McGraw Hill Quantitative Dilution of Bacteria

Different samples have different kinds and amounts of bacteria.

True.

We dilute and count bacteria to estimate how many are in a sample.

True.

The aseptic technique is important to keep everything clean and avoid contamination.

True.

To study one type of bacteria, we need a pure culture with no other germs mixed in.

True.

Serial dilution helps lower the number of bacteria so we can count them easier.

True.

The Standard Plate Count (SPC) method is used to grow and count bacterial colonies.

True.

We only count plates that have between 30-300 colonies for accurate results.

True.

What are the first two steps of the SPC method?

Do a serial dilution into tubes and transfer a small amount onto agar plates.

How do you spread bacteria on an agar plate during SPC?

Spread it using a "hockey stick" tool.

Why are plates incubated upside down in the SPC method?

To stop water drops from messing up results.

Where should you label the agar plate?

Label the bottom, not the lid, to avoid mixing things up.