An acid-fast stain that does not use heat as the mordant is which of the following?

The Kinyoun stain is an acid-fast staining technique that does not require heat as a mordant. This method utilizes a higher concentration of the primary stain, usually carbolfuchsin, allowing the colors to penetrate the thick waxy cell wall of acid-fast bacteria, such as Mycobacterium. Since heat is not applied, the process relies more heavily on the chemical properties of the stain itself to achieve the desired results.

In contrast, the other staining methods mentioned either involve heat or are not specifically used for acid-fast staining. For example, the Truant fluorochrom stain and Gomori stain cater to different types of microorganisms or use distinct staining principles, often not focusing on acid-fast bacteria. Recognizing the unique characteristics of these staining techniques is crucial in identifying and properly classifying bacterial species in bacteriology.