Systematics: bacteria ID

Question 1

What are the 3 disciplines of taxonomy?

Answer 1

• Classification: organises micro-o into groups based on morphologic, physiological, genetic traits
• Nomenclature: naming groups and members (Genus species)
• Identification: tests character. of unknown & compare w/ features of known micro-o => assigned into Genus & species

Question 2

What’s an obligate aerobe? and an e.g.

Answer 2

requires O2 to grow. E.g. Staphylococcus aureus

Question 3

What’s an obligate anaerobe? and an e.g.

Answer 3

grows in complete absence of O2 e.g. CLostridium perfringens

Question 4

What’s a facultative anaerobic (organism)? and an e.g.

Answer 4

grows w/ or w/out O2 e.g. Escherichia coli?

Question 5

What does microaerophilic mean? Name a genus

Answer 5

grows at low levels of O2 (compared to atmosphere). VIbrio?

Question 6

What’s a capnophile? Name a genus

Answer 6

aka carboxyphile. grows at hi levels of CO2. Neisseria and Haemophilus

Question 7

List Genus + species of an organism that is acid fast

Answer 7

Mycobacterium tuberculosis and M. leprae

Question 8

Which genera (genus) of bact. produce spores?

Answer 8

Bacillus and Clostridium

Question 9

When doing a catalase test why do you have to be careful of taking a colony from BA?

Answer 9

Bc BA will give a false positive result (it bubbles)

Question 10

What precautions do you need to take when performing an oxidase test?

Answer 10

Don’t use loops or wires containing iron = false postive result bc iron is e- donor. (use a toothpick)

Question 11

Explain principle of gram staining (how it works w/ GPos & GNeg)

Answer 11

0. Fixation w/ heat= bact. stick on slide
1. Crystal violet = GPos & GNeg stains purple
2. Lugol’s iodine = GPos & GNeg stains purple
3. (differentiation) Alcohol = purple GPos, clear GNEg bc crystal violet-iodine complex gets stuck in THICK peptidoglycan layer in GPos
4. Carbol fuchsin = GNeg stains pink

Question 12

Explain principle of action for catalase test? (How it works, what is happening) and name genus that is positive.

Answer 12

tests to see if catalase is in bact. by reacting w/ H2O2 -> O2 (bubble/fizz) + H2. e.g. Staphylococci

Question 13

Explain how to interpret Oxidation-Fermentation (OF) test

Answer 13

test determines if organism metabolises glucose by oxidation (loose lid= O2 present = aerobic metabolism) or fermentation (tight lid = O2 absent= anaerobic). Determined if bromothymol blue pH indicator (green) -> yellow bc acid produced

Question 14

In Cowan & Steel’s pheno. tables for bact. what does “+”, “-“, “d”, “S”, “R”, “C” and “W” represent?

Answer 14

\+ : 85-100% get positive result
- : 0-15% get a positive result
d : 16-84% get a positive result (can be GNeg or GPos)
S: sphere (cocci)
R: rod (baccili) 
C: curved
W: weak reaction

Question 15

1º identification of GPos bact. (4-10)

Answer 15

shape, catalase, oxidase, spores, O-F test, acid fastness, grows in an/aerobic, gluscose (acid)