How do I know if a point mutation is in the plasmid or in the chromosome of the bacteria?

Question

How do I know if a point mutation is in the plasmid or in the chromosome of the bacteria?

Answer 1

Easiest way is probably to isolate the plasmid from the bacteria and transfer it to a fresh batch of bacteria. If the phenotype associated with the mutation transfers to the new bacteria, then the mutation must be in the plasmid. If not, it's probably in the chromosome of the original bacteria.