Exam 2 Flashcards
what does the combination medium of MR and VP tests contain
peptone, glucose, and phosphate buffer
what is the MR test designed to detect
organisms capable of performing mixed acid fermentation
acids produced my those capable of performing mixed acid fermentation tend to be what
stable
what does MR stand for
Methyl Red
what is mixed acid fermentation verified by
the addition of methyl red indicator dye following incubation
when is methyl red the color red
at a pH of 4.4
when is methyl red the color yellow
at a pH of 6.2
when is methyl red the color orange
with a pH in between 4.4 and 6.2
what is a positive, negative, and inconclusive result of the MR test
positive: red
negative: yellow
negative/inconclusive: orange
what is the VP test designed for
organisms that are able to ferment glucose but quickly convert their acid products to acetoin and 2,3 butanediol
what is the broad process of VP test
acetoin-diacetyl + guanidine- red color
what is a positive and negative result of the VP test
positive: red
negative: no color change
what does VP test stand for
Voges-Proskauer test
what family of bacteria are SIM used for and what type of rod are they
Enterobacteriaceae
gram negative rods
what three activities are SIM medium used for
sulfur reduction, indole production from tryptophan, and motility
what are the two ways that sulfur can be reduced
with the enzyme cystein desulfurase and thiosulfate reductase
what do both enzymes of sulfur reduction produce
H2S gas
when either sulfur reaction occurs in SIM medium, what occurs
FeS forms(black precipitate)
what is a positive and negative result of sulfur reduction
positive: blackening of medium(sulfur reaction)
negative: no blackening(no sulfur reaction)
what is indole production possible by
the presence of tryptophan
what can tryptophan hydrolysis be detected by the addition of and what does it contain
Kovac’s reagent which contains DMABA
what is a positive and negative result of indole production
positive: red(presence of tryptophanase)
negative: no red color (doesn’t make tryptophase)
what is motility made possible by
the reduced agar concentration and the method incoulation
what is an indication of motility
growth that radiates in all direction and appears slightly fuzzy is an indication of motility
what does IMViC stand for
Indole, methyl red, voges-proskauer, and citrate
what is IMViC used for
to distinguish between members of the family Enterobacteriaceae
what is TSIA designed to differentiate between
glucose fermentation, lactose fermentation, sucrose fermentation, and sulfur reduction
what is TSIA composed of
3 carbohydrates, animal proteins, ferrus sulfate and sodium thiosulfate
what is the pH indicator of TSIA
phenol red
what is the hydrogen sulfide indicator
iron
what can show up as a false positive because changes back to basic after all glucose is used up
reversion
KIA is identical to TSIA in form and function except what
KIA does not include sucrose
yellow slant, yellow butt KIA
glucose and lactose fermentation with acid accumulation in slant and butt
yellow slant, yellow butt TSIA
glucose and lactose and or sucrose fermentation with acid accumulation in slant and butt
red slant and yellow butt (TSIA)
glucose fermentation with acid production, proteins catabolized aerobically with alkaline products
red slant and red butt (TSIA)
no fermentation, peptone catabolized aerobically and anaerobically with alkaline products, not from enterobacteriaceae
red slant, no change in butt (TSIA)
no fermentation, peptone catabolized aerobically with alkaline products, not from enterobacteriaceae
no change in slant and no change in butt (TSIA)
organism is growing slowly or not at all, not from enterobacteriaceae
black precipitate in agar (TSIA)
sulfur reduction(acid condition), from fermentation of glucose or lactose, exists in the butt even if the yellow color is obscured by the black precipitate
crack in a lifting of agar (TSIA)
gas production
what does the citrate utilization test tell us about
organism’s ability to use citrate as their sole carbon source and perform citrate fermentation
what is a defined medium and give an example of it
amount and source a of all ingredients are carfeully controlled and simmons citrate agar is an example
bacteria that does not possess citrate permase will not grow on what medium
ammonium as the sole nitrogen source
this is the enzyme citrate pos bacteria use to hydrolyze citrate into oxalocetate and acetate(oxalocetate is then converted to pyruvate)
citrate lyase
what is a positive result of the citrate utilization test
blue and no color change but GROWTH (citrate is utilized)
what is a negative result of the citrate utilization test
no color change and no growth (citrate is not utilized)
metabolic process by which an organic molecule acts as an electron donor and one ore more of its organic products as the FEA
carbohydrate fermentation
what is carbohydrate fermentation used to include
hydrolysis of disoccharrides prior to fermentation
organism that splits the disaccharide lactose and ferments the monosccharides
lactose fermenter
phenol red broth and MR and VP broth
differential fermentation media
this is a differential test medium prepared as a base to which a carbohydrate is added
phenol red broth
what does phenol red broth include
peptone and phenol red
what it the pH indicator of phenol red broth
phenol red
when is phenol red the color yellow
below pH of 6.8
when is phenol red the color pink
above pH of 7.4
when is phenol red the color red
in between pH of 6.8 and 7.4
this is added to each tube as an indicator of gas production
from fermentation, indicated by a buubble
inverted Durham tube
yellow broth and bubble in tube
fermentation with acid and gas end products
yellow broth and no bubble in tube
fermentation with acid end products, no gas produced
red broth and no bubble in tube
no fermentation
pink broth and no bubble in tube
degradation of peptone and alkaline end products
