How do bacillus and cocci differ on agar?

Answer 1

That really depends on what agar you are growing them on. If you are using growing agars such as BHI or blood, both will grow, and you won't be able to tell the difference when looking at them on the plate. If you use a selective agar that, lets say, will only grow cocci, then the bacilli won't grow. Or vice versa, if your selective agar only grows bacilli, then the cocci won't grow. If you use a differential agar, it may turn one a different color than the other -- for example, it may turn the bacillus blue, and the cocci may turn red. It is all dependent on the media you choose to grow your samples.

Answer 2

Bacillus and cocci bacteria differ in their shape and arrangement on agar plates. Bacillus bacteria are rod-shaped and typically form clusters or chains, while cocci bacteria are spherical and can form clusters, chains, or pairs on the agar surface. Additionally, Bacillus bacteria may produce colonies that appear irregular in shape, whereas cocci bacteria tend to form colonies that are more circular or oval-shaped.