Microbiology Lab Final

Front 1

What is the reagent that serves as the substrate in the catalase test?

Back 1

H2O2; hydrogen peroxide

Front 2

What type of metabolism is associated with catalase production?

Back 2

aerobic metabolism

Front 3

For what product is one testing when using the catalase test?

Back 3

oxygen in the form of bubbles

Front 4

If your catalase test was POSITIVE, to what 2 possible genera could the microorganism belong?

Back 4

Staphylococcus and Micrococcus

Front 5

What genera of bacteria is the catalase test used to distinguish between?

Back 5

Gram-positive cocci

catalase POSITIVE: Staphylo and Micro
catalse negative: Strepto, Lacto, and Entero

Front 6

Equation catalyzed by catalase

Back 6

2 H2O2 -> 2H2O + O2

Front 7

Enzymes that are essential to the cell and are produced at all times

Back 7

Constitutive enzymes

Front 8

Enzymes produced only if the appropriate substrate is available

Back 8

Inducible or adaptive enzymes

Front 9

Enzymes that act outside of the cell in which they are produced

Back 9

Exoenzymes

Front 10

Enzymes that act inside the cell

Back 10

Endoenzymes

Front 11

Enzymes

Back 11

proteins that serve as biological catalysts and are NOT consumed in the reaction

Front 12

What is the function of cytochrome oxidase?

Back 12

The enzyme catalyzes the oxidation of cytochrome and reduction of O2.

Required to generate the H+ gradient used to produce ATP through the ETC

Front 13

Oxidase test used to differentiate among which groups of bacteria?

Back 13

Pseudomonads (positive) - Pseudomonas putida

Enterobacteria (negative) - Escherichia coli

Front 14

Amylase breaks down _____.

Back 14

Starch; alpha-1,4- glycosidic bonds between glucose molecules

Front 15

Cellulase breaks down _____.

Back 15

Cellulose; beta-1,4- glycosidic bonds between glucose molecules

Front 16

Which organism studied was amylase positive? amylase negative?

Back 16

POSITIVE: Bacillus subtilis

negative: Escherichia coli

Front 17

Which organism studied was cellulase positive?

Back 17

Cytophaga hutchinsonii

Front 18

Proteases

Back 18

enzymes that hydrolyze proteins into peptides so they can be transported into the cell

Front 19

Peptide

Back 19

short chain of amino acids

Front 20

Protein

Back 20

amino acids joined by peptide bonds

Front 21

Which organism studied produces caseinase?

How do you know?

Back 21

Bacillus subtilis

clear under colony on milk agar plate

Front 22

Which organism studied produces gelatinase?

How do you know?

Back 22

Bacillus subtilis

clear under colony on gelatin agar plate after flooded with HCl

Front 23

Catabolism can utilize which two (2) pathways?

Back 23

(1) Respiration (if terminal e- present)
(2) Fermentation

* Glycolysis common to both

Front 24

Possible Fermentation Products

Back 24

(1) CO2
(2) acids
(3) alcohol

Front 25

What indicator is used in determining carbohydrate fermentation?

Back 25

Phenol red

(yellow under acidic conditions)

Front 26

Fermentation Products detected with Saccharomyces cerevisiae

Back 26

CO2 and ethyl alcohol

Front 27

Fermentation Products detected with Lactococcus lactis

Back 27

lactic acid

* causes casein protein in milk to coagulate

Front 28

Carbohydrate Broth Results for

Citrobacter freundii

Back 28

G, L, S (AG)

Front 29

Carbohydrate Broth Results for

Staphylococcus epidermidis

Back 29

G, L, S (A)

Front 30

Carbohydrate Broth Results for

Escherichia coli

Back 30

G, L (AG)

Front 31

Carbohydrate Broth Results for

Bacillus cereus

Back 31

G (A)

Front 32

Cysteine desulfhydrase

Back 32

cleaves sulfydryl group (‐SH) from cysteine releasing hydrogen sulfide gas (H2S)

2 of 20 amino acids contain sulfur ‐Cysteine & Methionine

Front 33

Which organism studied produces cysteine desulfhydrase?

Back 33

Citrobacter freundii

Front 34

Peptone Iron Agar

Back 34

used to test for cysteine desulfhydrase

peptone is rich in cysteine
ferric citrate + H2S = FeS (ferrous sulfide)

Front 35

IMViC series

Back 35

tests to distinguish coliforms (E. coli and E. aerogenes)

Indole
Methyl Red
Voges-Proskauer
Citrate

Front 36

Indole Test

Back 36

part of IMViC for coliforms (E. coli POSITIVE)

tryptonphan (tryptophanase) -> indole, pyruvic acid, ammonia
+ Kovac's reagent = RED top layer

Front 37

Methyl Red Test

Back 37

part of IMViC for coliforms (E. coli POSITIVE)

Mixed acid fermentation = RED

Front 38

Voges-Proskauer Test

Back 38

part of IMViC for coliforms (E. aerogenes POSITIVE)

Butanediol fermentation (acetoin) = pink/orange/red

Front 39

Simmons Citrate Test

Back 39

part of IMViC for coliforms (E. aerogenes POSITIVE)

> Sodium citrate is only C source
> Ammonium phosphate as only N source
> Bromthymol blue is pH indicator

Citrate permease = produce alkaline products = BLUE

Front 40

Bromthymol blue

Back 40

pH indicator in Simmons Citrate Test of IMViC

Front 41

Denitrification

Back 41

reactions that reduce nitrate to nitrogen gas

In anaerobic respiration some use nitrate as external electron acceptor

> Paracoccus denitrificans

Front 42

What is the organism studied that produces nitrate reductase AND nitrite reductase?

Back 42

Paracoccus denitrificans

Front 43

What is the organisms studied that produces nitrate reductase?

Back 43

Escherichia coli

Front 44

Nitrogen fixation

Back 44

ability of an organism to obtain N2 from the air and convert it to ammonia and organic nitrogen

Symbiotic relationship with plants OR free‐living (non‐symbiotic)

Front 45

Enzyme Complex used by organisms that fix nitrogen

Enzyme inhibited by oxygen

Back 45

nitrogenase enzyme complex

Dinitrogenase reductase

Front 46

Which organism studied is free-living and nitrogen-fixing?

What qualities does it have to accomplish this?

Back 46

Azotobacter vinelandii

> Protein bound to the nitrogenase complex to protect the dinitrogenase reductase from O2
> Alginate capsule that slows the rate of oxygen absorption

Front 47

Hemolysin

Back 47

a substance produced by a bacteria that damages/destroys red blood cells; virulence factor

Front 48

Alpha Hemolysis

Back 48

leakage of ions from red blood cells caused by alpha‐hemolysin proteins

Ex. Streptococcus mutans

Front 49

Beta Hemolysis

Back 49

complete rupture of red blood cells caused by beta‐hemolysin proteins

Ex. Streptococcus pyogenes

Front 50

Gamma Hemolysis

Back 50

no effect on red blood cells; no hemolysins

Front 51

Method of Isolation and Identification of Streptococci

Back 51

Blood agar to determine hemolysin production

Used candle jar because Streptococci found in human body prefer increased CO2 (microaerophilic)

Front 52

Virulence Factor

Back 52

structures or substances produced by a microorganism which enhances its ability to cause disease

Ex. capsules, coagulase, hemolysin, endospores

Front 53

Aerotolerant anaerobes

Back 53

can grow in presence of oxygen but do not use the oxygen for respiration; obtain energy from fermentation

Front 54

Homofermentative

Back 54

Only product is lactic acid

Front 55

Heterofermentative

Back 55

Products are ethanol, CO2 and lactic acid

Front 56

Lactic Acid Bacteria

Back 56

> Ferment sugar to produce lactic acid
> aerotolerant anaerobes
> most catalase negative

Ex. Streptococcus, Lactococcus, Lactobacillus

Front 57

Production of Yogurt from Milk

Back 57

fermentation

Starter culture of Streptococcus produces acid, at pH of 6 Lactobacillus grows, at pH of 5 Streptococcus ceases to grow

Front 58

MRS medium

Back 58

used to enrich for Lactobacillus

selective due to low pH

Front 59

Lactobacillus Isolation Steps

Back 59

(1) Enrichment - MRS broth
(2) Isolation - MRS plate
(3) Characterization - Gram stain and catalase test

Front 60

Formation of Biofilms (3 steps)

Back 60

(1) Attachment
(2) Colonization: polysaccharide production, cell communication
(3) Development

Front 61

Quorum Sensing

Back 61

communication of cells in biofilms

homoserine lactone: biofilm cells produce; it builds up to certain level, causes response from neighboring cells (ex. release of an enzyme, recruitment to the biofilm)

Front 62

Virus

Back 62

• Obligate intracellular parasite
• Contain DNA or RNA within the capsid (protein)
• Host specific

Front 63

Stages in a Viral Infection

Back 63

(1) Attachment
(2) Injection
(3) Viral Synthesis
(4) Viral Assembly
(5) Release of Virions

Front 64

Plaque

Back 64

clearing within lawn of bacteria caused by cell lysis due to viral infection

Front 65

Darkfield and Phase Contrast Microscopy

Back 65

Types of light microscopy

> allow you to see motile, living cells with sufficient contrast without staining

Wet Mount– view living cells, no staining, no procedure other than putting coverslip on slide

Front 66

Selective Medium

Back 66

selects for a bacteria and does not allow other to grow

Front 67

Differential Medium

Back 67

allows differentiation between different bacteria

Front 68

Which organism studied ferments mannitol and produces coagulase?

Back 68

Staphylococcus aureus

Front 69

What were the two Staphylococci studied and how were they identified?

Back 69

Staphylococcus aureus = yellow on MSA (mannitol salt agar + phenol red)

Staphylococcus epidermidis = pink

Front 70

Coagulase

Back 70

enzyme which converts fibrinogen to fibrin causing plasma to clot; virulence factor

Front 71

manifestations of hypothyroidism - myxedema

Back 71

puffy face, enlarged tongue, hoarse/husky voice, pleural effusion

Front 72

Symbiosis

Back 72

intimate relationship between 2 dissimilar organisms

Front 73

What two organisms were involved in a commensalistic relationship?

Back 73

Clostridium sporogenes (obligate anaerobe)
+
Staphylococcus epidermidis (facultative anaerobe)

Front 74

Mutualism

Back 74

both benefit, necessary for survival

Ex. Legumes and Rhizobium

Front 75

Commensalism

Back 75

one benefits, other unaffected

Ex. C. sporogenes and S.epidermidis

Front 76

Synergism

Back 76

both benefit, not necessary for survival

Front 77

Parasitism

Back 77

one benefit, other hurt

Front 78

Antagonism

Back 78

one inhibits growth of another

Front 79

Leghemoglobin

Back 79

iron-containing heme binds O2 in nodule

> gives nodules pink color

Front 80

Root Nodulation

Back 80

(1) bacteria attaches to root hair (polysaccharide on bacteria w/ lectin on hair)
(2) infection thread
(3) stimulate root cell rapid division