Question

1. What are the advantages of growing bacteria on a plate versus broth?
2. How can you tell whether the colonies on a plate are from the original culture and not contaminants?

Answer 1

Growing bacteria in a plate give the advantage over broth as if you have performed streak plate so you will get the separate colony and can easily distinguish the morphology of your desired bacteria from the contaminated ( different morphology) one and also you can pick individual colony of bacteria for further experients but in broth culture, it could be a disadvantage or if you perform spread plate culture and your plasmid has the selection marker so it a plus point towards getting the original colonies and very few or no contaminated colonies.

Also, in plate bacteria get sufficient nutrients( individual colonies ) as compare to broth culture.

and also it has been proven from different research that plates are better than broth in the recovery of the fastidious organism.