Gram-positive bacteria – The thick layer of Peptidoglycans is stained purple by the crystal violet dye, which is why gram-positive bacteria appear purple or blue. Peptidoglycans are the main contents of the cell walls of Gram-positive bacteria (almost 95%), while Gram-negative bacteria have an additional layer of phospholipids and lipopolysaccharides. Gram Negative Bacteria Gram positive and gram negative bacteriaīacteria are grouped as ‘Gram positive’ and ‘Gram negative’ bacteria, based on the results of Gram staining method. the scientific classification of organisms, they can be categorized into the following groups for simplification. Though bacteria are mainly classified into phylum i.e. In a broad sense, this bacterial classification includes bacteria which are found in various types of environment such as fresh-water bacteria, saline-water bacteria, bacteria that can survive extreme temperatures (as in sulfur-water-spring bacteria and bacteria found in Antarctica ice), bacteria that can survive in highly acidic environment, bacteria that can survive in highly alkaline environment, bacteria that can withstand high radiations, aerobic bacteria, anaerobic bacteria, autotrophic bacteria, heterotrophic bacteria, and so on… are also helpful in classifying the bacteria.īased on Morphology, DNA Sequencing, and Biochemistryīased on the morphology, DNA sequencing, conditions required and biochemistry, scientists have come up with the following classification with 28 different bacterial phyla:Įach phylum further corresponds to the number of species and genera of bacteria. Along with the shape and DNA sequence, other things such as their metabolic activities, conditions required for their growth, biochemical reactions (i.e., biochemistry as mentioned above), antigenic properties etc. if they are related to each other despite their different shapes. DNA sequencing helps in understanding the relationship between two types of bacteria i.e. Nowadays, along with the morphology, DNA sequencing is also used in order to classify bacteria. either Gram positive or Gram negative staining. Classification of Bacteriaīefore the invention of the DNA sequencing technique, bacteria were mainly classified based on their shapes – also known as morphology, biochemistry and staining – i.e. This article will give you the classification of these micro-organisms based on all these factors, as well as a few other factors. The classification of bacteria is based on many factors like morphology, DNA sequencing, requirement of oxygen and carbon-dioxide, staining methods, presence of flagellae, cell structure, etc. However, each of these types possess their own peculiar characteristics – which have evolved after separation from the original species. There are various groups of bacteria, which belong to the same family and have evolved from the same bacteria (ancestoral).

There are several different types of bacteria, and they are found everywhere and in all types of environment. They come in different shapes and sizes, and their sizes are measured in micrometer – which is a millionth part of a meter.

Bacteria (singular: bacterium) are single-celled organisms which can only be seen through a microscope.

Two types of bacteria shapes