Practical Lab Final Images

Question 1

1) What media is this? What colors can it be?
2) What bacteria is this and what color is it supposed to look like?

Answer 1

1) EMB; media color ranges from yellow to red
2) E. aerogenes; larger colonies, pinkish to brown center

Question 2

1) What media is this?
2) What bacteria is this? What color is it supposed to be?

Answer 2

1) EMB
2) E. coli; dark centered colonies with clear edges and tends to have a metallic sheen

Question 3

1) What media is this?
2) What bacteria is this? What has it done to the media and why?

Answer 3

1) BA (blood agar)
2) Alpha strep; dark brown due to alpha hemolysis

Question 4

1) What media is this?
2) What bacteria is this? What has it done to the media and why?

Answer 4

1) BA
2) SA; clearing has occurred and media has brightened due to beta hemolysis

Question 5

1) What media is this?
2) What bacteria is this? What has it done to the media and why?

Answer 5

1) BA
2) S. epi; nothing has occurred in the media due to gamma hemolysis

Question 6

1) What media is this?
2) What bacteria is this? What has it done to the media?

Answer 6

1) MSA
2) S. epi; media remains pink because no fermentation occurred

Question 7

1) What media is this?
2) What bacteria is this? What has it done to the media and why?

Answer 7

1) MSA
2) S. aureus; the phenol red turned yellow due to fermentation (and decreased pH)

Question 8

1) What media is this?
2) What bacteria is this? What has it done to the media and why?

Answer 8

1) MAC
2) E.coli; it turned the neutral red indicator red since acids were produced by lactose fermentation. Growth was inhibited by bile salts.

Question 9

1) What media is this?
2) What bacteria is this? What has it done to the media and why?

Answer 9

1) MAC
2) S. ent (Salmonella enteritidis); the bacteria grew well, but the media remained yellow because no fermentation occurred.

Question 10

1) What media is this?
2) What bacteria is this? What has it done to the media and why?

Answer 10

1) MAC
2) S. son (Shigella sonnei); the bacteria grew well, but the media remained yellow because no fermentation occurred.

Question 11

1) What media is this?
2) What bacteria is this? What has it done to the media and why?

Answer 11

1) Salmonella-Shigella Agar (SS)
2) E. coli; growth was limited by bile salts but turned the agar red due to lactose fermentation decreasing the pH (neutral red indicator).

Question 12

1) What media is this?
2) What bacteria is this? What has it done with the media?

Answer 12

1) SS
2) S. enteritidis; transparent colonies with dark centers due to H2S formation

Question 13

1) What media is this?
2) What bacteria is this? What has it done to the media?

Answer 13

1) SS
2) Shigella sonnei; has reddish pink colonies but has not changed the media

Question 14

1) What test is this?
2) What did the bacteria do in the media?
3) What bacteria give this result?

Answer 14

1) TSI
2) A/A: Anaerobic fermentation of sucrose/lactose and produced gas; no H2S formation.
3) E. coli, K. pneumoniae, E. aerogenes

Question 15

1) What test is this?
2) What did the bacteria do in the media?
3) What bacteria give this result?

Answer 15

1) TSI
2) K/A: Aerobic (glucose) and anaerobic (sucrose/lactose) fermentation and gas formation; no H2S formation
3) E. aerogenes

Question 16

1) What test is this?
2) What did the bacteria do in the media?
3) What bacteria give this result?

Answer 16

1) TSI
2) A/A: Anaerobic fermentation of sucrose/lactose and produced gas; H2S formation occurred.
3) Citrobacter freundii (CF), Proteus vulgaris (PV)

Question 17

1) What test is this?
2) What did the bacteria do in the media?
3) What bacteria give this result?

Answer 17

1) TSI
2) K/K aerobic respiration (glucose) only; no H2S or gas formation
3) B. subtilis; CX

Question 18

1) What test is this?
2) What did the bacteria do in the red tube?
3) What did the bacteria do in the yellow tubes?

Answer 18

1) Phenol red sugars (glu, lac, man, suc, xyl)
2) Nothing; stayed red and no gas formed
3) Ferment the sugar and produce acid, turning phenol red yellow.

Question 19

1) What test is this?
2) What did the bacteria do in the red tube?
3) What did the bacteria do in the yellow tubes?

Answer 19

1) Phenol red sugars
2) Nothing; stayed red and no gas was produced
3) Ferment the sugar and produce acid and gas, turning phenol red yellow and adding gas to the Durham tubes.

Question 20

1) What test is this?
2) What did bacteria do in the top tube? What bacteria do(es) this?
3) What did bacteria do in the middle tube? What bacteria do(es) this?
4) What did bacteria do in the bottom tube? What bacteria do(es) this?

Answer 20

1) Litmus milk (LM)
2) Top: Lactose fermentation occurred (white); no clearing and clotting. B. cereus.
3) Middle: No fermentation occurred, but clearing and clotting occurred. B. subtilis.
4) Bottom: No fermentation, clearing, or clotting occurred. S. sonnei, E. faecalis, Cx.

Question 21

1) What test is this?
2) What did bacteria do in the top and bottom tubes? What bacteria do(es) this?
3) What did bacteria do in the middle tube? What bacteria do(es) this?

Answer 21

1) Litmus milk (LM)
2) Top and bottom: Lactose fermentation occurred (white); no clearing or clotting. E. aerogenes, E. coli, K. pneumoniae, S. aureus
3) Middle: No fermentation, clearing, or clotting. S. sonnei, E. faecalis, Cx.

Question 22

Which bacteria does slow fermentation and gives a purple LM result?

Answer 22

S. enteritidis

Question 23

1) What test is this?
2) What did bacteria do in the top tube? What species do this?
3) What did bacteria do in the bottom tube? What species do this?

Answer 23

1) Phenylalanine deaminase (PHE)
2) Nothing occurred. E. coli, S. mitis, E. aerogenes.
3) Bacteria has phenylalanine deaminase, and reduced phenylalanine into PPA, which reacted with ferric chloride and turned dark green. P. vulgaris.

Question 24

1) What test is this?
2) What bacteria is in the plate on the left? Describe the colony morphology.
3) What bacteria is in the right? Describe the colony morphology

Answer 24

1) Mitis-Salivarius (MS)
2) Proteus vulgaris; has large mucoid colonies but reduced growth (because of tellurite in media)
3) E. faecalis; dark blue to black shiny colonies (S. mitis is the same)

Question 25

1) What test is this? 2) What bacteria is this? Describe the colony morphology 3) What enzyme is present in bacteria that can grow on this media?

Answer 25

1) MS 2) Alpha strep; has small colonies with abundant growth (streptococcus grows best on MS and is most resistant to crystal violet). 3) Saccharase (invertase)

Question 26

1) What test is this? 2) What did the bacteria do in the entirely yellow tube? What species does this? 3) What did the bacteria do in the tube with red? What species does this?

Answer 26

1) Sulfide Indole Motility (SIM) 2) No motility, no H2S formation, no indole formation. E. aerogenes. 3) Indole formation occurred (red); no motility or H2S formation. E. coli.

Question 27

1) What test is this? 2) What did the bacteria do in the top tube? What species does this? 3) What did the bacteria do in the bottom tube? What species does this?

Answer 27

1) SIM 2) H2S formation and motility occurred; no indole production. C. freundii. 3) Indole production (red), H2S formation, and motility occurred. Proteus vulgaris.

Question 28

1) What test is this? 2) Which tube is positive? Give an example of a species that does is. What occurs on the media? 3) Which is negative? Give an example of a species with this result.

Answer 28

1) Citrate 2) The bright blue tube: E. aerogenes grows on citrate and releases ammonium salts, increasing pH and turning bromothymol blue blue. 3) The green tube: E. coli.

Question 29

1) What test is this? 2) Which tube is positive? Give an example of a species that does this. What occurs on the media? 3) Which is negative? Give an example of a species with this result.

Answer 29

1) Methyl red. 2) The red tube is positive; E. coli does mixed-acid fermentation and lowers pH, causing methyl red to turn red. 3) The yellow tube is negative; E. aerogenes.

Question 30

1) What test is this? 2) Which tube is positive? Give an example of a species that does this. What occurs on the media? 3) Which is negative? Give an example of a species with this result.

Answer 30

1) Voges-Proskauer (VP) 2) The tube on the right (dark red/ purple); E. aerogenes performs alcoholic fermentation and produces acetylmethylcarbinol, which reacts with VP-A and VP-B. 3) The tube on the left (yellow); E. coli.

Question 31

1) What test is this? 2) Which tube is positive? What occurs on the media? 3) Which is negative?

Answer 31

1) ONPG 2) The tube on the right (yellow) is positive; the culture's B-galactosidase allowed for ONPG to be broken down (via lactose fermentation) into nitrophenol (yellow) and sugar. 3) The tube on the left (clear).

Question 32

1) What test is this? 2) Which tube is positive? Give an example of a species that does this. What occurs in the media? 3) Which is negative? Give an example of a species with this result.

Answer 32

1) Coagulase 2) The tube on the left (contains a clot); S. aureus. 3) The tube on the right; S. epi.

Question 33

1) What test is this? 2) Is a positive or negative example? 3) What happens during this test? 4) What species is negative for this test?

Answer 33

1) Catalase 2) A positive example (bubbles/ fizzing). 3) The enzyme catalase degrades toxic H2O2 4) Negative: Streptococci genus

Question 34

1) What test is this? 2) What does the test tube on the far left indicate? 3) What does the red test tube in the middle indicate? 4) What does the orange test tube on the right indicate? 5) What does the red test tube on the far right indicate?

Answer 34

1) NO3 (Nitrate) 2) Colorless before zinc: Proceed with zinc test. 3) Red before zinc: Nitrate reductase and NO2 are present 4) No change after zinc: Denitrification occurred; N2 present. 5) Red after zinc: Nothing has occurred; NO3 still present

Question 35

1) What test is this? 2) Which of the clear petri dishes is positive? Which is negative? 3) What side of the green petri dish is positive and which is negative? What is used to make it green?

Answer 35

1) DNase 2) Right one (zone of clearing around culture) is positive, left one is negative. 3) The right side (zone of clearing around culture) is positive, the left side is negative. Methyl green is used.

Question 36

1) What test is this? 2) Which tube is positive? What occurs in this tube? 3) Which tube is negative?

Answer 36

1) Nutrient Gelatin/ Gelatinase 2) The tube on top is positive; it remained liquid even when cold due to gelatinase breaking down gelatin. 3) The tube on the bottom is negative (becomes solid)

Question 37

1) What test is this? 2) Which plate is positive? What occurs on this plate? 3) Which plate is negative?

Answer 37

1) Nutrient starch (amylase) 2) The one on the left (zone of clearing) because the starch that has reacted with iodine has been broken down by amylase. 3) The one on the right (all dark purple)

Question 38

1) What test is this? 2) Which tube is positive? What occured in this tube? 3) Which tube is negative?

Answer 38

1) Urea 2) The pink tube; urease broke down urea into ammonia and CO2, which increased pH and caused phenol red to turn pink/purple. 3) The orange tube (stayed orange)

Question 39

1) What test is this? 2) Which tube is positive? What occured in this tube? 3) Which tube is negative?

Answer 39

1) Lysine Decarboxylase (LYS) 2) The purple tube; after glucose fermentation, lysine is broken down by lysine decarboxylase, which increases pH and causes the bromocresol purple to turn purple. 3) The yellow tube; glucose was fermented and the tube stayed yellow (acidic).