NRSG 205 Chapter 6 - Microbial Growth

Lipases

break triglycerides down into glycerol and fatty acids

Triglyceride makeup

glycerol molecule with 3 fatty acids

Glycerol makeup

carbon chain attached to hydrogen atoms and OH groups

Fatty acid makeup

carbon chain attached to hydrogen atoms and OH groups

Beta-oxidation

breaks down fatty acids 2 carbons at a time and releases energy

Proteases

break down proteins into amino acids

2 functions of amino acids (besides forming proteins)

1. Conversion to citric acid cycle intermediates

2. Conversion to acetyl-CoA (or other amino acids)

In what 3 ways an amino acids be converted to acetyl-CoA (or other amino acids)?

1. Transamination: moves amino groups

2. Decarboxylation: removes carboxylic acid

3. Desulfurization: removes sulfur group (if applicable) from amino acid

Amino acid structure

amino group (NH3), hydrogen, central carbon, carboxylic acid, and R group

How many R groups exist?

There are 20 R groups, resulting in 20 unique amino acids

Photosynthesis process

• Conversion of light energy to chemical energy

• Chemical energy is then used to fix carbon into molecules that can be used for cellular respiration

Do photosynthetic organisms have mitochondria, chloroplasts, or both?

Both

Phototrophs

photosynthetic organisms that create their energy from sunlight

Chemotrophs

use organic (and sometimes inorganic) chemicals to create energy

Autotrophs

get their carbon from carbon dioxide (inorganic)

Heterotrophs

get their carbon from organic molecules (i.e. carbohydrates)

Photoautotrophs

get their energy from photophosphorylation and get their carbon from carbon dioxide

Photoheterotrophs

get their energy from photophosphorylation and get their carbon from organic molecules

Chemoautotrophs

get their energy from inorganic compounds and get their carbon from carbon dioxide

Chemoheterotrophs

get their energy and carbon from organic molecules

Microbial growth

increase in a microbial population

3 requirements for microbial growth

1. Temperature

2. pH

3. Osmotic environment

3 types of organisms (in relation to temperature preferences)

1. Psychrophiles

2. Mesophiles

3. Thermophiles

Psychrophiles

cold-loving

Mesophiles

prefer a moderate environment (37ºC)

Thermophiles

heat-loving

3 types of growth temperatures for microorganisms

1. Minimum growth temperature

2. Optimal growth temperature

3. Maximum growth temperature

2 types of organisms (in relation to pH preferences)

1. Acidophiles

2. Alkalophiles

Acidophiles

prefer low pH

Alkalophiles

prefer high pH

For most bacteria, optimal pH falls between _____ and _____

6.5, 7.5

Do fungi have a slightly lower or slightly higher optimal pH than bacteria?

Lower

Plasmolysis

shriveling up of a bacteria cell in a hypertonic solution

Halophile

prefers hypertonic environments

5 chemical requirements for all living organisms

1. Carbon source

2. Nitrogen source

3. Phosphorus source

4. Sulfur source

5. Certain oxygen requirements

2 ways that nitrogen can be acquired by microorganisms

1. For protein and nucleic acid synthesis

2. Nitrogen can be acquired from breaking down proteins or fixing atmospheric nitrogen

2 uses of phosphorus in microorganisms

1. Nucleic acids

2. ATP

2 uses of sulfur in microorganisms

1. Many amino acids (like sulfur)

2. Vitamins

5 types of organisms (in relation to oxygen requirements)

1. Obligate aerobe

2. Facultative anaerobe

3. Obligate anaerobe

4. Aerotolerant anaerobe

5. Microaerophiles

Obligate aerobe

have an absolute need for oxygen

Facultative anaerobe

prefer oxygen, but can survive in absence of oxygen

Obligate anaerobe

cannot survive in the presence of oxygen

Aerotolerant anaerobe

prefer a lack of oxygen, but can survive in the presence of oxygen

Microaerophiles

low oxygen requirement

When can oxygen be poisonous?

If certain enzymes are not present

3 enzymes that ensure that oxygen is not poisonous

1. Superoxide dismutase

2. Catalase

3. Peroxidase

Superoxide dismutase function (and chemical equation)

converts oxidants into oxygen and hydrogen peroxide (2O-2 + 2H+ → O2 + H2O2)

Catalase and peroxidase function (and chemical equation)

converts hydrogen peroxide into water (H2O2 + 2H+ → 2H2O)

Biofilms

made of extracellular matrix and allows bacteria to live in communities on different surfaces

3 functions of biofilms

1. Allows adherence to surfaces

2. Protection from dessication (drying out)

3. Resistance to antibiotics

5 types of media

1. Chemically defined media

2. Complex media

3. Reducing media

4. Selective media

5. Differential media

Chemically defined media

exact chemical composition of the media is known

Chemically defined media function

Typically used to grow autotrophs

Complex media

exact chemical composition can vary slightly, but researchers still know the constituents

Reducing media

reduces or removes molecular oxygen from the media in conjunction with an anaerobic jar/chamber

Reducing media function

Typically used to grow obligate or facultative anaerobes

Selective media

allows for the growth of only desired microbes

Example of selective media use

gram negative bacteria will grow, but gram positive bacteria will not

Differential media

distinguishes different organisms

Example of differential media

MacConkey agar differentiates between E. Coli and salmonella

What must parasites and viruses be cultured in?

In a cell culture (not on a plate) or in living animals

Example of a bacteria that can be grown in a cell culture

Mycobacterium leprae

Capnophiles

organisms that require high carbon dioxide requirement

How are capnophiles cultured?

CO2 incubator or candle jar (burning of the candle releases CO2)

Binary fission causes what type of bacterial growth?

Logarithmic

How can the growth of bacteria be plotted?

# of cells vs. time

4 phases of bacteria growth

1. Lab phase

2. Logarithmic phase

3. Stationary phase

4. Death phase

Lab phase of bacterial growth

no growth but metabolic activity is high

Logarithmic phase of bacteria growth

bacteria multiply at their fastest rate and metabolic activity is high

Stationary phase of bacterial growth

growth rate is equal to death

Death phase of bacterial growth

carrying capacity has been reached, so death exceeds growth