Unit 4 Lab Exam Flashcards
How do heterotrophs get carbon
from organic compounds
How do autotrophs get carbon
CO2
What are common carbon energy sources in this class
sugars–glucose or lactose
amino acids and peptides
organic acids, polyols, or alcohols–citrate, fatty acids, succinate or glycerol
What can supply nitrogen
amino acids, inorganic ammonium or nitrate salts
What can supply sulfur or phosphorus
inorganic salts such as magnesium sulfate or potassium phosphate
Define growth factor
specific organic compound that is required by a particular organism, as it cannot be synthesized by that organism
Organisms termed ________ tend to require a variety of growth factors
fastidious
What does a defined medium mean
the exact chemical composition of a culture medium is known
What does complex medium mean
the exact chemical composition is not known; and such a medium is often prepared from complex materials such as tissues or infusions
Define rich medium and our primary e.g.
when a medium contains an abundance of nutrients of all types; NB
Liquid media AKA ______ contain all the needed nutrients and is generally used to grow microbes through tubes and flasks
broth
What is the most common solidifying agent added to a liquid medium to become solid
agar
What is the purpose of buffers
chemicals that are incorporated to maintain a favorable pH range of the medium during growth
E.g. of buffers
sodium and potassium phosphate
calcium carbonate
peptones
extracts are used as a source of ______ _______
amino acids
peptones contain _______ and single __ ______
peptides; amino acids
e.g. of peptones
tryptose, tryptone, proteose peptone, peptone
peptone solutions will support the growth of ______ organisms because of what
many; the source of amino acids
Define pH indicator
a pH indicator is often added to differential media to detect pH changes in the medium
What are e.g. of pH indicators
brom cresol purple, brom thymol blue, phenol red
What color will the indicators turn if it is acidic
yellow color
What color does neutral red turn at acidic pH
red
What is a reducing agent
certain chemicals may stimulate growth by reducing the oxidation-reduction potential in the environment
e.g. of reducing agents
Cysteine and thioglycolate
what is a selective agent
antimicrobial agens can be employed in selective media to suppress or inhibit the growth of certain groups of microbes while allowing growth of desired organisms
Do selective agents kill unwanted organisms?
no
what is rich media
provides excess nutrients over the minimum require
What is the use of rich media
used when microbe is fastidious or we want more rapid growth
What is the use of defined media
physiological studies of organisms for determining the exact nutritional needs of an organism
What is non selective medium
it doesn’t deliberately support the growth of one microbe over the other (allows many to grow)
What is the use of non selective medium
growth of a wide variety of organisms
What is the use of selective medium
isolation and growth of a specific culture type of microbe from a mixed culture
What is all purpose medium
non-selective, supports a wide variety of organisms
What is differential medium
contains ingredients that allow us to visually differentiate between different types of microbes
What is the use of differential medium
visual identification of a type of microbe based on colony appearance
What are e.g. of all purpose rich, complex medium
PCA, NA, Yeast extract tryptone glucose
What is the difference between enrichment media and selective media
enrichment media are those that favor the growth of certain microbes
selective media supports the growth of desired organism while inhibiting the growth of many of the unwanted ones
What are examples of selective media
MAC
nitrogen free broth
succinate broth
azide containing media
What are the selective ingredients in MAC
bile salts and CV that inhibit most gram positive bacteria
What are e.g. of differential media
MAC and EMB
What type of growth will obligate aerobes have
growth at the top of the tube where there is oxygen
What do obligate aerobes grow in
posses only a respiratory type of metabolism and use oxygen as the terminal electron acceptor
Where will obligate anaerobes grow
at the bottom of test tubes
What do obligate anaerobes need to grow
02 is toxic so they need to be away from it
How to facultative anaerobes grow
prefer O2 but can grow without it
how do aerotolerant anaerobes grow
prefer no O2 but can grow with it
Where will anaerobic respirers grow
no growth at all in the tube
If fermentation occurs in a neutral pH with the color purple to begin what color will it turn
yellow
Are MAC and EMB sharing the following features
contain pH sensitive dye ingredients
inhibits the growth of gram negative bacteria
differential for glucose fermentation
contain peptone as a nitrogen source
T
F
F
T
How does fermentation work
make ATP using only substrate level phosphorylation as a method
Does fermentation produce large amounts of waste products
yes
What is respiration
making ATP using the ETC and proton motive force
What are the examples of selective media that help determine physiological characteristics
glucose fermentation
motility
Thioglycolate
EMB agar
For MAC what ingredients are selective agents
bile salt and CV
For MAC what ingredients are differential agents
neutral red and lactose
What bacteria type is inhibited by the bile salts and CV in MAC
gram positive
What color does MAC look when fermentation has occured
red
How long can MAC be incubated for
24 hours
Mobility has occurred when microbes can move ________ the line of inoculation
away
Mobility can be seen when a tube has _________-
turbidity
What type of bacteria does EMB agar detect and identify
enteric bacteric
What does the Eosin Y and Methylene blue dyes inhibit
gram positive bacteria and dyes combined with lactose allow for differentiation between lactose fermenters and lactose non-fermenters
With the NA agar, what did…look like
E. coli
P. fluorescens
S. epidermidis
milky color, irregular colony, undulate, smooth
yellow color, irregular colony, undulate, rought
white color, circular, entire edge, smooth
What bacteria had no growth in the MAC
E. coli
P. fluorescens
S. epidermidis
S. epidermidis
