Micro lab finallll Flashcards
enzymes that are active all the time
constitutive enzymes
enzymes that are active only periodically (when their product is required)
Inducible or adaptive enzymes
enzyme that acts inside the cell
Endoenzyme
enzymes that are secreted from the cell and work in the cell’s environment and can reach substrates in agar
extracellular enzymes
Are enzymes consumed during a reaction?
NO
Enzyme: Catalase
substrate? products? types of organisms?
hydrogen peroxide
water and oxygen gas
All organisms that use oxygen for respiration
what does a catalase do?
breaks down hydrogen peroxide into water and molecular oxygen
Where are catalases located in mammals?
Mitochondrial intermembrane space
Do anaerobic bacteria make catalase? explain
No, they do not produce H2O2 as a byproduct so there is no need to have an enzyme to break it down. They use fermentative metabolism instead.
What process generally polymerizes individual subunits into macromolecules?
Dehydration synthesis
Catalase Positive?
Staphylococcus epidermidis
Catalase Negative?
Streptococcus mutans
Enzyme: Cytochrome c Oxidase
Substrate? Products? what type of organisms?
reduced form of cytochrome c
H2O or H2O2
All organisms that use oxygen for respiration
Cytochrome c Oxidase oxidizes and reduces what
oxidizes cytochrome c
reduces molecular oxygen
appearance of positive oxidase result?
negative?
Positive- purple
negative- no color change
Connection between cytochrome c oxidase and catalase?
both are made and used by aerobic respiration
cytochrome c oxidase can make H2O2 as a byproduct and catalase is used to detoxify the cell getting rid of the H2O2.
Oxidase postive?
Pseudomonas putida
Oxidase negative?
Escherichia coli
Cellulose: type of bonds, degraded by?
Held by beta (1,4) glycosidic bonds
degraded by cellulase
Major structural component of plants
cellulose
Starch: type of bonds, degraded by?
held by alpha (1,4) glycosidic bonds
degraded by amylase
reserve food supply for plants
amylase
commercial uses of amylase
detergents, makes glucose and syrup from starch
Enzyme: Cellulase
Substate? Product? type of organism?
cellulose
glucose monomers
cellulose decomposers in the soil and rotting wood (can be aerobic or anaerobic)
Enzyme: Amylase
Substrate? product? Type of organism?
starch
glucose monomers
cells that use subunits for energy or cell components
Appearance of Positive amylase result
Zone of hydrolysis after flooding with iodine
Positive for Amylase production?
Bacillus subtilis
Negative for amylase production?
Escherichia coli
Appearance of Cellulase growth
yellow color
chains of amino acids joined together by covalent peptide bonds
proteins
short chains of amino acids
peptides
Enzyme: Caseinase
Substrate? products?
Casein
Peptide chains/ amino acids
Type of agar used for caseinase production?
Milk agar
Appearance of positive for caseinase
Zone of hydrolysis
Positive for Caseinase production?
Bacillus subtilis
Negative for Caseinase production?
Escherichia coli
Enzyme: Gelatinas
Substrate? products?
gelatin
peptide/ amino acids
Can some human pathogens produce gelatinase?
YES
Appearance of positive for gelatinase production
Zone of hydrolysis
Positive for Gelatinase production?
Bacillus subtilis
Negative for Gelatinase production?
Escherichia coli
What do you flood the plate with for gelatinase production experiment?
dilute HCl
Why is gelatin not useful for isolating human pathogens?
Not useful for isolating human pathogens since it becomes liquefied during the 37°C incubation and because some microorganisms produce extracellular proteases that degrade gelatin
Heterotroph
gets carbon from the breakdown of an organic compound
Autotroph
gets carbon from air (CO2)
What is a source of carbon?
sugar
what is a process to make ATP?
Fermentation
Phototroph
gets energy from light source
Chemotroph
organism get energy from chemical source, organic source, or inorganic sources
Appearance of acid production
phenol red turns bright yellow
Appearance of gas production
bubble in the Durham tube
What happens to the pH surrounding an organism when fermentation occurs?
pH decreases
Positive result for fermentation
acid and/or gas production
Organisms (from the experiment) capable of fermentation (4)
Baciullus cereus
Escherichia coli
Citrobacter freundii
Staphylococcus epidermidis
What did Bacillus cereus not ferment?
lactose or sucrose (only glucose)
What did E. coli not ferment?
Sucrose (only glucose and lactose)
Why can’t hydrogen sulfide be detected in a durham tube?
it is extremely soluble in water. We will use the indicator ferric citrate.
Examples of Coliforms (3)
E. coli
Citrobacter freundii
Enterobacter aerogenes
How can you identify which plate is E. coli and which is Citrobacter freundii?
Do a cysteine desulfhydrase test
Appearance of positive cysteine desulfhydrase test
Black line along stab line
Positive for cysteine desulfhydrase?
Citrobacter freundii
Negative for cysteine desulfhydrase?
Escherichia coli
Which type of agar deep do you stab the inoculating needle into for a cysteine desulfhydrase test?
Peptone ion agar deep
Coliforms: \+/-? endospore/non-endospore forming? ferments lactose? Aerobic or anaerobic?
negative
non-endospore forming
ferments lactose within 24 hours at 37 degrees C
Aerobic or facultatively anaerobic
E. coli appearance on EMB plate
green metallic sheen
Enterobacter aerogenes appearance on EMB plate
fish eye colonies
Why is enterobacter aerogenes not an indicator organism?
because it can be found naturally in decaying vegetation
What enzyme is used in an indole test?
Enzyme tryptophanase breaks down amino acids tryptophan
What type of broth is used to test for Indole
1% tryptone broth
What is added to the inoculated Tryptone broth to follow up on an indole test?
Kovac’s reagent
Appearance of positive indole test? Negative?
Red layer that floats on the broth
colorless or pale orange band appears at the top
Methyl red is used to determine is an organism can ferment glucose by what process?
Mixed acid fermentation
Appearance of positive methyl red test? Negative?
red color = positive mixed acid fermentation (low/acidic pH)
Yellow color= negative mixed acid fermentation (neutral pH)
What does mixed acid fermentation mean?
many acids were produces and pH dropped
Vogues-Proskaur is used to determine is an organism can ferment glucose by what process?
butanediol fermentation
What do you add to the broth for a VP test?
alpha naphthol and 40% potassium hydroxide (KOH)
Appearance of positive VP test
Red color
For a citrate test, what is included in the media as a nitrogen source?
Ammonium phosphate
Appearance of citrate positive test? Negative
Green slant turns deep blue
Green slant remains green
Why does the slant in a citrate test turn blue?
it is caused by an increase in pH as organism grows and alkaline producers are formed
E. coli: +/- for:
Indole, Methyl Red, VP, Citrate
+, +, -, -
Enterobacter aerogenes: +/- for:
Indole, Methyl Red, VP, Citrate
-, -, +, +
energy efficient metabolism in the absence of free oxygen
anaerobic respiration
Organisms can use what as an external electron acceptor
sulfate, carbonate, or nitrate ions
Series of reactions that reduce nitrate to nitrogen gas
denitrification
What if the tube smells like ammonia?
Nitrate was able to reduce to ammonia
What if there is gas in the Durham tube? (nitrate reduction)
Nitrate was able to reduce to N2 or N2O
What if there is a red color after reagents were added? What are the reagents?
Nitrate was able to reduce to nitrite
alpha naphthylamine acetate and sulfanilic acid
What if there is a red color after adding a few flakes of zinc?
Nitrate was not able to reduce nitrate at all
Which organism could reduce nitrate to nitrite?
E. coli
Which organism could reduce nitrate to N2 or N2O?
Paracoccus denitrificans
Which organism did not reduce nitrate at all?
The control
List the steps of Nitrate Reduction in order.
Smell for ammonia
Check for gas bubbles
Add alpha napthylamine acetate and sulfanilic and check for red color
Add flakes zinc and check for red color
What are two ways to obtain nitrogen?
Nutrients in the environment
Gaseous nitrogen from the air
What is common to all types of nitrogen fixing bacteria? and what is it?
Nitrogenase enzyme complex
2 enzymes that convert gaseous nitrogen into ammonia and then into organic nitrogen
What are the two enzymes of nitrogenous enzyme complex?
Dinitrogenase
Dinitrogenase reductase
What uses a third protein that complexes with the nitrogenous enzyme complex to protect it from oxygen inactivation?
Azotobacter
Has nitrogen been added to the media in Nitrogen-fixing experiment?
NO
Why does the use of mannitol favor Azotobacter growth?
It can rapidly use mannitol as a carbon/energy source while many other organisms cannot.
Planting legumes every 4 years to replenish nitrogen in soil
Crop rotation
What is added to the nutrient medium for blood agar
5% sterile sheep blood
proteins that damage animal cell walls and can cause them to lyse
Hemolysins
Alpha hemolysis definition and appearance on blood agar
incomplete lysis of blood cells
greenish color/darkening around colonies due to methemoglobin
Beta hemolysis definition and appearance on blood agar
Complete lysis of red blood cell
complete clearing around colonies
Gamma hemolysis defintion and appearance on blood agar
no hemolysis
no change around colonies
cause tooth decay (alpha hemolysis)
Streptococcus mutans
cause strep throat (beta hemolysis)
Streptococcus pyrogenes
structures or substances produced by microorganisms that helps ability to form disease
Virulence factor
lyses blood cells
hemolysins
Dissolves fibrin clots in blood
Streptokinase
What does the candle jar incubation facilitates?
optimum growth and production of hemolysins
Appearance of Streptococcus mutans on blood agar
dull
Appearance of Staphylococcus epidermidis on blood agar
shiny
What is produced in homofermentation?
only lactic acid
What is produced in heterofermentation?
ethanol, lactic acid, and CO2
Do most lactic acid bacteria use peroxidases or catalase to degrade H2O2?
peroxidases
one species establishes themselves, followed by another species after growing conditions are rendered ideal
Succession
Media that is selective for Lactobacillus due to low pH
MRS media
Difference between catalase and peroxidase?
both are used to get rid of toxic hydrogen peroxide but only catalase will have oxygen as a product, peroxidase uses a completely different mechanism
recruits new cells to the biofilms and signal all members of the biofilm to form a certain compound simultaneously
Homeserine lactone
Adhesion of a few cells to a surface
Attachment
Growth, polysaccharide production, cell communication
Colonization
objects appear with significant contrast to their surroundings due to differences in refractive index of the specimen
Phase Contrast
Light passes though the specimen through the sides only
Dark field
A virion is composed of?
nucleic acid, capsid, envelope
viruses that infect bacteria
bacteriophages
number of plaque forming units per mL
Titer
responsible for a large percent of nosocomial infections
Staphylococci
Virulence factors of Staphylococcus aureus
B hemolysins and coagulase and exotoxin
causes plasma to clot
coagulase
surpasses the growth of unwanted organisms while encouraging the growth of specific microbes
selective media
Selective component of MSA (Mannitol Salt Agar)
7.5% NaCl
differential component of MSA
Mannitol and Phenol Red
colonies that ferment mannitol (2)
S. aureus and S. saprophyticus
do not ferment mannitol (2)
Staphylococcus epidermidis
appearance of positive mannitol fermentation
yellow
appearance of negative mannitol fermentation
pale or white on a pink medium
any intimate relationship or association of two dissimilar organism
Symbiosis
both populations benefit
mutualistic
one population benefits, one is unaffected
commensalistic
relationship benefits both populations but the association is not necessary for the survival of either species
Synergistic
host is harmed, while parasite benefits
parasitic
one population produces a substance, which inhibits the growth of another organism’s population
Antagonistic
cannot grow in the presence of oxygen, do not use oxygen as a final electron acceptor
obligate anaerobe
exclusively anaerobic type of metabolism but they are insensitive to the presence of O2
Aerotolerant
doing aerobic respiration in the presence of oxygen but also being able to do anaerobic respiration or fermentation when no oxygen is present
Facultative anaerobe
requires oxygen for respiration
Aerobic
prefer increased carbon dioxide and reduced oxygen tension
microaerophilic