You do a gram stain with a pure culture of m luteus. when you look at the cells, half of the cells are purple.

The complete question is - You do a gram stain of M. luteus, but see that there are cells present that are both purple and red. Explain what you see.

Answer:

The culture might be stained with safranin too long or it might be destained too much.

Explanation:

M. luteum is a gram-positive bacteria therefore in gram staining it must look purple under the microscope. So if half of the M. luteum pure culture looks red and half looks purple than there must be some mistake in the gram staining process.

The gram-positive bacteria can look pink if safranin is put for too much time so in this case some bacteria can look pink by absorbing safranin. Another probability is if we destain the culture too much the bacteria can lose their crystal violet and take safranin. So in these cases, some gram-positive bacteria can appear pink.