Culture media are sterilized by –
**Core Concept**
Autoclaving is a widely accepted method for sterilizing culture media in microbiology laboratories. This process involves subjecting the media to high pressure and temperature to kill all forms of microbial life.
**Why the Correct Answer is Right**
Autoclaving works by using steam under pressure to inactivate enzymes and disrupt cell membranes, ultimately leading to the death of microorganisms. The high temperature (usually 121°C) and pressure (usually 15 psi) ensure that all types of bacteria, viruses, and fungi are eliminated. Autoclaving is a reliable and effective method for sterilizing culture media, which is essential for maintaining the integrity of microbiological experiments and preventing contamination.
**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because dry heat sterilization, while effective for certain materials, is not suitable for culture media due to its slow and less effective killing action.
**Option B:** Gamma radiation is not commonly used for sterilizing culture media in microbiology laboratories, as it is costly and may not be readily available.
**Option C:** Ethylene oxide sterilization is typically used for heat-sensitive materials, such as plastics and some medical devices, but it is not the preferred method for sterilizing culture media.
**Clinical Pearl / High-Yield Fact**
Autoclaving is not only used for sterilizing culture media but also for equipment, such as pipettes and glassware, that come into contact with biological samples.
**Correct Answer: D. Autoclaving**