Quiz 5 Flashcards
20/20
There are two types of short term stock cultures what are they called?
Working stock culture
Reserve stock culture
Working stock culture contains what 2 possible ingredients?
typticase soy or nutrient agar slant
Fresh reserve culture should be prepared every ________
month
There are two types of long term stock culture storage what are they called?
Freeze drying (Lyphilization) and freezing
Why is a cryoprotectant like glycerol used in a storage medium that is freeze dryed?
To prevent formation of mini-ice crystals that can damage microbial cell membranes
Bacteria stored at -20C can be revived from cold storage for how long?
1-2 years (can be recultured and prepared for another round of freezing)
Non-Fastidious @ -70C maintain viability for how long?
5yrs
Fastidious @ -70c maintain viability for how long?
3yrs
is -20 or -70 preffered?
-70
Cell vibability is much higher on a what?
agar slant
What type of fridge will reduce viability
self defrosting feidge
WHat can’t strict anerobes do to reactive forms of oxygen created during metabolism
detoxify
What is the technique called for culturing anaerobes using a broth supplement with the reducing agent
thioglycollate broth
thioglycollate reacts with ____________ to make _________ incubate for how long?
oxygen, water, 48hrs
anerobic culture: pink or blue means what? and colourless means? What do you do for 1min if there is colour?
oxygen present, oxygen absent, boil.
How long to incubate gas pak anaerobic system?
24-48hrs 35c
Explain gas pak anaerobic system
chemical reaction to consume free oxygen gas in a sealed jar
gas pak anaerobic system - what is added to the chemicals in the envelope to activate reaction?
water
gas pak anaerobic system - if there is no moisture on the inside of the jar what do you do?
start again
gas pak anaerobic system - what two things are produced at the end of the reaction?
Hydrogen and CO2
gas pak anaerobic system - what colour does the indicator strip turn if pressence of oxygen
blue
Plants store glucose as very large molecules called _______
starch
Starch is made of _________
amylose
Amylose is a long branched ____________
polymer
When plants dies bacteria in the soil digest the ________ in the plants via an extracellular enzyme called __________
starch,amylase
What are the products of digestion of starch in plants?
Glucose and maltose
Glucose and maltose get transported across the __________ where they are used for _________
bacterial plasma membrane, energy and construction of other biomolecules
Starch is detected by adding ________
iodine
What will happen to starch if bacteria produce amylase?
Consumed after incubation
If no starch is detected? (Positive hydrolysis of starch) what would the colour be? and what if starch is present?
colourless, purple
starch hydrolysis - fat fuzzy snake means? | normal snake means?
positive, negative
If the iodine is yellow rather than brownish orange what does that mean?
Iodine is old - throw it out
Objective of the Citrate Utilization test.
To see if bacterium can use citrate as a sole source of carbon and energy
Membrane associated transporter for citrate utilization?
citrate permease
In the cytoplasim enzymes convert citrate to
pyruvate and CO2
If the bacteria use the citrate and CO2 combines with Na that makes what alkaline compound?
NaCO3
NH4+ is built by ________
enzymes
In an alkaline solution bromothymol blue turns
blue
Citrate utilization test - green to blue indicates? Green indicates?
positive test, negative
Citrate utilization test - what media is used at incubation details?
Simmons citrate agar slant. 35C 4 days
Indole (triptophan degrdation) test - to determine the ability of bacteria to split tryptophan (amino acid) into
indole and pyruvic acid
write out the equation of the indole test
tryotophan + 1/2 02 ——tryptophanase——pyruvate + NH3 + indole
indole test what reagent is used and incubation times?
kovacs, 24-48hrs - 35c
indole test - red layer means? no red layer means?
positive (presence of indole) negative (tryptophan not hydrolyzed)
Catalase test objective
detect catalase
catalase is an enzyme that
degrades H2O2
aerobic respiration H2O2 is made as _________
oxygen is reduced
H2O2 damages _____ and cell _______ and alters _______of some enzymes
DNA, membranes, active
O2 tolerant bacteria or require gas for metabolism use ________ to break down H2O2 into ________ and ______
catalase, water, O2
write out the reaction for catalase test
2H2O2 —-catalase—-2H2O + O2 (gas)
Catalase test - bubbles of O2 indicate what? weak or no bubbles indicates?
positive, negative
Oxidase test objective
to determine is bacteria have cytochrom oxidase
cytochrom oxidase is a participant in what?
electron transport during respiration
What uses energ in electrons that have been removed from food molecules making force across membrane?
electron transport molecules
cytochrom oxidase is at the end point of the
eletron transport chain
cytochrom oxidase collects electrons and O2 + H+ = H2O. What is used in the absense of O2
nitrate
oxidase test - cultures need to be no more than _____ hrs old
24
When cytochrom oxidase adds electrons to the oxidase reagent the reduced form turns
dark blue to purple in 10 secs
Objective of motility test
to see if bacterium is motile
flagella spin like
a corkscrew
Diffuse “cloud” bacteria growing from the stab indicates?
motile
bateria growing within stab?
non-motile
motility test - what kind of agar is used instead of 1.5%
0.4 % semi solid
motility test - Incubation times
24-48 hrs up to 7days
Objective of mannitol salt agar
isolate bacteria based on their salt tolerance and identify mannitol fermentation
Mannitol salt agar is ________ because only bacteria that tolerate ________ NaCl will grow
selective, 7.5%
Salt tolerant gram-positive cocci include
Staph, mirco, entero
acid from mannitol fermentation turns indicator _________
phenol red to yellow
yellow = mannitol fermentor
red = mannitol non-fermentor
The addition of sugar alchol make mannitol ________
differential
MacConkey agar objective
differentiate gram-negative enteric bacilli based on ability to grow on medium and ferment lactose
MacConkey plates often used ________contaminated specimens
fecal matter
MacConkey agar is _______ because gram-positive bacteria are inhibited by crystal violet and bile salt. gram negative bacteria are unaffected
selective
MacConkey agar - lactose is added to make it ________
differential
Lactose fermentor =
Non lactose fermentor =
pink to red, colourless
MacConkey agar - incubation times
24-48hr 35c
