Dictionary > Gram-positive endospore-forming rods

Gram-positive endospore-forming rods

Definition
noun
A group of rod-shaped bacteria that are positive to Gram’s method and form endospores
Supplement
Gram-positive endospore-forming rods belong to a group of gram-positive bacteria. These bacteria are those whose cells appear violet rods under the microscope through Gram’s method in contrast to those bacteria that appear as spherical (gram-positive cocci) and to those that appear as pink cells (gram-negative bacteria). Gram-positive bacteria appear violet or blue under the microscope because the crystal violet dye fixed with the iodine mordant is retained in their outer covering. Gram-positive bacteria do not appear pink indicating that they did not take the safranin counterstain as gram-negative bacteria would. The main reason for this is the thick cell wall that gram-positive bacteria have. Their cell wall has a thick layer of peptidoglycan chains that cross-linked by the enzyme DD-transpeptidase. The rigid cell wall becomes dehydrated when treated with a decolorizing agent during gram staining. This prevents the efflux of initial stain. Thus, gram-positive bacteria remain violet even when a counterstain is introduced. Gram-positive bacteria may be cocci or bacilli depending on the cell shape. Gram-positive bacilli would appear violet rods after gram staining. Gram-positive bacilli may be endospore-forming or not. Endospores are structures indicating a dormant stage in certain bacteria. Gram-positive endospore-forming bacilli include Bacillus spp. and Clostridium spp.
See also:

Reference(s):

1 Madigan M; Martinko J (editors). (2005). Brock Biology of Microorganisms (11th ed.). Prentice Hall.


You will also like...

Buttress roots
Roots

This study guide tackles plant roots in greater detail. It delves into the development of plant roots, the root structur..

human brain structure
The Conscious & Unconscious Nervous System

This tutorial elaborates on how the nervous system works, particularly at the tissue level of the brain. There are three..

Circulation
Circulation

The circulatory system is key to the transport of vital biomolecules and nutrients throughout the body. Learn about the ..

Cell structure
Cell Structure

A typical eukaryotic cell is comprised of cytoplasm with different organelles, such as nucleus, endoplasmic reticulum, G..

squirrel
Animal Water Regulation

Animals adapt to their environment in aspects of anatomy, physiology, and behavior. This tutorial will help you understa..

Regulation of Biological Systems
Regulation of Biological Systems

Regulation of Biological Systems tutorials are focused on the modulation of biological systems from cell to population l..