Question

1. Describe three ways the spore can be used to differentiate between different Bacillus species.

2. An MCB301 student performed the catalase test on Streptococcus pyogenes growing on a plate of blood agar medium. They found bubbles forming and concluded the bacterium was catalase positive. Do you agree with their assessment? Describe what most likely happened during their testing.

Answer 1

Hi there, as per my guidelines, i would like to answer your first question.

The three parameters based on spore, that can be used to different between Bacillus species are;

1. Position of spores when sporulating-

a) Central- Bacillus anthracis , B.cereus, B.megaterium, B.subtilis, B.licheniformis , B.brevis

b) Terminal- B. circulans , B. sphaericus

2. Bulging of rods in sporulating forms-

a) Slight bulging- Bacillus anthracis, B.cereus, B. subtilis, B. licheniformis.

b) Sharp bulging observed- B. sphaericus, B. brevis, B. circulans

c) No bulging at all- B. megaterium, B. pumilus

3. Type for germination

a) Absorption of most of spore wall, enlargement, and return to vegetative form, spore case may persist as polar cap- Bacillus anthracis, B.cereus, B. megaterium (no polar caps)

b) Emergence of vegetative rod laterally, partial or complete splitting of spore case- B. subtilis, B, pumilus.

c) Emergence of vegetative rod but with no splitting of spore case- B. brevis, B. circulans , B. licheniformis

Hope this helps.