Assume you stain Bacillus by applying malachite green with heat and then counterstain with safranin. Through the microscope, the green structures are
a. cell walls.
b. capsules.
c. endospores.
d. flagella.
e. impossible to identify.

Verified step by step guidance

1. Identify the staining technique used: The problem describes a staining process involving malachite green and safranin, which is known as the Schaeffer-Fulton endospore stain.
2. Understand the purpose of each stain: Malachite green is used to stain endospores, while safranin is used as a counterstain to color the vegetative cells.
3. Recognize the role of heat: Heat is applied to help the malachite green penetrate the tough outer layer of the endospores, allowing them to retain the green color.
4. Determine the appearance under the microscope: After staining, endospores will appear green due to the retention of malachite green, while the rest of the cell will appear pink or red from the safranin.
5. Conclude the identity of the green structures: Based on the staining technique and the appearance of the structures, the green structures observed are endospores.

Key Concepts

Endospore Staining

Endospore staining is a differential staining technique used to identify bacterial endospores, which are resistant structures formed by some bacteria to survive harsh conditions. The malachite green stain penetrates the endospores when heat is applied, allowing them to retain the green color, while the safranin counterstain colors the vegetative cells pink.

Malachite Green

Malachite green is a dye commonly used in microbiology to stain endospores. Its application, especially with heat, facilitates the dye's penetration into the tough outer layer of the endospore, making it visible under a microscope. This property is crucial for distinguishing endospores from other cellular structures.

Counterstaining

Counterstaining is a technique used in microscopy to provide contrast to the primary stain. In this case, safranin is used after malachite green to stain the vegetative cells, allowing for differentiation between the green-stained endospores and the pink-stained cells. This helps in visualizing and identifying different cellular components.