Flashcards in Exercise 8:; Metabolism Deck (93):
what does catalase test for?
formation of hydrogen ions which are converted to toxic hydrogen peroxides;demonstrate the presence of catalase
what does a positive catalase result in?
a bubble formation after placing a drop of hydrogen peroxide on the colony on a glass slide
what does a negative catalase result in ?
no bubble formation after placing a drop of hydrogen peroxide on the colony on a glass slide
what reagant was added to catalase?
what does oxidase test for?
cytochrome oxidase; reduction of oxygen at the end of the ETC
what does a positive oxidase result in?
purple edging effect
what does a negative oxidase result in?
no edging effect
what reagent is used in oxidase?
what does carbohydrate fermentation test for?
breakdown by fermentation which results in acid production
what does a positive Carbohydrate Fermentation result in?
yellow color change from red with or without gas production
what does a negative Carbohydrate Fermentation result in?
no color change (stays red)
what does O+ and F+ mean in Carbohydrate Fermentation in both tubes?
positive for acid production ( both tubes turn yellow)
what does O - and F- mean in Carbohydrate Fermentation in both tubes?
negative for acid production (stays red in color)
what does Methyl Red test for?
used to identify bacteria that produce stable acid end products by means of mixed acid fermentation with glucose
what does a positive Methyl red result in?
red color change from yellow indicating mixed acid production
what does a negative methyl red result in?
no color change from yellow
what is added to the Methyl red tube after incubation?
a pH indicator called methyl red to indicate acid production
what does starch hydrolysis test for?
tests the ability of an organism to produce certain exoenzymes for example amylase
what does a positive starch hydrolysis result in?
a clear halo around the colonies after the addition of grams iodine.
what does a negative starch hydrolysis result in?
the entire medium is covered in dark blue/brown and also covered in grams iodine
what reagent is used in starch hydrolysis?
what does the nitrate reduction test test for?
used to determine the ability of an organism to reduce nitrate to nitrite
what does a positive nitrate reduction test result in?
yellow, pink or red color change
what does a negative nitrate reduction test result in?
no color change
what reagant is used in nitrate reduction test?
what does H2S production test for? (Iron Peptone Agar-IPA)
used to demonstrate the production of hydrogen sulfide.
what does a positive H2S(Iron Peptone Agar-IPA) production result in?
growth with black precipitate in the media
what does a negative H2S(Iron Peptone Agar-IPA) production result in ?
growth with no black precipitate
what does citrate utilization test for?
the ability of organisms to utilize citrate as a sole carbon source
what does a positive citrate result in?
green to blue color change (citrate was utilized as sole carbon source)
what does a negative citrate result in?
no color change ( citrate was not utilized)
what does motility test for?
used to test motility
what does a positive motility result in?
fanning out away from the stab line(tube looks cloudy)
what does a negative motility result in?
no fanning out from the stab line
what does urea hydrolysis test for?
what does a positive urea hydrolysis result in?
bright pink slant ( urea hydrolyzed, urease is present)
what does a negative urea hydrolysis result in?
light orange to yellow color ( urea not hydrolyzed, no urease present)
what does phenylalanine deamination test for?
detect the presence of phenylalanine deaminase.
what does a positive PD result in?
dark green color; avocado green color
what does a negative PD result in?
no color change
what is peptone in the test for carb fermentation?
to support the growth of the bacteria if the carbohydrate cannot be utilized
why is the carbohydrate needed in the CF test?
to test the bacteria
what is the Durham tube used for and what test?
the carbohydrate fermentation test; an inverted tube to collect gas that is formed.
what enzyme are you testing for in oxidase?
where is the cytochrome oxidase enzyme located?
end of the ETC
what enzyme is needed in order for a cell to exist in the presence of oxygen?
how can carbohydrates be broken down?
by fermentation which than results in acid production
what does the MR media contain?
peptone, glucose, a buffer
how long does MR need to be incubated for?
48 hours to allow for the fermentation to take place
what does the starch test do?
breaks down the polysaccharide down into usable glucose
what does the nitrate media contain?
peptone and beef extract to support growth as will as potassium nitrate
what happens when H2S is liberated by the enzyme?
the sulfur from the H2S combines with the iron in the PIA medium to form an iron sulfide
what is the iron sulfide manifested in?
a black precipitate in the medium
what medium is used for the citrate test?
simmons citrate agar
what enzyme is being used for citrate?
citrase or citrate-permease
what other things does the citrate test for?
tests for the presence of alkaline products as a result of citrate utilization
what indicator will be used in the citrate test?
bromothymol blue which will detect a ph change of greater than 7.5 from the conversion of ammonium dihydrogen phosphate to ammonia and ammonium hydroxide.
what does the citrate medium contain?
a carbon source( sodium citrate), a nitrogen source ( ammonium dihydrogen phosphate), and a pH indicator ( bromothymol blue
what makes the motility test motile?
what enzyme does the urea carry?
urease which breaks down urea to form two molecules of ammonia.
what broth is used for urea?
christensen's urea broth
what pH indicator is used in urea?
what does a positive urea test look like?
a magenta color( urea hydrolyzed, urease is present)
what does a negative urea test look like?
light orange, yellow
what enzyme does PD use?
what reagent is used in PD?
what does the PD test utilize?
the amino acid phenylalanine that is converted to phenylpyruvic acid.
what does BEA stand for?
Bile Esculin Agar
what is it selective for?
what is it differential for?
hydrolysis for esculin
what does a positive test in BEA look like?
growth of bacteria with a color change of media to black( bacteria all to hydrolyze esculin and survive in bile salts, Enterococcus spp.)
what does a negative BEA test look like?
growth of bacteria with no color change or no growth of bacteria.
when there is growth on a BEA plate what does that represent but no color change?
positive for bile salts negative for hydrolysis of esculin
what does MSA stand for?
Mannitol Salt agar
what is MSA selective for?
high salt concentration
what is MSA differential for?
what does a positive MSA look like?
growth of bacteria with a color change from red to yellow
what does a negative MSA look like?
growth of bacteria with no color change from red or no growth of bacteria
when there is growth on a MSA plate but no color change, what does that represent?
positive for high salt concentration but negative for fermenting mannitol
what does EMB stand for?
Eosin Methylene Blue
what is EMB selective for?
gram negative rods
what is EMB differential for?
what does a positive EMB look like?
a metallic green sheen color indicating positive for E.coli
what does a negative EMB look like?
growth of bacteria without color change or no growth of bacteria....stays its original color of dark red
what does MAC stand for?
what is MAC selective for?
what is MAC differential for?
what does a positive MAC look like?
growth of bacteria with a color change of the media to bright pink
what does a negative MAC look like?
growth of bacteria with no color change or no growth of bacteria
what can lead to false positives?
what do we use differential pH indicators for different tests?
different indicators is used to achieve several smooth color changes over a wide range of pH values
what is the advantage , with respect to disease, of having some of these enzymes?
allows bacteria to breakdown potentially harmful substances quickly