Microbiology Unit 4 Prokaryotic Growth

pure culture

culture that consists of just one bacterial species

mixed culture

a variety of bacteria living in a mixed community amongst one another, they communicate and work together

Generation time

time it takes a cell population to double in number

Biofilm

community of microorganisms, that produce a extracellular, polysaccharide/polymer

Acidophile

bacteria that have evolved to grow in acidic environments

Alkalophile

bacteria that have evolved to grow in alkaline environments

What is the minimum number of bacteria cells required to form a colony?

10

Be able to describe the process of binary fission

Cell duplicates its chromosomes to form two identical sets, Cell form a wall down the middle separating the two sets of chromosomes, Cell splits into two separate identical daughter cells

Why do we say that binary fission is natural cloning?

binary fission is the process of creating two identical copies from one cell its a duplicate just like a clone

Why do microbes grow as mixed communities in nature?

resource sharing, creates a more resilient system, learn through others

What is the purpose of biofilms?

protects that bacteria within from environmental chemicals, antibiotics, makes the colony more resistant

What is the clinical significance if a biofilm?

From a clinical view biofilms are not good, because they are protected they are hard to get rid of, and when they get big enough cells may leak out to go form biofilms elsewhere in the body

Where in the body do biofilms tend to collect?

on the teeth, and medical devices such as catheters, or artificial joints

How can biofilms help us in the real world?

biofilms can be used in bioremediation to help clean up oil spills

Describe two methods for isolating pure cultures from a mixed culture.

Streak plate, spread plate

Describe the method of using a streak plate?

use a loop to take a sample of my specimen, and use my loop to spread them across the plate, to separate the individual cells

Describe the process of using a spread plate

use a small amount of liquid containing the bacteria, place it in the tray, and spread it out across the surface to hopefully separate the bacteria apart from one another

What is an open/ continuous system for growing bacteria?

nutrients are pumped in and waste is pumped out, bacteria is continuously growing and will have no stopping point till the system is shut off

What is a closed/ batch system for growing bacteria

nutrients are added, and not replaced, waste is not removed, the system is closed off to additions of subtractions once the reaction starts

What is the difference between an open/continuous culture and a closed/batch culture?

an open culture is constantly being added and subtracted from, and can go indefinitely, a closed system has no manipulation after the experiment starts and has an estimated life time.

When is a continuous culture used?

a continuous culture is used when wanting a stable growing environment for a long time, can be used in industry to produce large quantities of bacteria and proteins

What are different phases of a bacterial growth curve

lag, log, stationary, death, prolonged

What happens during the lag phase?

Molecules are adjusting to new environment, no growth happens

What happens during the exponential/log phase?

molecules are at their greatest growth

During what phase is growth rate calculated?

exponential/log phase

What happens during the stationary phase?

bacteria are dying at the same rate that new bacteria are being populated

What happens during the death phase?

cells are dying at a constant exponential rate

What happens during the prolonged decline phase?

gradual decrease in viable cells “fitter cells” emerge

List and describe the environmental factors that influence microbial growth.

growth temp, oxygen usage, pH

How are bacteria classified according to growth temperature?

based on temperature ranges, and optimal growth temperature

What is the difference between an organism’s optimal growth temperature and its temperature growth range?

The range is the minimum and maximum temperatures that a bacteria can grow in; the optimal growth is the exact temperature a bacteria reaches its fastest rate of growth

Why can’t bacteria grow at temperatures outside their range?

If bacteria are put in an environment below or above its min and max it won't grow

What happens if a bacteria is in too high of a temperature?

Its proteins will denature

What happens if a bacteria is in too low of a temperature?

its proteins will lose ability to flex, and bend

What are the different categories of bacteria according to temperature?

psychrophile, psychrotroph, mesophile, thermophile, hyperthermophile

What is a psychophile and its range?

love it cold, OGT 10 celsius, can grow below freezing found in the polar ice caps

What is a psychrotroph and its range?

can tolerate colder, prefer room temperature

What is a mesophile and its range?

can grow at room temp, prefer body temp, OGT 37 celcius

What is a thermophile and its range?

like it hot, OGT 70-80 Celcius

What is a hyperthermophile and its range?

like it above boiling, found in hydrothermal vents of ocean

Which category includes the majority of human pathogens?

mesophiles

How are bacteria classified according to oxygen requirements?

either as aerobes or anaerobes

What are the different ways aerobes are classified?

obligate, microaerophiles, facultative anaerobes, capnophiles

What is an obligate aerobe?

has an absolute dependence on oxygen metabolically, needs oxygen, can only do aerobic respiration, can detoxify oxygen by products

What is a microaerophile?

can use oxygen and respiration, but have a limited ability to detoxify, live in a reduced oxygen environment

What is a facilitative aerobe?

can do aerobic if oxygen is present and anaerobic respiration when oxygen is not present, has some enzymes to break down byproducts

What is a capnophile?

use oxygen metabolically, and break down byproducts, like an atmosphere high in CO2

What are the different ways anaerobes are classified?

obligate, and aerotolerant

What is an obligate anaerobe?

cant use oxygen in respiration, and don't have enzymes to detoxify, if exposed to oxygen the toxic products will kill them, can only survive in environments without oxygen

What is an aerotolerant anaerobe?

dont use oxygen in respiration, but have enzymes to break down by products, they can live in environments with oxygen they just cant use it.

What group of bacteria can use oxygen to produce energy?

aerobes

What group cannot use Oxygen for energy production?

anaerobes

Why aren’t aerobes killed in the presence of oxygen while obligate anaerobes are?

aerobes are not killed because they possess the enzymes to break down byproducts of oxygen use, well anaerobes do not

What enzymes help bacteria detoxify oxygen and what reactions do these enzymes catalyze? Catalize superoxide to hydrogen peroxide, to oxygen and water

Catalize superoxide to hydrogen peroxide, to oxygen and water

Why can’t bacteria grow outside their normal pH range?

They are evolved for their proteins to work in a specific range of pH, when outside of the pH their proteins will denature and won't function

What is the difference between an osmotolerant bacterium and one that is a halophile?

osmotolerate bacteria have defence against water loss when in hypertonic solutions, halophiles have defences against water gain on hypotonic solutions

Why is the growth of non-osmotolerant bacteria inhibited when placed in hypertonic solutions?

water leaves the cytoplasm, and the cell doesn’t have enough water to continue metabolic reactions, stenting its growth

What six elements are essential for all living organisms and what biological molecules are these elements used to make?

Carbon, Oxygen, Nitrogen, Hydrogen, Phosphorus, and Sulfur

What is a growth factor?

compounds required for growth

What are some examples of growth factors?

purines, pyrimidines, vitamins, amino acids

What term is used to describe bacteria that require the addition of growth factors in order to grow?

Fastidious

What is Fastidious bacteria

bacteria that require additional growth factors to grow

What is the energy source of phototrophs?

uses sunlight

What is the energy source of chemotroph?

uses chemicals

What is the energy source of lithotrophs?

inorganic compounds

What is the carbon source of autotrophs?

carbon dioxide

What is the carbon source of heterotrophs?

organic compounds

What is the carbon and energy sources of photoautotrophs?

energy from sunlight, CO2 for carbon

What are the carbon and energy sources of photoheterotrophs?

sunlight for energy, organic compounds for carbon

What are the carbon and energy sources of chemolithoautotrophs?

inorganic compounds for energy, CO2 for carbon

What are the carbon and energy sources of chemoorganoheterotrophs?

Organic compounds for energy, organic compounds for carbon

What is complex growth media

composition is unknown, not exactly sure of its chemical makeup

What is enriched growth media

nutrient rich culture designed to promote the growth of fastidious microorganisms

What is chemically defined growth media

composition is known exactly

What is selective growth media

contains compound to inhibit growth of bacteria were not interested in but allows the bacteria we do want to observe to grow

What is differential growth media

able to visually see the difference between bacteria by growth characteristics such as pH indicator

What is selective differential growth media

inhibit and visually see different bacteria growths

Why is blood agar considered an enriched, differential medium?

it is enriched since it helps fastidious bacteria grow and differential since it surrounds those growths with a zone of visible red

List the methods discussed in class that are used to detect and measure bacterial growth

direct cell counting, membrane filtration, biomass detection, detecting cell products

What are the methods to direct counting?

counting chamber, coulter counters and flow cytometry

What methods measure both viable and non-viable cells?

direct counting, and detecting biomass

What methods measure just viable cells?

plate count, membrane filtration

For what types of samples is membrane filtration used?

sample with low number of bacteria

What method detects changes in cell biomass?

total cell weight (wet vs dry weight) and turbidity

What is turbidity and how is it measured?

cell density measured with a spectrophotometer

What is the relationship between cell density and turbidity?

as density increases turbidity increases