Gram-Positive vs Negative · Two Envelope Architectures
unseel.com · 1884 stain · purple vs pink
Gram+ PG 20–80 nm
Gram− PG ~7 nm
Stage two cell walls
Crystal violet (initial stain)
Safranin (counterstain)
Peptidoglycan layer
LPS / outer membrane
Unseel.com · Gram-Positive vs Negative