Question

How could you determine whether the turbidity in your LB tube was from a mixture of different bacteria or from the growth of only one kind of bacterium? Give a detailed explanation.

Answer 1

There is no way to tell that only one bacterium exits in the LB tube by just looking at it. To determine whether you have one typr or a mixed population of bacteria, would need to take a sample of the broth and place it on a agar dish or need to do a gram stain to determine it.

The simplest method is to use a sterile pipette to take a small amount from the turbid mixture, mix it with distilled water and view under microscope.

Use simple stain like 1% methylene blue/carbol fuschin/saffranin/crystal violet. Identify if there are different microbes by shape, size and staining property.