SPC

Question 1

What are the three ways to quantify bacteria?

Answer 1

Direct microscopic counts, turbidometric methods, and standard plate counts

Question 2

What are direct microscopic counts?

Answer 2

1. Sample is placed on a special slide and bacteria are counted.
2. It is fast
3. Both dead/ alive bacteria are counted

Question 3

What are turbidometric methods?

Answer 3

1. Based on turbidity (cloudiness)
2. Requires spectrophotometer
3. Both dead/ alive are counted

Question 4

What is standard plate count (SPC)?

Answer 4

1. Sample diluted, aliquated and grown on plates
2. Requires incubation
3. Only counting live bacteria

Question 5

What is the procedure for SPC?

Answer 5

Serial dilutions are conducted to obtain a countable number of colonies (30-300)

Known volume of diluted sample is plated

Incubation

Count CFU

Original cell density (OCD) is determined “tiger”

Question 6

How does one calculate OCD?

Answer 6

OCD= # of colonies/ amount plated (mL) X dilution of the amount plated