Here is a list of bacterial strains and their phenotypes: Strain 1: Salmonella w

ID: 8457 • Letter: H

Question

Here is a list of bacterial strains and their phenotypes:

Strain 1: Salmonella with auxotrophies for valine and vitamin B12
Strain 2: autotroph with an auxotrophy for valine
Strain 3: heterotroph with multiple amino acid auxotrophies
Strain 4: heterotroph unable to synthesize its own guanine for DNA synthesis or its own tryptophan
Strain 5: protoheterotroph that cannot use dextrose as its sole carbon/energy source

Fill in the table with the expected growth results for the various media using a + (represents the strain will grow) or a – (represents the inability of the strain to grow).

Media Available Strain 1 Strain 2 Strain 3 Strain 4 Strain 5

1)Minimal Media (MM)
2)MM + Dextrose (Dex)
3)MM + Dex + Leucine
4)MM + Dex + Valine (V)
5)MM + Dex + B12
6)MM + Dex + B12 + V
7)MM + Dex + Casamino Acids*
8)Tryptic Soy Yeast Extract Agar

*Casamino Acids: a mixture of amino acids and some very small peptides obtained from acid hydrolysis of casein – contains all essential amino acids except for tryptophan.

Explanation / Answer

Media available

Strain 1

Strain 2

Strain 3

Strain 4

Strain 5

1)Minimal Media (MM)

2)MM + Dextrose (Dex)

3)MM + Dex + Leucine

4)MM + Dex + Valine (V)

5)MM + Dex + B12

6)MM + Dex + B12 + V

7)MM + Dex + Casamino Acids*

8)Tryptic Soy Yeast Extract Agar