chap 4 Flashcards
how microbes grow
bacterial growth refers to
increase in population (not size)
direct counting and examples
count cells
with microscope, flow cytometer, spread plate, pour plate, filtration
viable direct counting methods
Spread plate and pour plate
indirect counting (mass or density)
weighing, spectrophotometry, genome amount
flow cytometer
fast, automated, living and dead cell sorter, total particle count,
analyzes: size, shape, topography, complexity, and sorts
serial dilution
used to create a plate with countable colonies, 30
and 300 colonies per plate, for viable direct counting
weighting cells reserved for
mold and filamentous bacteria
spectrophotometry
bacteria scatter light (more scattering, more bacteria)
measured in OD (optical density)
Spectrophotometry is used on - amounts of bacteria
large
4 bacteria phases of growth
lag, log/exponential, stationary, death
lag phase
bacteria get used to new environment, population undergoes metabolic activity
exponential phase
divides a shit ton
stationary
slowed growth rate, nutrients exhausted, death rate and growth rate balanced
death phase
deaths exceed growth
endospores
resting cells, stationary, highly resistant, made when nutrients are low, not reproduction
sporulation
endospore formation
Germination
spore returns to vegetative state
endospores produced by
bacteria
bacillus (yea idk) , clostridium (diff and botulism)
balanced growth
cell increases by the same proportion over any interval of time
chemostat
allows for log growth, used for long experiments, growth rate dependent of medium amount, cell density is constant
large scale industrial fermentation is done in
chemostat
the faster the cell grows,
the bigger the cell, more ribosomes, RNA, Protein, and DNA
Extremophiles condition examples
temperature, hydrostatic pressure, osmotic pressure, pH, oxygen, radiation
temperatures impact of microbial growth
membrane permeability and enzyme stability
max growth temp
highest temp microbe will grow
protein stability (thermophiles)
charged amino acid on surface to be stable, has mechanisms to correct (chaperons and heat shock proteins)
DNA stability adaptions (thermophiles)
positive supercoiled DNA, high mg, more DNA binding proteins
membrane stability adaptions (thermo)
special lip membranes, isoprenoids, ether bonds, bi/monolayer
decimal reduction time/ d value
time that 90% of population is killed
low temperature shift effect on microbe
may be lethal
hydrostatic pressure
pressure caused by going deeper into the ocean
barotolerant
high pressure tolerance
piezophiles
need high pressure
peizophiles/baro mods
Unsaturated fatty acid, pressure resistant proteins, super negative supercoiled DNA
osmotic pressure
pressure to remove water from cell, salty, hypertonic
facultative halophiles
tolerates osmotic pressure, wants high salt concentration
obligate halophiles
need high osmotic pressure to grow like high salt, hypertonic
acidophiles
ph below 5
ex molds and yeast
alkalophiles
ph 8.5 to 11.5
buffers to maintain pH
phosphate salt, peptone, amino acids
Obligate aerobes
require oxygen
Facultative anaerobes
can use oxygen, will use anaerobic respiration when needed
microaerophile
aerobic, need less than oxygen than in air tho
superoxide dismutase (SOD)
converts superoxide radicals to molecular oxygen and hydrogen peroxide
catalase
antioxidant enzyme, aerobic hydrogen peroxide to water and oxygen
clostridium perfringens
causes gas gangrene
obligate anaerobe can be pathogens
true
radiation damages cells by
cleaving bonds, abnormal bond formed, o2 radicals
radiation resistant adaptation
multiple chromosome copies, strong DNA repair system
gram negative cell division
envelope constriction at mid cell
gram positive cell division
divison spetum
binary cell division
protoplasm doubled and then the cell is split
FtsZ
introduced Z ring (partition)
FtsZ is used inwhat organisms
most prokaryotes, chloroplast, mitochondria
alternates to fission
budding, progeny cell generation, diameter increase and longitudinal divide
budding
uneven break for cellular divisions
ex. yeast
progeny cells sticking
new cells generate, but don’t split
ex streptobacili
colony-forming unit
visible bacterial colonies on solid media
Turbidity
count bacteria by the clarity of the liquid, measures as optical density (form viable organisms)
Turbidity testing procedure
shine a light on test tube of microbes and measure the % of transmission
Turbidity faults
won’t detect contaminants
plasmolysis
plasma shrinks and cell loses water in a hypertonic environments
(salt or sugar)
microscope direct counting
requires dense cultures, cells/area (proportional to volume), counts living and dead cells
pour plate
microbe is melting into the medium and swirled
spread plate
microbe is introduced to medium and spread
flitration counting
for lakes and shit, water passed thru filter and then its cooked up, detects shit
Psychrophile
ideal growth temp is 5C
mesophille
ideal growth temp is 37C
hypertherophile
ideal growth at 80C +
food preservation red zone
20C-50C
what pressure is used to preserve food
osmotic (draws water out so bacteria cannot grow)
normal bacterial ph grow range
7.4-8
obligate anaerobes
oxygen bad
catalase and superoxide dismutase
enzymes that reduce toxic oxygen compounds
why could oxygen be toxic
strong asf reducing agent
superoxide radical, hydrogen peroxide, and hydroxyl
radical: oxidizing agents that destroy cell components
binary cell division steps
The cell grows, DNA is copied during replication,
The cell forms a new septum, splits
