Question

1)An eosin methylene blue (EMB) agar plate was inoculated with four different species of bacteria. Below are the colony growth after inoculation.

Which shows a vigorous lactose fermenter?

A) A brown media with an oblong culture of bacteria. The colony shows vigorous growth and is the same color as the media.

B) A brown media with an oblong colony of bacteria that experiences weak growth. The color of the media is visible through the translucent white color of the bacterial colony

C) A brown media with an oblong colony of bacteria that experienced vigorous growth. The colony is pink with a green sheen and bile salt precipitate.

D) A brown media with an oblong discoloration where it was inoculated with bacteria.

2)

An eosin methylene blue (EMB) agar plate was inoculated with four different species of bacteria. Below are the colony growth after inoculation.

Which shows only a faint discoloration of the media where the colony was inoculated and no growth occurred?

A) A brown media with an oblong discoloration where it was inoculated with bacteria.

B) A brown media with an oblong culture of bacteria. The colony shows vigorous growth and is the same color as the media.

C) A brown media with an oblong colony of bacteria that experiences weak growth. The color of the media is visible through the translucent white color of the bacterial colony.

D) A brown media with an oblong colony of bacteria that experienced vigorous growth. The colony is pink with a green sheen and bile salt precipitate.

3) Below are two cultures of two different bacteria, both grown on MacConkey Agar. Which colony of bacteria is is gram negative but not capable of fermenting lactose?

A) A reddish purple media with an oblong colony of bacteria growing on it. The colony is a pink color and bile salts are visible

B) A reddish purple media with an oblong colony of bacteria growing on it. The colony is the same color as the media.

4) Below are two different organisms grown on mannitol salts agar (MSA). What is of a member of the genus Staphylococcus, other than Staphylococcus aureus?

A) A dark pink media with an oblong colony of bacteria the same color as the media growing on it.

B) A dark pink media with an oblong colony of bacteria surrounded by a yellow halo growing on it.

Answer 1

Q 1 and 2 are Same and Correct answer is

Option C: "A brown media with an oblong colony..............................................bile salt precipitate" in fermenter produces acid (low pH), give purple or pink color and this dye have potential to inhibit the grow of gram positive bacteria. Rest of the options are not relevant.

3. B is not capable of fermenting lactose as A is having gram negative bacteria, but also potential for lactose fermentation. So "B" would be correct option.

4. A "A dark pink..............on it" and S. aureus will give a phenotype which is mentioned in "B' turn yellow, which is a characteristic feature of this strain. So, the correct option is "A'