Question

How would you determine whether a colony is a contaminant or real bacterial culture?

Answer 1

No it's not so a colony can infected by real bacteria culture.

Answer 2

Answer:

1. Perform Gram staining and look at the morphology of the bacterial cells, if contaminated more than one cell type shall be visible.

2. Streak the culture on a suitable agar based medium and observe color and type of cfus.

Explanation:

If Bacillus sp. you are using, heat the culture at 80 C for 10 min and culture on a suitable medium. Most contaminating non sporulating cells will be killed and bacilli survive