Expected Results + Bacteria

ALL EXPERIMENTS

What was the expected of raw milk in exp 1?

High microbe count

What was the expected of pasteurized milk in exp 1?

Low microbe count

What was the expected of past-date pasteurized milk in exp 1?

Second highest microbe count

Why does pasteurized have the lowest count?

Pasteurization removes most microbes for safe consumption and increases the shelf life (lag phase).

What was the expected of raw milk in exp 2?

High CFU/ml count

What was the expected of pasteurized milk in exp 2?

Low CFU/mll count

What does a high CFU/ml count indicate?

Many microbes present, so poor quality/unsafe milk

What does a low CFUU/ml count indicate?

Small traces of microbes, so good quality/safe milk

What bacteria was mentioned in exp 3?

• Lactic-acid producing

• Gas producing

• Spoilage causing

What genera of bacteria are lactic-acid producing?

• Streptococcus

• Lactobacillus

What bacteria are gas producing?

• Clostridium

• Coliforms → Escherichia coli and Klebsiella aerogenes

What bacteria are spoilage causing?

• Geotrichum

• Cladosporium

• Penicillin

What are the properties of APT agar?

Non-selective but permits the growth of 2 microorganisms

What 2 microorganisms are permitted to grow on APT agar?

• Streptococcus

• Lactobacillus

What are the properties of EMB agar?

• Differential (between lactose/non-lactose fermenting)

• Selective (doesn’t let G+ grow)

What grows on EMG agar?

• E. coli

• K. aerogenes

What does E. coli look like on EMG agar?

Green metallic sheen and is lactose fermenting

What does K. aerogenes (enterobacter) look like on EMG agar?

Pink/purple and is non-lactose fermenting

What bacteria was mentioned in exp 4?

• Staphylococcus aureus (toxin producing)

• Salmonella sp. (pathogenic microorganism)

What does growth on Staphylococcus 110 look like?

white-yellow colonies

• Selective (doesn’t let anything except for staph grow)

• Differential (S. aureus from others)

What is a positive result of the coagulase test?

Heavy firm clot

What is a positive result of the coagulase test indicative of?

S. aureus bc of their coagulase enzyme

What is a negative result of the coagulase test?

No clot

What is a negative result of the coagulase test indicative of?

Salmonella sp.

What does Salmonella sp. look like on MacConkey agar?

White-pink colonies and is non-lactose fermenting

What are the results of TSI slant for Salmonella sp.?

1) Lactose/sucrose use = red slant (-)

2) Dextrose use = yellow butt (+)

3) H2S production = blackening of butt (+)

4) Gas production = gas in medium (+)

Salmonella sp. (-+++)

What does a positive of lactose/sucrose use of TSI look like?

yellow slant (+)

What does a negative of dextrose use, H2S, and gas production on TSI look like?

no change in the medium

What bacteria was mentioned in exp 5?

Coliforms → E. coli and K. aerogenes

What are the results of the presumptive and confirmed test?

• (+) = gas formation in Durham tube

• (-) = no gas formation

What agar was used for the alternative confirmed test?

EMB agar

What did the coliforms look like on EMB agar in the alternative test?

• E.coli → green metallic sheen + flat colonies

• K. aerogenes → non-metallic, gummy, large, mucoid

What bacteria was mentioned in exp 6?

Coliforms → Total and fecal

What medium was used in exp 6?

• Endo agar → total

• mFC with BCIG → fecal

What did the total coliforms look like on Endo agar?

Green sheen + lactose fermenting

What did the fecal coliforms look like on mFC agar?

Blue colonies → indicative of warm-blooded animal contamination

What bacteria were mentioned in exp 7?

• E. coli

• Salmonella typhimurium

• Pseudomonas aeruginosa

• Citrobacter freundii

• Bacillus suubtillis

• Staphylococcus aureus

What did E.coli look like on EMB, ENDO, and Nutrient agar?

1) EMB → ++ green sheen

2) ENDO → ++ dark pink and green sheen

3) Nutrient → ++

What did S. typhimurium look like on EMB, ENDO, and Nutrient agar?

1) EMB → + colourless/pale pink

2) ENDO → ++ pale pink

3) Nutrient → +

What did P. aeruginosa look like on EMB, ENDO, and Nutrient agar?

1) EMB → + colourless/pale pink

2) ENDO → + pale pink

3) Nutrient → + fluorescent green

What did C. freundii look like on EMB, ENDO, and Nutrient agar?

1) EMB → ++ green sheen

2) ENDO → ++ dark pink green sheen

3) Nutrient → +

What did B. subtilis look like on EMB, ENDO, and Nutrient agar?

1) EMB → - possible traces

2) ENDO → -

3) Nutrient → + irregular margin

What did S. aureus look like on EMB, ENDO, and Nutrient agar?

1) EMB → - possible traces

2) ENDO → -

3) Nutrient → + yellow

What bacteria were mentioned in exp 8?

• E. coli

• K. aerogenes

• C. freundii

What is a positive result of the indole test?

red layer @ top of tube (negative is no change)

What are the results of the methyl red test?

1) positive → red (pH<4.5)

2) negative → yellow (pH>4.5)

What are the results of the Vi test?

1) positive → cherry red

2) negative → brown

What is a positive result of the indole test?

slant turns blue (negative is no change)

What are the results of E. coli for the IMViC test?

1) I → +

2) M → +

3) Vi → -

4) C → -

What are the results of K. aerogenes for the IMViC test?

1) I → -

2) M → -

3) Vi → +

4) C → +

What are the results of C. freundii for the IMViC test?

1) I → -

2) M → +

3) Vi → -

4) C → +

What bacteria was mentioned in exp 9?

E. coli

What did the Sample A (demand) tube look like?

yellow and gas production

What did the Sample B (demand-free) tube look like?

purple and no gas production

What did the Sample C (control) tube look like?

yellow and gas production

What was the growth of E. coli in Sample A?

+++

What was the growth of E. coli in Sample B?

-

What was the growth of E. coli in Sample C?

+++

What bacteria were mentioned in exp 11?

Nitrosomonas europa and Nitrobacter agilis

What are the results of Nessler’s reagent (Ammonia test)?

1) Large amount of ammonia = brown (+++)

2) Moderate NH4 = deep orange-yellow (++)

3) Small NH4 = pale yellow (+)

4) No NH4 = no colour (-)

What are the results of Tromsdorff reagent (Nitrite test)?

1) Large amount of NO2 = dark blue-black (++++)

2) Moderate NO2 = deep blue (+++)

3) Small NO2 = pale blue (++/+)

4) No NO2 = no colour (-)

What is the results of the Diphenylamine reagent?

Dark blue after 30 seconds

What bacteria was mentioned in exp 12?

P. aeruginosa

What are the results of exp 12?

1) Uninoculated → no gas (-)

2) P. aeruginosa → gas (+)

3) Soil → gas (+)

What bacteria were mentioned in exp 13?

• Bacillus cereus

• Pseudomonas fluorescens

• Proteus vulgaris

What are the results of bromothymol blue indicator?

1) Neutral (-) = green

2) Low NH4 (+) = pale blue

3) Moderate (++) = blue

4) Large (+++) = dark blue

5) pH<6.5 = yellow

What is the results of urea hydrolysis?

yellow to pink = pH>8.1

What bacteria were mentioned in exp 14?

Azotobacter vinelandii

What are the characteristics of Azotobacter chroococcum?

• Large ovoid rod

• Found in pairs

• NO water-soluble pigment

• NO fluorescence under UV

• Growth on agar = water-insoluble pigment

  • Strains later become black

What are the characteristics of Azotobacter beijerinckii?

• Similar in size + shape to A. chroococcum

• Single, pairs or chains of several cells w large capsules

• NO fluoresce under UV

What are the characteristics of older Azotobacter beijerinckii cultures?

• Coccoid

• Form cysts

• Turn yellow/cinnamon w water-insoluble pigment

What are the characteristics of Azotobacter vinelandii?

• Large ovoid rod

• Found in pairs

• NO water-insoluble pigment

• Water-soluble fluorescent pigment appears green under UV

What are the characteristics of Azotobacter paspali?

• Large ovoid OR pleomorphic rod

• Variations from coccoid to elongated filaments

• Water-soluble fluorescent pigment appears green under UV

• NO water-insoluble pigment

What are characteristics of Azomonas?

• Large ovoid cells

• In pairs OR clumps

• Capable of nitrogen fixation

• No cysts are produces

• Some strains has a water-soluble fluorescent pigment appearing white under UV

What bacteria was mentioned in exp 15?

Rhizobium sp.

What do the nodules look like under the microscope?

Long irregular rods/x and y forms

What does the slant look like under the microscope?

Gram -ve pink rods (bacillus)

What bacteria was mentioned in exp 16?

Acidithiobacillus thiooxidans

What is a positive indication of H2SO4 production?

pH < initial pH

What bacteria was mentioned in exp 17?

Desulfovibrio desulfuricans

What is an indicator of sulfate reduction?

The blackening of ATCC medium

What are the results of exp 17?

1) Uninoculated → -

2) Aquifer water → +

3) Desulfovibrio desulfuricans → +

What bacteria were mentioned in exp 18?

• E. coli

• Bacteriophage T2

What bacteria was mentioned in exp 19?

DH5alpha E. coli

What are the results of exp 19?

1) Sample A (negative control) → NO blue or white colonies

2) Sample B (reaction control) → ONLY white colonies

3) Sample C (experimental control) → blue AND white colonies

What bacteria was mentioned in exp 20?

Foliose lichens