Lab Quiz 3 Flashcards
What is the purpose of the decarboxylase test?
5-11: Decarboxylase
To determine whether or not bacteria can decarboxylate lysine or ornithine
What is the name of the medium?
5-11: Decarboxylase
Lysine/ornothine broth
- LDC or ODC
What is the substrate, bacterial enzyme, and end product?
5-11: Decarboxylase
Substrate: Lysine or Ornothine
Bacterial Enzyme: Lysine or Ornothine Decarboxylase (endoenzyme)
End Products: Cataverine or putrescine (alkaline diamines) + CO2 g
What is the appearance of a positive/negative?
5-11: Decarboxylase
Positive: Purple/gray
Negative: Yellow
What is the reagent and pH indicator?
5-11: Decarboxylase
- None
- Bromocresol purple
What else is important about this test? (4)
5-11: Decarboxylase
- Results cannot be read before 48H
- Anaerobic enzymes
- Decarboxylation is anaerobic (oil used)
- Glucose is used first then acids which activate decarboxylase enzymes
What is the purpose of the deaminase test?
5-12: Deaminase
To determine whether bacteria can deaminate phenylalanine
What is the name of the medium?
5-12: Deaminase
Phenylalanine agar
What is the substrate, bacterial enzyme, and end product?
5-12: Deaminase
Substrate: Phenylalanine
Bacterial enzyme: Phenolalanine deaminase (endoenzyme)
End product: Ammonia + phenylpyruvic acid
What is the appearance of a positive/negative?
5-12: Deaminase
Positive: Green
Negative: Yellow
What is the reagent and pH indicator?
5-12: Deaminase
Reagent: Ferric Chloride (FeCl3) (indicates phenols)
pH indicator: None
Is protein deamination and decarboxylation an anaerobic or aerobic process?
Deamination - aerobic
Decarboxylation - anaerobic
What else is important about this test?(2)
5-12: Deaminase
- pH products neutralize eachother
- Aerobic enzyme
What is the purpose of the casease test?
5-16: Casease
To determine whether bacteria can hydrolyze casein
What is the name of the medium?
5-16: Casease
Milk agar
What is the substrate, bacterial enzyme and end products?
5-16: Casease
Substrate: Casein
Bacterial enzyme: Casease (exoenzyme)
End products: AA + Polypeptides
What is a positive/negative result?
5-16: Casease
Positive: Clear zone
Negative: White
Are there reagents or pH indicators?
5-16: Casease
None
What else is important about this test?(1)
5-16: Casease
- Both + and - organisms still grow
What is the purpose of the urease test?
5-18 Urease
To determine if bacteria can hydrolyze urea
What is the name of the medium?
5-18 Urease
Urea tablet
What is the substrate, bacterial enzyme, and end products?
5-18 Urease
Substrate: Urea
Bacterial enzyme: Urease
End products: Ammonia + CO2 g
What is a positive/negative result?
5-18 Urease
Positive: Pink
Negative: Yellow
What are the reagents an pH indicators?
5-18 Urease
None
Phenol Red
What else is important about this test?(2)
5-18 Urease
- Ammonia burns mucous membranes and neutralizes stomach acid
- H. pylori
What is the purpose of the TSI agar test?
5-21: TSI Agar H2S test
To differentiate bacteria on the basis
of glucose fermentation, lactose fermentation, sucrose fermentation, and sulfur reduction
What is the name of the medium?
5-21: TSI Agar H2S test
TSI agar
What are the substrates, bacterial enzymes, and end products?
5-21: TSI Agar H2S test
Substrates: Cystine + Sodium thiosulfate
Bacterial enzyme: Cystine desulfurase + Thiosulfate reductase (endoenzymes)
End product: H2S
What is a positive/negative result?
5-21: TSI Agar H2S test
Positive: Any black
Negative: No Black
What is the reagent and H2S indicator?
5-21: TSI Agar H2S test
No reagent
Ferrous ammonium sulfate
What else is important to consider?(1)
5-21: TSI Agar H2S test
Black color indicates an acidic pH
What is the name of the medium?
5-21: TSI Agar pH test
TSI agar
What are the substrates, bacterial enzymes, and end products?
5-21: TSI Agar pH test
Substrates: Glucose, Lactose, Sucrose
Bacterial enzymes: Various endoenzymes
End products: Acids
What does a positive/negative result look like?
5-21: TSI Agar pH test
Positive: Some yellow (glucose only)
Positive: All yellow (glucose plus at least one dissacharide)
Negative: No yellow or black
What are the reagents and pH indicator used?
5-21: TSI Agar pH test
None
Phenol Red
What else is important about this test?(1)
5-21: TSI Agar pH test
- In glucose only ferm. (K/A slant) glucose was in low % and runs out, peptones are then used aerobically
What are the results of this test?
5-21: TSI Agar HS2 and pH
- K/A H2S-
- A/A H2S-
- K/K H2S-
- K/K H2S-
- A/A H2S+
- K/A H2S+
What is the purpose of the oxidase test?
5-7: Oxidase
To test bacteria for oxidase enzyme
What is the name of the medium?
5-7: Oxidase
Nutrient agar
What is the substrate, bacterial enzyme, and end product?
5-7: Oxidase
Substrate: O2
Bacterial enzyme: Cytochrome C oxidase (endoenzyme)
End product: H2O
What is a positive/negative result?
5-7: Oxidase
Positive: Red/pink
Negative: No change
What is the reagent and pH indicator?
5-7: Oxidase
Oxidase reagent
None
What is the purpose of the catalase test?
5-6: Catalase
To test bacteria for the catalase enzyme
What is the name of the medium?
5-6: Catalase
Nutrient agar
What is the substrate, bacterial enzyme, and end products?
5-6: Catalase
Substrate: H2O2
Bacterial enzyme: Catalase (endoenzyme)
End products: H2O + O2 g
What is a positive/ negative result?
5-6: Catalase
Positive: Bubbling
Negative: No bubbles
What reagent and pH indicator were used?
5-6: Catalase
H2O2
None
What is the purpose of the anaerobic jar test?
2-8: Anaerobic Jar
To determine the oxygen requirements of an organism
What is the name of the medium?
2-8: Anaerobic Jar
Nutrient agar
What is the substrate, chemical, and end product?
2-8: Anaerobic Jar
Substrate: O2
Chemical: Anaerogen chemical
End product: H2O
What is a positive/negative result?
2-8: Anaerobic Jar
Positive: Growth
Negative: No growth
What is the purpose of the thiobroth test?
2-7: Thiobroth
To determine the O2 requirements of
an organism
What is the name of the medium?
2-7: Thiobroth
Thio broth
What is the purpose of the sodium thioglycollate and L-cystine in the recipe?
2-7: Thiobroth
Remove O2 to make anaerobic environment (turned to water)
What do these results mean?
2-7: Thiobroth
- Growth only at top means the organism is a obligate aerobe
- Growth at top and in stab means the organism is a facultative anaerobe
- Growth only in the stab means obligate anaerobe
- Thin growth near the top means organism is a microaerophile
What enzyme is present in aerobic bacteria? Anaerobic?
2-7: Thiobroth
Superoxide dismutase - aerobic
Catalase - anaerobic
