Gram-positive

Bacteria that are gram-positive are stained dark blue or violet by Gram staining, in contrast to Gram-negative bacteria. The stain is caused by a higher amount of peptidoglycan in the cell wall, which typically lacks the secondary membrane and lipopolysaccharide[?] layer found in other bacteria.

The largest group of Gram-positive bacteria are the Firmicutes; well-known genera include Bacillus, Listeria[?], Staphylococcus, Streptococcus, Enterococcus, and Clostridium[?]. Other major groups include the Actinobacteria, Planctomycetes[?], Deinococci[?], and Thermotogae[?].