Gram-positive bacteria retain the primary crystal violet stain that is applied in the Gram stain because of the cross-linking of the thick peptidoglycan layer in their cell walls. Their cell walls contain less lipids than that of a gram-negative bacteria, and this reduces the permeability of their cell wall to the organic solvents that are used as a decolorizer. When the counterstain is added, it may enter the gram-positive cell, but does not change the color of the cells.

A thick peptidoglycan is MOST often associated with which of the following types of bacteria?