Lab Final Flashcards
the sum of the reactions that are associated with the life of a cell
metabolism
biological catalysts that allow spontaneous unfavorable reactions to occur; convert substrates to products
enzyme
degrade large molecules outside of the cell into units that are small enough to be transported across the cell membrane
exoenzymes
degrade large molecules to simpler molecules releasing energy or synthesizing molecules that are needed by the cell
endoenzymes
enzymes that are produced only if its substrate is available, in an effort to conserve the cell’s energy
inducible or adaptive enzymes
enzymes that are essential to the cell, so they are produced at all times
constitutive enzymes
Hydrogen peroxide is a byproduct of what kind of metabolism?
aerobic
What are the substrates, products, and reagent/indicator for a catalase test?
Substrate: hydrogen peroxide
Products: water and O2
Reagent/Indicator: hydrogen peroxide
What organism was tested to be catalase positive? Catalase negative?
Positive: Staphylococcus epidermis
Negative: Streptococcus mutans
What type of bacteria is usually catalase Positive? Negative?
Positive: aerobic bacteria
Negative: fermentative or anaerobic bacteria
test used to differentiate medically relevant genera by seeing if cytochrome oxidase is produced by microbes
oxidase tests
What are the substrates, products, reagent/indicator, and media for an oxidase test? What does a positive result look like?
Substrate: O2 Product: water Reagent/Indicator: oxidase reagent Media: TSA plate Positive Result: immediately turns microbe blue/purple
What organism was tested to be oxidase positive? Oxidase negative?
Positive: Pseudomonas putida
Negative: E. coli
What kind of cells make oxidase enzymes?
cells that do respiration
transfers electrons to O2 to from water or hydrogen peroxide as the final electron transfer in electron transport of aerobic respiration
cytochrome oxidase
(CH2O)_n
carbohydrates
single molecule of a sugar (ex. glucose)
monosaccharide
polymers of glucose (ex. cellulose, starch)
polysaccharide
enzyme that hydrolyzes start into glucose to be transported into a cell for metabolism
amylase
commercial and industrial uses of microbially produced amylases
food, fermentation, brewing, distilling, textiles, paper, etc
What links cellulose?
Beta-1,4
What links starch and glycogen?
Alpha-1,4
What are the substrates, products, reagent/indicator, and media for an amylase test? What does a positive result look like?
Substrate: Polysaccharide (starch) Products: Oligosaccharides of glucose Reagent/Indicator: iodine Media: starch agar plate Positive Result: zone of hydrolysis
What organism tested positive for the amylase test? Negative?
Positive: Bacillus subtilis
Negative: E. coli
enzyme that hydrolyzes cellulose into glucose to be transported into the cell for metabolism
cellulase
Where is cellulose found?
eukaryotic (plant and algae) cell walls
What are the substrates, products, reagent/indicator, and media for a cellulose test? What does a positive result look like?
Substrate: polysaccharide (cellulose)
Product: oligosaccharides of glucose
Reagent/Indicator: none
Media Used: Dubos broth and agar with paper
Positive Result: plate turns yellow; broth shows paper degradation
Why was Cytophaga hutchinsonii used in the cellulase test?
aerobic degradation of cellulose in paper samples
amino acids joined by peptide bonds
protein
short chain of amino acids
peptide
enzymes that degrade proteins
proteases
commercial uses of proteases
laundry detergent, stain remover, meat tenderizer
milk protein
casein
how do you test for caseinase?
milk agar (nutrient agar + skim milk)
protein from bones of animals
gelatin
how do you test for gelatinase?
gelatine agar (nutrient agar + gelatin)
What are the substrates, products, reagent/indicator, and media for a caseinase test? What does a positive result look like?
Substrate: Milk Product: Pepties Reagent/Indicator: none Media: Milk Agar Positive result: Zone of Hydrolysis
What organisms tested positive in the caseinase test? Negative?
Positive: Bacillus subtilis
Negative: E. coli
What are the substrates, products, reagent/indicator, and media for a gelatinase test? What does a positive result look like?
Substrate: Gelatin Product: Peptides Reagent/Indicator: HCl Media: Gelatin Agar Positive result: Zone of Hydrolysis
What organisms tested positive in the gelatinase test? Negative?
Negative: E. coli
Positive: Bacillus subtilis
Can catabolism occur by fermentation or respiration?
both
common to fermentation & respiration; conversion of glucose to pyruvate
glycolysis
What decides if respiration will occur vs. fermentation
if a terminal electron acceptor is present, respiration will occur
Fermentation products (general)? Fermentation products in lactobacillus and saccharomyces?
General: CO2, acids, alcohol, etc.
Lactobacillus: lactic acid
Saccharomyces: alcohol and O2
How do you test if an organic is able to ferment a carbohydrate?
Use nutrient broth with 1 fermentable carbohydrate and a pH indicator. Inoculate organism and if it can ferment carbohydrate it will produce acid from fermentation (drops pH and turns broth yellow)
How does phenol red work?
Red at pH 7
Yellow below pH 6.9
What will be the result if an organism can ferment carbohydrates?
It will produce acid which drops the pH turning the broth yellow
2 amino acids that contain sulfur
cysteine & methionine
What happens when cysteine desulffhydrase cleaves sulfydryl group from cysteine?
releases hydrogen sulfide gas
What are the substrates, products, reagent/indicator, and media for a cysteine desulfhydrase test? What does a positive result look like?
Substrates: Cysteine Product: Pyruvate, NH3 (ammonia), H2S (hydrogen sulfide) Reagent/Indicator: Ferric citrate Media: Peptone iron agar deep Positive Result: black precipitate
What organism tested positive in the cysteine desulfhydrase test? Negative?
Positive: Citrobacter freundii
Negative: E. coli
What happens if an organism makes cysteine desulfhydrase?
H2S will react with ferric citrate to make ferrous sulfide (FeS) which is black
4 biochemical tests used to more precisely identify coliform; used to check quality of water, milk, other foods
IMViC series
What does IMViC stand for?
Indole Methyl Red Voges-Proskauer and Citrate test
useful in differentiation between several gram negative, enteric bacteria
IMViC
determines if organism produce tryptophanase
indole
determines if organisms ca ferment glucose by mixed acid fermentation
methyl red
determines if organisms can ferment glucose by butanediol fermentation
Vogues-Proskauer
determines if organisms can use citrate as a sole carbon source
Citrate
What are the substrates, products, reagent/indicator, and media for an indole/tryptophanase test? What does a positive result look like?
Substrates: Tryptophan Products: Indole Reagent/Indicator: Kovac's reagent Media: 1% tryptone broth Positive Result: Red/pink layer on top
What organism tested positive for an indole test?
Positive: E. coli
Negative: Ent. aerogenes
Some organisms use mixed acid fermentation to ferment glucose and produce lots of acid. What is the pH indicator?
Methyl Red
What does the MRVP broth contain?
glucose
What does the Voges-Proskauer test look for?
Organisms that use butanediol fermentation and produce neutral products such as acetoin from the fermentation of glucose
What are the substrates, products, reagent/indicator, and media for a citrate/citrate-permease test? What does a positive result look like?
Substrate: Citrate Product: Alkaline products Reagent/Indicator: Bromthymol blue Media: Simmon's citrate agar Positive: Slant becomes blue
What organism tested as positive in the MR test? Negative?
Positive: E. coli
Negative: Ent. aerogenes
What organism tested as positive in the VP test? Negative?
Positive: Ent. aerogenes
Negative: E. coli
What organism tested as positive in the citrate test? Negative?
Positive: Ent. aerogenes
Negative: E. coli
What does E. coli reduce to in a nitrate test?
NO2-
What does P. denitrificans reduce to in a nitrate test?
N2 or N2O
What are the substrates, products, reagent/indicator, and media for a nitrate reductase test? What does a positive result look like?
Substrate: Nitrate Product: Nitrite Reagent/Indicator: alpha-naphthylamine acetate & sulfanilic acid Media: Nitrate broth with Durham tube Positive: Red color
What are the substrates, products, reagent/indicator, and media for a nitrite reductase test? What does a positive result look like?
Substrate: Nitrite Product: N2O or N2 gas Reagent/Indicator: Durham tube Media: Nitrate broth with Durham tube Positive: bubbles in durham tube
Purpose of nitrogen fixation lab
to isolate a nitrogen-fixing microbes using an enrichment culture technique
What is nitrogen needed for?
nucleic acids, proteins, and some phospholipids
Sources of Nitrogen
N2 - air NH3 - ammonia NO3 - nitrate NO2 - nitrite amino acids - organic nitrogen
the ability of an organism to obtain N2 from the air and covert it to ammonia and organic nitrogen
nitrogen fixation
What do organisms use to fix nitrogen?
nitrogenase enzyme complex
Dinitrogenase reductase is ____ by oxygen
inhibited
aerobic, free-living, nitrogen fixing soil bacterium
azotobacter vinelandii
Why does Azotobacter vinelandii use a protein to bind to the nitrogenase complex?
To protect the dinitrogenase reductase from oxygen
produces alginate capsule that slows the rate of oxygen absorption
Azotobacter vinelandii
breaks down tryptophan into indole, pyretic acid and ammonia
tryptophanase
Methyl red turns red below pH
4.2
carbon source in a citrate test
sodium citrate
nitrogen source in citrate test
ammonium phosphate
pH indicator in citrate test
bromythmol blue (green at pH 7, blue above)
transports citrate from agar inside the cell to be used as carbon source
citrate permease
if an organism can use citrate as a carbon source an ammonium phosphate as a nitrogen source, what will happen to the citrate slant?
organism will grow and produce alkaline product that will turn the slant from green to blue
breaks down tryptophan into indole, pyruvic acid and ammonia
tryptophanase
beta hemolysis on blood agar
clear colonies, Streptococcus pyogenes
alpha hemolysis on blood agar
green colonies
structures or substances produced by a microbe which enhance its ability to cause disease
virulence factor
What are the substrates, products, reagent/indicator, and media for a coagulase test? What does a positive result look like?
Substrate: fibrinogen Product: fibrin Reagent/Indicator: Solidification/clots Media: Plasma Positive: white solid
What organism tested positive for coagulase on a MSA plate? Negative?
Positive: Staphylococcus aureus (yellow pigmented)
Negative: Staph epidermis
genera that is gram +, catalase +, and salt tolerant
staphylococcus
enzyme which converts fibrinogen to fibrin causing plasma to clot; virulence factor
coagulase
What is on a Mannitol Salt Agar plate?
7.5% salt
Mannitol - selective for mannitol fermenters
Phenol red - pH indicator
How would an organism test positive for coagulase in a plasma tube?
the plasma will clot
intimate relationship between 2 dissimilar organisms
symbiosis
both organisms benefit fro the relationship (ex. lichens)
mutualism
one organism benefits, the other is unaffected (ex. Bacteroides & E. coli)
commensalism
both organisms benefit but relationship is not necessary for their survival; each supplies a nutrient required for the other under certain conditions (Ex. lactobacillus & enterococcus can grow without each other on enriched media but can only grow on minimal media if both are present)
synergism
host is harmed but parasite benefits (ex. fleas, Bdellovibrio & E. coli)
parasitism
one organism produces substance that inhibits another organism (ex. penicillium)
antagonism
gram positive, streptobacillus, catalase negative
lactobacillus acidophilus
symbiotic relationship with legumes
Rhizobium
a protein on the surface of the root hair
lectin
a structure formed when Rhizobium bacteria enters the root hair and moves through the root cells
Infection thread
an iron containing heme similar to hemoglobin found in plants
leghemoglobin
gives the nodule its red or pink color
leghemoglobin
restoring soil fertility by providing nitrogen source for the plants; a leguminous crop is substituted for the main cash crop in a field after a certain number of growing season
crop rotation
lytic cycle
- phage attaches to host cell and injects DNA
- phage DNA circularizes and enters lytic cycle or lysogenic cycle
- new phage DNA and proteins are synthesized
- cell lyses, releasing phage virions
lysogenic cycle
- phage attaches to host cell and injects NA
- phage DNA circularizes and enters lytic cycle or lysogenic cycle
- phage DNA integrates within the bacterial chromosome by recombination, becoming a prophage
- Lysogenic bacterium reproduces naturally
- Occasionally, the prophage may excise from the bacterial chromosome by another recombination event, initiating a lytic cycle
chemical that kills or inhibits the growth of mirobes
antimicrobial agent
agent that is lethal to microbes
cidal agent
agent that inhibits growth and does not kill microbes
static agent
antimicrobial agent used only on inanimate objects (ex. ammonia, bleach, ethanol)
disinfectant
antimicrobial agent that can be applied to living tissue (ex. iodine, ethanol)
antiseptic
Factors affecting the effectiveness of a chemical agent
contact time and concentration of agent
effectiveness of an antimicrobial agent is determined by the size of the
zone of inhibition
clear area around the anti microbic disc where there is no bacterial growth
zone of inhibition
size of the zone of inhibition depends on
- diffusion rate of the chemical agent into the media
- concentration of the bacteria
- type of growth medium
chemical substance produced by a microbe that kills or inhibit the growth of other microbes (ex. penicillin)
antibiotic
way through which antibodies kill or prevent the growth of pathogens
mode of action
What is penicillin’s mode of action?
penicillin prevents proper synthesis of the cell wall, subjecting it to lysis
smallest amount of agent needed to inhibit the growth of a microbe
Minimum Inhibitory Concentration
standard procedure used to measure antimicrobial activity
Kirby Bauer method
30S bacterial ribosome inhibitor
Gentamicin or Tetracycline
inhibits 50S ribosomal subunit
Chloramphenicol
50S bacterial ribosome inhibitor
Erythromycin
inhibits transpeptidase, cannot synthesis cell walls
ampicillin
interferes with cell wall synthesis
cefoxitin