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define differential medium
growth medium that allows two or more organisms to be distinguished from one another by some parameter, such as growth vs. no-growth, distinguishing colors, distinguishing morphologies, etc
the fermentable carbohydrate in lysine iron agar is dextrose glucose
is dextrose glucose
the primary substrate for deamination and decarboxylation reations in this expirement is
the ph indicator in this medium is
is purple at ph 6.8 or higher and yellow at ph 5.2 and bellow
thiosulfate when reduced becomes
ferric iron ion in this expirment reacts with hydrogen sulfide to form
black drecipitate oxygen
this medium provides an oxygen zone for growth on the slant and
no oxygen zone (anaerobic) for growth in the butt
bile esculin agar is both a selective and differential medium
selective growth medium that favors growth of one group of micro organisms inhibits or prevents growth to others
differential growth media contains an indicator usually color to detect the presence or absence of a specific metabolic activity
what is a presumptive identification of a micro- organism
tentative identification of an isolate based on one or more key test results
esculin is an example of a type of molecule known as a glycoside its 2 components are the sugar _____ and a compound called ____
the bile in bile esculin agar inhibits the growth of most ____ organisms
what is the bile in bile esculin agar
when esculin molecules are split by bacteria _____ reacts with ferric citrate and forms a ____ color phenolic iron complex
describe a positive result in this experiment including time frame
48 hours enterococcus faccalis is positive and tunrs esculin into esculetin the escultin reacts with iron and produces a black color giving it a positive
describe a negative results in this expirment indcluding time frame
citrobacter freundii is negative because it cant hydrolze esculin
explain how bile esculin agar acts as a differential medium
because it contains ferric ammonium citrate to practice the black color and the bile inhibits the growth of the negative c freundii
explain how the ferric citrate in bile esculin agar allows you to observe a positive result.
the bile inhibits its growth for other
explain how an exoenzyme works and an endoenzyme works in relationship to the cell
exoenzyme is a enzyme produced by cell that catalyze reactions outside of the cells endoenzyme is a enzyme that catlyze reaction inside the cell
a lactose fermenter is an organism that splits the ___ lactose into ___ and____ then ferments the ________.
phenol red broth contains a fermentable _____ included in the base medium are ____ and the ph indicator _____
phenol red broth is ____below pH 6.8 and ____above 7.4
as prepared the phenol red is at pH ____and appears red.
_________of peptone amino acids produces ____which raises the pH and turns the broth_____
an inverted durham tube small test tube is placed inside the the test tube to:
if the medium is inoculated, incubated and then observed to produce a pink results this indicates an alkaline condition caused by deamination. So reading carbohydrate fermentation test can be unreliable if reversion has occurred why?
understand /define completely reversion and apply to #7 and above
how many carbohydrates are added to each phenol broth and why
list the gram reaction and morphology of the enteric bacteria
Macconkey Agar is used to isolate and differentiate members of family enterobacteriacea based on their ability to ferment
know the terms selective medium and differential medium
what is the pH indicator used in MacConkey agar
the inclusion of bile salts and crystal violet makes Macconkey agar a _____ medium.
the pH indicator, neutral red is__ at a pH less than 6.8: and is ____at ph above 6.8
when bacteria are growing on MacConkey agar what will cause the Ph indicator to turn red
What do colonies of lactose nonfermenters look like on MacConkey agar what do fermenters (coliform) colonies look like
Which of bacteria used is/are coliforms
what will gram positive bacteria look like when plated on MacConkey agar
Any organism that grows well on macConkey agar regardless of appearance of growth is gram ______.