Quantitation of Cultured Microorganisms
Lab 6 Quantitation of Cultured Microorganisms - 100 points
Student Name: ………….
Student ID: ………
Course: BIOL202
✓ -Each question on the lab worksheet must be answered completely,
thoroughly, in complete sentences and correctly in order to be
considered for full credit
✓ -If the question asks you to do research or find a source, a reputable,
credible and/or scholarly source citation must be included in order to
be considered for full credit
✓ -If a math formula is required to arrive to an answer, work must be
shown otherwise, no credit will be awarded
Pre-Lab Questions
1. Question: A serial dilution of a sample has an unknown
concentration of microorganisms. A countable plate has 44
CFU. It was inoculated with 0.1 mL of a 10-1 dilution. What was
the population density of the original sample per milliliter? (10
points)
10−
- 44 1
x (calculate the power to simplify)
0.1ml
10
- 44 (multiply the numerator and denominator)
x 0.1ml
10 0
(simplify into single fraction)
- 44 ml
x
-100 44 x
= 4,400 CFU/ml
ml
2. Question: Compare and contrast the plate count methods for
bacterial and viral populations. (10 points)
`
Bacteria is identified through direct plate counts by colony forming unit (CFU). This
allows microbiologist to calculate colonies formed and they utilize the formula
CFU original CFU counted x dilution factor
, =
ml volume of culture plate(ml )
Viruses however cannot be traced on agar plates they must be identified utilizing plaque
assays. The virus must be diluted before obtaining a plate between 30 and 300 plaques
and utilize the plaque forming unit (PFU) . Both CFU and PFU share the same dilution
Lab 6 Quantitation of Cultured Microorganisms - 100 points
Student Name: ………….
Student ID: ………
Course: BIOL202
✓ -Each question on the lab worksheet must be answered completely,
thoroughly, in complete sentences and correctly in order to be
considered for full credit
✓ -If the question asks you to do research or find a source, a reputable,
credible and/or scholarly source citation must be included in order to
be considered for full credit
✓ -If a math formula is required to arrive to an answer, work must be
shown otherwise, no credit will be awarded
Pre-Lab Questions
1. Question: A serial dilution of a sample has an unknown
concentration of microorganisms. A countable plate has 44
CFU. It was inoculated with 0.1 mL of a 10-1 dilution. What was
the population density of the original sample per milliliter? (10
points)
10−
- 44 1
x (calculate the power to simplify)
0.1ml
10
- 44 (multiply the numerator and denominator)
x 0.1ml
10 0
(simplify into single fraction)
- 44 ml
x
-100 44 x
= 4,400 CFU/ml
ml
2. Question: Compare and contrast the plate count methods for
bacterial and viral populations. (10 points)
`
Bacteria is identified through direct plate counts by colony forming unit (CFU). This
allows microbiologist to calculate colonies formed and they utilize the formula
CFU original CFU counted x dilution factor
, =
ml volume of culture plate(ml )
Viruses however cannot be traced on agar plates they must be identified utilizing plaque
assays. The virus must be diluted before obtaining a plate between 30 and 300 plaques
and utilize the plaque forming unit (PFU) . Both CFU and PFU share the same dilution
