Question

When looking at various stains (i.e gram , acid fast), how do you differentiate between Micrococcus roseus and Lactococcus lactis?

Thank you

Answer 1

Both strains have the same staining results. So how would you differentiate by appearance?

Answer 2

I am not a microbiologist, just trying to suggest hints to <i>differentiate</i>, not identify.

They are both gram positive, but if you examine the physical appearance, M.roseus tend to be in tetrads, while L.lactis are in pairs. They seem to be quite distinctive in appearance, even though their sizes are similar.

See them for yourself in enlarged pictures at:
http://en.wikipedia.org/wiki/Micrococcus
http://en.wikipedia.org/wiki/Lactococcus_lactis