Peptidoglycan is a polymer found in bacteria cell walls responsible for gram staining and maintaining shape and protection. Gram-positive bacteria have a thick layer, while gram-negative have a thinner layer encased in lipids. The staining process can provide information on structure and identification. Pseudopeptidoglycan is similar but resists lysozymes, allowing bacteria to spread. The process can also visualize the structure of bacteria under a microscope.
Peptidoglycan is a type of polymer found in the cell walls of bacteria. This polymer is responsible for the phenomenon known as gram staining, in which certain types of bacteria acquire a rich purple color when exposed to the crystal violet dye, and performs a number of important biological functions for the organisms it encloses. Besides being very visually interesting, the gram staining process can provide important information on the structure of the bacteria under investigation and can be used as a key identification tool.
This polymer, also known as murein, is made up of cross-linked chains of sugars and amino acids. Forms a rigid matrix which contributes to the integrity of the bacterium. While peptidoglycan cell walls will not determine the shape of an organism, they will help it maintain its shape, ensuring it is not compromised. They also provide protection from external forces that could threaten the bacteria, such as antibiotic drugs.
In gram positive bacteria, the cell wall is made up of a very thick layer of peptidoglycan which will clearly retain the color of a gram stain. Gram-negative bacteria have a thinner layer of peptidoglycan, encased in a layer of lipids, and will turn pink when exposed to crystal violet. By looking at the color of a bacterium, a scientist can learn the structure of its cell wall, which may provide a clue as to the bacterium’s identity or which compounds could be used to eliminate it.
In addition to providing basic information about cell wall structure, a Gram stain can also be used to visualize the structure of a bacterium under a microscope. An organism rich in peptidoglycans will be highlighted with the dye, creating a very detailed, sharp, high-contrast image that can be used to glean information about what the organism looks like inside. This information can be used to learn more about how bacteria work and to glean further clues about the identity of an organism under investigation.
A similar compound called pseudopeptidoglycan or pseudomurein is similar in chemical structure to peptidoglycan, but not identical. Pseudopeptidoglycan can be found in addition to peptidoglycan in the cell walls of some bacteria. This polymer resists specialized enzymes known as lysozymes, which are designed to break down the cell wall so that a bacterium dies. Bacteria that can resist lysozymes have a better chance of resisting the onslaught of an active immune system, which will allow the organisms to spread.
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