Which statement best describes the appearance of Micrococcus luteus when observed using a negative stain technique?

• A. Micrococcus luteus appears as yellow, spherical cells against a dark background.
• B. Micrococcus luteus appears as spiral-shaped cells stained darkly.
• C. Micrococcus luteus appears as rod-shaped cells with a clear background.
• D. Micrococcus luteus cannot be visualized using the negative stain technique.

Answer: (A)

Verified step by step guidance

1. Understand the principle of the negative stain technique: it stains the background but leaves the cells unstained or lightly stained, allowing the shape and arrangement of cells to be observed clearly against a dark background.
2. Recall the morphology of Micrococcus luteus: it is a Gram-positive bacterium that typically appears as spherical (coccus) cells arranged in clusters.
3. Consider the color characteristics of Micrococcus luteus: it is known for its yellow pigmentation, which can be visible under the microscope.
4. Analyze each option by matching the known morphology and staining characteristics of Micrococcus luteus with the description given in the negative stain context.
5. Conclude that the best description is the one that mentions yellow, spherical cells against a dark background, as this aligns with the morphology and pigmentation of Micrococcus luteus observed using a negative stain.