Microbiology ch 7

acidophiles

alkalophiles

neutrophiles

acid-shock protein

proteins that bind to normal proteins to protect it from harm from acid

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Helicobacter pyri

Which have pH indicator?

MSA,

media buffer

Prevents ph in media from changing easily

Obligate aerobe

Need oxygen

Facultative aerobe

Prefer oxygen

What is an example of a falcultative aerobe?

E. coli

Aerotolerant anaerobe

ignore oxygen

Strict anaerobe

Oxygen is toxic

Microaerophile

< 2-10% oxygen, need a bit of oxygen, but not it’s atmospheric concentration

Classify bacteria based on oxygen requirement

terms above

What is the concentration of atmospheric oxygen?

20% or more

What are the protective enzymes that aerobes produce?

superoxide dismutase (SOD) and catalase

What happens to a protein or membrane that is oxidized?

It renders it nonfunctional or causes a mutation that causes the cell to die

Do

Cannophile

Require higher concentration of CO2

What are three examples of human pathogens?

Campylobacter, Haemophilus, Neisseria

Barotolerant

Can tolerate high atmospheric pressure

Barophilic

High-pressure loving organisms that require it for optimal growth

What are examples of Ionizing radiation?

X-rays and gamma rays

What factors have an impact on microbial growth?

Radiation, oxygen, CO2,

All life forms on the planet are adapted to…

visible light

What does ionizing radiation do?

It disrupts and mutates protein, DNA, membrane, and kills the organism

What protects from DNA radiation?

DNA repair molecules

What is the mechanism in which UV light causes damage?

formation of thymine dimers in DNA

What are the two mechanisms by which DNA can be repaired from damage?

Photoreactivation and dark reactivation

Photoreactivation

Splits the dimer in the presence of light

Dark reactivation

Excises and replaces damaged dimers (“T’s” like in example)

Can visible light cause problems? How?

Yes. Singlet oxygen ( 1 O2)

What protects (carrots) from singlet oxygen damage/ photooxidation?

Carotenoid pigments

Quorum sensing

communication among bacteria by chemical signaling

Complex media (all the media used in the lab)

Some ingredients are not known

Synthetic media

Defined media

Peptones

Name three media components

Peptones, extracts, and agar

General purpose media (in lab, nutrient agar/broth)

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Enriched media (blood agar)

General purpose media + component

What is an important agar for preventing the growth of gram positive bacteria in medical and environmental fields?

MacConkey agar (lactose vs non-lactose fermenters)

What’s the special incubator used to grow anaerobic bacteria?

Anaerobic incubator/jar/chamber

What are the techniques used to isolate pure cultures?

Streak plate, spread plate, and pour plate

Spread plate

Pour plate

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What is an advantage of pour plate technique?

bacteria can grow under surface/inside of agar — for bacteria that do not like oxygen/ oxygen-sensitive

Streak plate

Colony characteristics that develop when microorganisms are grown on surfaces….

Aid in identification

_______ is an increase in cellular constituents can result from: \n an increase in cell ________ (ex: when microorganisms reproduce by budding or binary fission) or an increase in cell _______ (ex: _______ microorganisms have nuclear divisions that aren't accompanied by cell divisions)

growth, number, size, coenocytic

cell cycle

sequence of events from formation of new cell through the next cell division

cell cycle

most bacteria divide by ______ ______

binary fission

the growth curve is observed when microorganisms are cultivated in _______ _______

batch culture

batch culture

culture incubated in a closed vessel with a single batch of medium

the growth curve is usually plotted as ________ of cell number vs. time

logarithm

lag phase

phase during which cell synthesizes new components (ex: to replenish spent materials; to adapt to a new medium or other conditions)

exponential phase

rate of growth is constant; population is most uniform in terms of chemical & physical properties during this phase

stationary phase

total number of viable cells remains constant

stationary phase may occur because metabolically active cells stop ________, and because reproductive rate is balanced by ______ rate

reproducing, death

what is the critical cell density?

10^9 cells/ml in bacteria

possible reasons for entry into stationary phase:


1. _______ limitation
2. limited _______ availability
3. ______ ______ accumulation
4. critical population _______ reached

nutrient, oxygen, toxic waste, density

starvation responses:

* _______ changes (ex: endospore formation)
* decrease in _______, protoplast ______, and nucleoid ________
* production of starvation _______
* ______ term survival
* increased ________

morphological, size, shrinkage, condensation, proteins, long, virulence

death phase

cells dying at exponential rate

death phase

irreversible loss of ability to reproduce

in some cases, death rate slows due to accumulation of _______ cells

resistant

During the _____ phase, the bacteria adapt themselves to growing conditions and synthesize RNA, enzymes as well as other molecules. The _____ phase is when the bacteria grow very rapidly. The _______ occurs when a nutrient is depleted in the environment so death and growth is equal. The ______ phase is when the bacteria die due to lack of nutrients.

lag, log, stationary, death

generation time

time required for the population to double in size

mean growth rate constant

number of generations per unit time

mean growth rate constant is usually expressed as _______ per _______

generations, hour

measurement of microbial growth can measure changes in number of _______ in a population and can measure changes in _______ of population

cells, mass

what are the 2 types of measuring cell numbers?

direct and viable cell counts

direct cell counts

includes counting chambers, electronic chambers, and membrane filters

viable cell counts

includes plating methods and membrane filtration methods

useful for counting both eukaryotes and prokaryotes

counting chambers

T/F counting chambers can't distinguish living from dead cells

True

electronic counter

microbial suspension forced through small orifice

movement of microbe through orifice impacts _______ _______ that flows through orifice

electric current

electronic counters count instances of ________ of current

disruption

the coulter counter is an example of what type of cell number measuring device

electronic counter

cell number measuring device that's useful for large microorganisms and blood cells, but not prokaryotes

electronic counters

T/F electronic counters can distinguish living and dead cells

False

cell number measuring device in which cells are filtered through a special membrane that provides dark background for observing cells

membrane filters

in membrane filters, cells are stained with _______ dyes

fluorescent

membrane filters are useful for counting _______

bacteria

with certain ______, membrane filters (can/cannot) distinguish living from dead cells

dyes, can

measures the number of viable cells

plating methods

CFU

population size is expressed as

planting methods

widely used for viable counts of microorganisms in food, water, and soil

clump

inaccurate results in plating methods can be obtained if cells _______ together

membrane filtration

cell counting method that's especially useful for analyzing aquatic samples

dry weight, quantity, constant, turbidometric measures

measurement of cell mass:


1. _______ _______ - time consuming and not very sensitive
2. _______ of a particular cell constituent - (ex: protein, DNA, ATP, or chlorophyll); useful if amount of substance in each cell is _______
3. ________ _______ (light scattering) - quick, easy, and sensitive

nutrients, removal

growth in an open system has continual provision of _______ and continual ________ of wastes

log

continuous culture maintains cells in the ______ phase at a constant biomass concentration for extended periods

continuous culture

continuous culture is achieved using a _______ _______ system

chemostat

\n

in a ________, the rate of incoming medium = rate of removal of medium from vessel

chemostat

in the _______, an essential nutrient is in limiting quantities

regulates the flow rate of media through vessel to maintain a predetermined turbidity or cell density

turbidostat

no

does the turbidostat have a limiting nutrient?

\n

1. exponential
2. low
3. interactions, aquatic
4. food, industrial

importance of continuous culture methods:


1. constant supply of cells in ______ phase growth at a known rate
2. study of microbial growth at very _______ nutrient concentrations, close to those present in natural environment
3. study of ________ of microbes under conditions resembling those in _______ environments
4. _______ and _______ microbiology

extremophiles

grow under harsh conditions that would kill most other organisms