University of Santo Tomas
College of Science
Department of Biological Sciences
WORKSHEET – MODULE 2
Preparation and Sterilization of Culture Media and Glasswares
Date
Group Number
List of Members
(Last name first)
Contribution
Data table
Medium &
components
Nutrient broth
(NB)
Manufacturer
specifications
Components:
Weigh _________ g for
1L
Nutrient agar
(NA)
Components:
Weigh _________ g for
1L
Potato dextrose
agar (PDA)
Components:
Weigh _________ g for
1L
Calculations (Use back side of page if needed)
To prepare: ____ x ______ mL tubes
Total volume needed: ____________mL
To prepare: ____ x ______ mL tubes (slant)
_______ plates
Total volume needed: ____________mL
To prepare: ____ plates
Total volume needed: ____________mL
This material is for your personal use as a student enrolled in this course. Reproduction and/or distribution is prohibited.
University of Santo Tomas
College of Science
Department of Biological Sciences
Guide questions
1. What is the purpose of the following components in bacteriological culture media? (Explain in
the context of the main elemental requirements of cells: Carbon, Hydrogen, Nitrogen, and
Oxygen)
• Peptone
• Yeast extract
• Beef extract
• Potato infusion
• Agar
2. Why should agar media be completely dissolved before they are dispensed in tubes and
plates?
This material is for your personal use as a student enrolled in this course. Reproduction and/or distribution is prohibited.
University of Santo Tomas
College of Science
Department of Biological Sciences
3. What are the bases for pegging the temperature at 1210C for 15-30 minutes during moist
heat sterilization and 1800C for two (2) hours using dry heat sterilization? 1.Can you
sterilize culture media using dry heat sterilization? Why is that so?
4. What is role of cotton plug in media prep, sterilization and culture of microorganisms?
5. Instead of using cotton plug, plastic screw-cap is used, can you substitute this for the former?
Is it technically acceptable in microbiology?
II. References (Follow the APA format)
This material is for your personal use as a student enrolled in this course. Reproduction and/or distribution is prohibited.