Ch 6 - Microbial Nutrition and Growth

what 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