Unit 2: Chapter 6 Bacterial Growth, Nutrition, And Differentiation Flashcards
What are essential nutrients?
They are substances bacterial cells require for growth but must acquire from their environment. Many bacteria require only elemental building blocks to produce all chemical compounds required for life.
What are elements that are essential?
- Carbon
- Nitrogen
- Phosphorus
- Hydrogen
- Oxygen
- Sulfer
- Magnesium
- Iron
- Potassium
- Trace elements (needed in small amounts) such as cobalt, copper, and zinc
What are growth factors?
Growth factors are compounds that cannot be made by the organism, so they must be added to the culture media before they will grow
What are carbon compounds?
- they are esential for all forms of life
- are used as food, which stores energy and is a source of cellular building material for making biomass
Autotrophs
Carbon source for biomass
Make their own carbon compounds started with CO2
CO2 is fixed and assembled into organic molecules
Heterotrophs
Carbon source for biomass
Obtain carbon compounds from other ogranisms
Acquired from outside the cell
What is light and chemical compounds used as?
A source of energy by living things
T or F: Enegry is not an essential need for all forms of life
False; Energy is essential for all forms of life
Phototrophs
Energy source
Use light as an energy source
Chemotrophs
Energy source
Use potential energy stored in chemical compounds as an energy source
Lithotrophs
Electron source
Use inorganic chemical compounds
Organotrophs
Electron source
Use organic chemical compounds
Which essential nutrient is unavailable for use by most organisms?
Nitrogen (N2)
How do you make nitrogen into its usable form?
In order for nitrogen to become usable, it has to be “fixed” or converted to ammonium ions (NH4+) which is a form that can be used for biosynthesis.
What is a nitrogen-fixing plant symbiont that forms bacteria-filled nodules on roots?
Rhizobium
What is the nitrogen fixation process?
- Nitrogen is removed from the air and converted to ammonia by nitrogen fixers (rhizobium)
- Ammonia is converted to nitrate by nitrifiers (lithotrophs)
- Nitrogen is removed from nitrate and converted to nitrogen gas by denitrfiers (aerobic respires)
What precentage of nitrogen is in the air?
80%, but it is not useable
Culture Medium
- Nutrients prepared for microbial growth
- Have to be sterile (not contain living microbes)
Inoculum
Microbes introduced into medium
What are the two types of media?
- Complex media
- Chemically defined media
Complex Media
- Does not tell you the exact contents of the media
- Extracts and digests of yeast, meat, or plants
Eg; Nutrient broth/ Agar
Chemically Defined Media
Exact chemical composition is known
Which type of media is used when the bacteria needs special nutrients?
Chemically defined media
Agar
- complex polysaccharide
- used as solidifying agent for culture media in petri plates and slants
- generally not metabolized by microbes
At what temperature does agar become a liquid?
100 degrees C
At what temperature does agar become a solid?
~ 40 degrees C
What are the two media types?
- Selective media
- Differential media
Selective media
Compounds in the media prevent some type of bacteria from growing, favoring the growth of one specefic type
Differential media
Compounds in the media are metabolized differently which allows you to have many different growth types
What is a culture?
It is an artifical growth envrionment
What must be provided so that bacteria can grow in a culture?
The natural envrionment of the bacteria
Things such as:
1. Nutrition
2. Growth temperature
3. pH
4. Pressure
5. Osmotic Balance
6. O2 and other gasses to serve as electron acceptors
Bacterial growth is measured at the
population level
What is growth rate?
It is a measyure of the number of cells in a popualtion over time
How do most bacteria reproduce?
By binary fission
T or F; binary fission can be symmetrical or
asymmetrical
True
How do eukaryotic microbes divide?
by mitosis
What is generation time?
- The time required to carry out the whole binary fission process
- Time can vary
- It may also tell you how quickly you might develop symptoms depending on immune response
Binary Fission Steps
Just a picture
Arithmetic vs. Exponential Plotting
Picture from the powerpoint
What is the bacterial growth curve?
It shows the change in growth rate over time
Growth Cycle Phases
- Lag Phase
- Log Phase
- Stationary Phase
- Death Phase
Growth Cycle: Lag Phase
- Bacteria are preparing their cell machinery for growth
- Cells are not currently growing in this phase
Growth Cycle: Log Phase
- Growth approximates an exponential curve (straight line, on a logarithmic scale)
- This is the phase where you want to try to kill the bacteria because it is able to absorb everything in this phase
Growth Cycle: Stationary Phase
- Cells stop growing and shut down their growth machinery while turning on stress responses to help retain viability
- The number of cells dividing equals the number of cells dying
- Develop reistance to antibiotics and host defenses
1. make endospores
2. thicken cell walls
3. form capsules
4. fight for nutrients
5. have flagella move them to a more desirable location
Growth Cycle: Death phase
- Cells begin to die at an exponential rate
T or F; Dying cells can provide nutrients to other cells
True
Do bacterial cells every completely die off?
No, they do not completely die
Batch Culture/ Closed System
Carries out fermentation with a limited amount of nutrients
Continuous Culture/ Open System
Continuously carries out fermentation and is constantly providing nutrients, medium, etc
In addition to food, bacterial growth considerations include:
- Temperature
- Pressure
- Osmotic Balance
- pH level
ALL bacteria require these physcial conditions for growth
T or F; bacteria all require the SAME physiologic conditons
False; “Normal” physiologic condtions vary in differnt types of bacteria
Growth vs Tolerance
- Tolerance: Conditions in which the organisms can survive, but CANNOT grow
- Growth: Conditions that allow for the organsim to growth; end in “-phile”
Minimum Growth Temperature
The lowest temperature that permits a microbes continued gwoth and metabolism
Optimum Growth Temperature
- The temperature that allows the fastest rate of growth and metabolism
- “-phile”
- This is where you get max amount of growth
Maximum Growth Temperature
The maximum temperature at which growth and metabolism can proceed
Growth Rate with Temperatures
Just a picture
Psychrophile
- Most abundent
- Cold loving
- Optimal growth at cold temperatures
- Inhabit snowfields, polar ice, and the deep ocean
- Dies by ~20C
Thermophiles
- Grows best at higher than normal temperatures
- Live in soil and water associated with volcanic activity, compost piles, and in habittats directly exposed to the sun
- Survive in thermal springs
Hyperthermophiles
- Grows best at extreme temperatures between 80-120C
- Extreme Thermophiles
- Survive in thermal springs
Mesophiles
- Grows best at moderate temperatures
- Inhabit animals and plants as well as soil and water in temperate, tropical, and subtropical regions
What are most diease causing organisms?
Psychrophile, thermophiles, hyperthermophile, or mesophile?
Mesophile
Temperature Chart
Just a picture
What are thermophiles/ hyperthermophiles made of?
- Saturated fatty acids
- Long carbon chains
- Solid @ room temperatures
What are psychrophiles made of?
- Unsaturated fatty acids
- Short carbon chains can move easily
- Liquid @ room temperatures
Barometric Pressure
Barophiles are able to survive at a very high barometric pressure
Water Activity
This is how water availability is measured and is approximated by concentration
What does interactions with solutes (NaCl) do to water activity?
It lowers it
Lowered bc the amount of avaliable water is decreased
Osmolarity
This is a measure of the number of solute molecules in a solution
Hypertonic envrionments cause
plasmolysis
Shirnkage of the cell/ dehydration
Extreme or Obligate Halophiles
require high salt concentrations
Will pump Na out the cell if needed
Facultative Halophiles or Halotolerant
tolerate high salt concentrations
Will pump Na out the cell if needed
How is salt pumped out of the cell?
Via active coupled transport
Na+ is pumped out of the cell while K+ (compatable solute) is pumped into the cell
How does pH influence the growth of bacteria?
It influences the growth by altering the protein shape, which in turn changes protein activity
At what pH do MOST bacteria grow in?
pH 6.5-7.5
At what pH do molds and yeasts grow in?
pH 5-6
Microbes have adapated to inhabit diverse pH envrionments from
0-11.5
Acidophiles
Organisms that thrive under highly acidc envrionments
pH 0-5
Neautralophiles
Organisms that thrive under a more neutral envrionment
pH 6-8
Alkaliphiles
Organisms that thrive under more alkaline (basic) envrionments
pH 9-14
pH Chart
Just a picture
Acidic Condition
- Increase in concentration of H+ ions
- H+/K+ antiport transport system
- Pump out H+ and bring in K+
Buffering System
dont study this card until verified
- Urease changes urea to NH3 (ammonia)+ CO2
- Causes body to nutrealize the envrioment
How do certian bacteria such as E.coli prevent from becoming too acidic?
It can reverse proton influx by importing a variety of cations such as K+ and Na+
What does the cell do under extremely alkaline condtions?
The cells can use Na+/H+ anti-porters to recruit protons into the cell in exchange for expelling Na+
Na+ out the cell; H+ in the cell
How does the reactive oxygen species occur?
It occurs when O2 takes on the e- too early in th electron transport chain
Which type of organisms are able to destory reactive oxygen species (ROS)?
Aerobes or anaerobes?
Aerobes
The terminal electron acceptor of anaerobes are not O2
Which enzymes help aid in destroying ROS?
- superoxide dismutase
- peroxidase
- catalase
What dose superoxide dismutase remove?
superoxide
What does peroxidase remove?
hydrogen peroxide
What does catalase remove?
hydrogen peroxide
Destruction of ROS
Just a picture
Strict Aerobes
- Appear at the top of the tube
- Requires oxygen for energy metabolism and survive only in envrionments with oxygen
- Successfully detoxify reactive oxygen species (ROS)
- Include ALL groups of life; other than bacteria
Strict Anaerobes
- Appear at the very bottom of the tube
- Does not requires oxygen for energy metabolism and can only survive in envrionments without oxygen
- May also use fermentation; O2 not final e- acceptor
- Unable to detoxify ROS which makes oxygen toxic
- Include BACTERIA ONLY
Microaerophiles
- Aerobic, but ROS can be toxic; they make very little enzyme
- Survive in envrionments with lower oxygen concentration
- Appear to be in the middle of the tube
Aerotolerant Anaerobes
- Appears all over the tube
- Tolerates O2, but it prefers and is ultimately anerobic
- Has the ROS system in pace to be able to destory theml; usually lack catalase
Facultative Anaerobes
- Appears all over the tube
- Aerobic AND anaerobic
- Can survive with or without oxygen
- Has ROS enzymes
- Can do both fermentation and aerobic respiration
Facultative Aerobes
- Appears mostly at the top of the tube, but can be everywhere
- Will switch to fermentation if O2 is not present, but prefers O2 envrionment
Aerobe vs. Anaerobe in Tube
Just a picture
What are two ways to culture anaerobes?
- Anaerobe jar
- Anaerobic chamber
Anaerobic Jar
O2 is removed and CO2 is generated
Anaerobic Chamber
The glove ports remove the atmosphere via vacuum and replace it with a precise mixture of N2 and CO2 gases.
Biofims
- Surface attache communitities
- Most can grow in these
- Can be multi or single species
- Go where it is nutrient rich
- More resistant to antibiotics
Quorum Sensing
How cells are able to communicate and coodinate actions
Biofilm Formation Steps
Endospores
- Gram+ bacteria
- Dormant structure that requires no nutrient or energy
- Can last a very long time before reactivation may occur
