Liquid growth media that contain antibiotics should be sterilized using which method?

• A. Dry heat sterilization
• B. UV irradiation
• C. Autoclaving
• D. Filtration

Answer: (D)

Verified step by step guidance

1. Understand the nature of liquid growth media containing antibiotics: antibiotics are often heat-sensitive and can be inactivated or degraded by high temperatures.
2. Review common sterilization methods: Dry heat sterilization uses high temperatures for extended periods, which can damage heat-sensitive compounds; UV irradiation is surface-limited and not effective for sterilizing liquids thoroughly; autoclaving uses moist heat under pressure, which can also degrade antibiotics.
3. Recognize that filtration sterilization involves passing the liquid through a membrane filter with pores small enough (usually 0.22 micrometers) to remove bacteria and other microorganisms without applying heat.
4. Conclude that filtration is the preferred method for sterilizing liquid media containing antibiotics because it preserves the antibiotic's activity while effectively removing contaminants.
5. Summarize that the correct sterilization method for antibiotic-containing liquid media is filtration, not dry heat, UV irradiation, or autoclaving.