Chapter 18.1, Problem 2TQ

Summary Introduction

To review:

The group of bacteria that are stained either by Gram-positive stain or by the Gram-negative stain and the group of bacteria that are stained by both. Also, mention the group for which the Gram stain is undefined.

Introduction:

Gram-positive bacteria take up the crystal violet stain. When viewed through an optical microscope, they appear to be purple in color. The thick peptidoglycan layer in the bacterial cell wall after being washed away still retains the stain. The Gram-negative bacteria are unable to retain the violet stain. The peptidoglycan layer in Gram-negative species is much thicker.