

Front 119

Microorganisms that are sometimes found growing in jellies, syrups, and brines are known as what?

Back 119

Osmophiles

Front 120

Bacteria divide by a process known as what?

Back 120

Binary fission