Question

The mechanism of killing of bacteria in autoclaving process is

• A. Oxidising proteins
• B. Alkylating essential materials
• C. Coagulation of proteins
• D. Radiation

Hint:

Autoclaving uses high-pressure steam to kill bacteria by causing the coagulation of proteins within the bacterial cells.

Answer 1

The Correct Option is C

Autoclaving uses moist heat, and the mechanism for moist heat sterilization can be checked directly.

1. Oxidising proteins: This is a chemical sterilant mechanism, not a moist-heat one.
2. Alkylating essential materials: This describes gas sterilants like ethylene oxide, not autoclaving.
3. Coagulation of proteins: Correct - moist heat denatures and coagulates microbial proteins, killing the cell.
4. Radiation: This is a completely different sterilization method, unrelated to autoclaving.

So the correct answer is Coagulation of proteins.

Answer 2

A helpful way to reason through this is with a simple everyday analogy - what happens to an egg when it's boiled - and then use that to test each option.

1. Oxidising proteins: Boiling an egg does not work by chemically oxidizing its proteins; it works by heat alone, so an oxidation-based mechanism doesn't match how boiling changes an egg, and by the same logic it doesn't match autoclaving either.
2. Alkylating essential materials: Alkylation requires a reactive chemical agent bonding to molecules; boiling water contains no such alkylating chemical, so this doesn't fit a purely heat-based process like autoclaving.
3. Coagulation of proteins: When an egg is boiled, its proteins unfold and coagulate into a solid, and this is exactly the same physical change moist heat causes in microbial proteins during autoclaving.
4. Radiation: Boiling an egg involves no radiation at all, only heat and moisture, so radiation-based killing does not correspond to autoclaving.

The everyday cooking analogy points to the same underlying mechanism as autoclaving.

Hence, the correct answer is Coagulation of proteins.