Studied by 1 personwhat does growth refer to in an organism
increase in size of organism
what does growth refer to in microbes
an increase in the population size
how do bacteria reproduce
asexually through binary fission
how do eukaryotic cells reproduce
through mitosis
how do yeast cells reproduce
asexually through budding
what is a a batch culture
it means theres only so much nutrients available for the bacteria to take in
what are the phases, in order, for the bacterial growth curve
lag phase, log phase, stationary phase, and death phase
what is the lag phase
the introduced number of bacterial cells are gearing up for replication
what is the log phase
the bacterial cells are reproducing
what is the stationary phase
the bacterial cells begin to run out of nutrients and are giving off by-products
what is the decline phase
the cells die, but their are some viable cells for a few days
what does the slope of the log phase tell us
the growth rate
what does the slope of the death phase tell us
the death rate
the slopes from the bacterial growth curve should be the ________, just one ___________ and one ________________
same, positive, negative
what two ways do we get bacterial cells to a way that we can count
serial dilutions and a standard plate count (SPC)
what is a serial dilution
diluting out concentrated bacterial cultures to get managable numbers or something we can count
what is a standard plate count (SPC)
counting the number of colonies after a serial dilution
what method do you use to determine the number of bacterial cells in a culture
a pour plate method
what is the acceptable range of colonies per plate for a pour plate when counting large colonies
30-300 colonies per plate
what is a viable count
the total number of live cells being counted at a given time
what are the two ways to preform a direct or total cell count
counting the isolated colonies or doing a cell count through cytometry
what is cytometry
it uses a machine that dilutes the cells so you can directly count them
what does an indirect count mean
you’re not looking for a number just at the gowth of colonies
what are the two ways you can indrectly count bacterial colonies
through turbidity or dry weight
how is tubidity used to indirctly count colonies
if the tube is cloudy then their are micribes growing in it
if their is not a lot of light shining through a tube that has tubidity in it what does that mean
their is high tubidity meaning the population size is larger
if their is a lot of light shining through a tube with turbidity in it what does that mean
their is low turbidity meaning the population size is smaller
what does dry weight measure in bacteria
the number of biomass in the colonies
what is a physical influence of microbial growth
temperature
what are the four types of microbes that grow at different temps
psychophiles, mesophiles, thermophiles, and extremthermophiles
what is the temperature range of psychrophiles
less than 20 degrees C
what type of microbes are psychrophiles
food spoilage because they live a fridge temperatures
what is the temperature range for mesophiles
15-45 degrees C with 37 C being optimum
what type of microbes are mesophiles
normal flora, pathogens, E. coli
why are mesophiles medically important
because they live at room temperature
what temperature do thermophiles live at
60 degrees C
what temperature do extremthermophiles live at
65-100 degrees C (near the point of boiling water)
what is an example of an extremthermophile
archaea
why do many pathogens not like to be warm
they become denatured
what is a chemical influence of growth
oxygen influences
what are the two categories of oxygen influences
aerobes and anaerobes
what is the difference between aerobes and anaerobes
aerobes is with oxygen anaerobes is without oxygen
what is an obligate aerobes
it thrives in our oxygen levels
what is a microaerophilic
likes smaller or lower amounts of oxygen
what are the two types of aerobes
obligate aerobes and microaerophilic
what are the three types of anaerobes
obligate anaerobes, facultative anerobes, and aerotlerant anaerobes
what is an obligate anaerobe
oxygen is toxic to them
what is a facultative anaerobe
it can grow without oxygen but can also grow with it
what is an aerotolerant anaerobe
it tolerates oxygen and can go without but doesnt use oxygen for anything
what are the two clinical anerobic bacteria
clostridium and bacteriocides
what is thioglycolate medium used for
it is a reducing agent that decreases the amount of oxygen so we can determine what type of microbe is present
where do obligate aerobes grow at in thioglycate medium
at the surface
where do microaerophiles grow at in thioglycate medium
below the surface but not very deep
where do obligate anaerobes grow at in thioglycate medium
only at the deep bottom part of the tube
where do facultative anaerobes grow at in thioglycate medium
all throughout the tube
what is a biofilm
a collection of mixed microbes trapped in the sticky solution called biofilm
what are some examples of a biofilm
dental plaque, pseudomembranes, and necrosis or flesh eating disease
what form of medication doesn’t normally work on biofilms
antibiotics
what is sibling warfare
when two line inoculations are prefromed on a plate and the microbe sbegin to grow away from each other
what is the point of using selective and differential media
to isolate and ID bacteria
certain microbes can be selective for what ______ they grow at
pH
fungi grow best at what pH levels
lower pH levels such as 5-6
bacteria grow best at what pH levels
closer to nuetral or even a little alkaline/basic
what type of medium is blood agar
enriched and differential
what is blood agar enriched with
RBC’s from sheep
how is blood agar differential
from hemolysis
what is carbohydrate fermentation used for
to determine different types of bacteria/charcteristics
what is glucose common in
many bacteria
what is lactose common in
enterics
what is mannitol common in
some staph bacteria
acid fermentators cause a ___________
low pH
if their is a low pH in the medium what is caused
a color change in the growth medium (ex from red to yellow)
what is a durham tube
a test tube that is in a liquid broth medium and is inverted and filled with the same medium, it there’s CO2 the interior tube will start to bubble
what is a candle jar used for
it reduces oxygen levels but doesn’t make the enviorment completely anerobic
what is an anerobe jar
it makes the enviorment completely anaerobic
what microbes is a candle jar used for
microaerophiles
what type of microbe is an anaerobe jar used for
obligate anaerobes such as clostridium and bacteroides
what does a candle jar, anaerobe jar, and thioglycate medium do
they control the oxygen levels in a microbes enviorment
viruses can not be cultured on _________________________
artificial media because there’s no cells
why do some bacteria require special growth media
because they are harder to culture
many bacteria are fastidious meaning
they have complex nutrient requirements
what type of media is used for fastidious bacteria
enriched media
what are the two types of enriched media
choclate agar and blood agar
what is chocolate agar
it is enriched with sheeps blood but the RBC’s are lysed and the released hemoglobin turns it a brown color
major bacteria used on enrched media
haemophilus influenzae and neisseria gonorrheae
what type of media is used for non-fastidious bacteria
general purpose media like nutrient agar
multipurpose media is divided into
primary isolation media and diagnostic media
what is primary isolation media used for
to isolate specific bacterial types, genera and species/strains
what are the two types of primary isolation media
selective media and selective/differential media
what is the function of selective media
it prevents the growth of some bacterial types while allowing growth of others
what are the two types of selective/differential media
EMB and MAC
what does EMB stand for
eosin methylene blue
what is EMB selective for
gram negative bacteria
what is EMB selective against
gram positive bacteria
what is EMB differential for
lactose fermentation
if their is a cloudy pink/red color on an EMB plate that means
the bacteria is lactose positive
if there is a green, metallic sheen on an EMB plate that means
there is strong lactose fermentation (ex E.coli)
what does MAC stand for
MacConkey
an MAC plate has the _________________________ as an EMB plate
same properties
what does lactose fermentation look like on an MAC plate
dark pink/red
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