Which of the following techniques can be used to sterilize microbiological media?

• A. Refrigeration at 4 ^\circ C
• B. Incubation at 37 ^\circ C
• C. Filtration with a 10 μm filter
• D. Autoclaving

Answer: (D)

Verified step by step guidance

1. Understand the goal: sterilization means the complete elimination of all forms of microbial life, including spores, from the microbiological media.
2. Evaluate refrigeration at 4 ^\circ C: this technique slows down microbial growth but does not kill microbes, so it does not achieve sterilization.
3. Evaluate incubation at 37 ^\circ C: this temperature is optimal for many microbes to grow, so it cannot sterilize media; instead, it may promote microbial growth.
4. Evaluate filtration with a 10 \mu m filter: typical bacteria range from about 0.5 to 5 \mu m in size, so a 10 \mu m filter is too large to remove bacteria effectively and thus cannot sterilize the media.
5. Understand autoclaving: it uses high-pressure saturated steam at around 121 ^\circ C for a specific time to kill all microorganisms and spores, making it an effective sterilization method for microbiological media.