What drew me towards becoming a microbiologist was the world of the unseen organisms. There are millions and billions of these microscopic organisms around and within us. For a common man, there may not be much difference between bacteria vs virus. Bacteria are unicellular microorganism that come in different shapes. There are different kinds of bacteria, beneficial bacteria as well as pathogenic bacteria. The beneficial bacteria to humans is helpful in many ways. They help in fermentation of food and drinks, making antibiotics, killing pests, even digestion of food. The pathogenic bacteria on the other hand are the main reason for diseases caused by bacteria. To be able to differentiate between the helpful and harmful bacteria, scientists have come up with a scientific classification of bacteria. In the following paragraph, we shall see the biological classification of bacteria flowchart, that will help you learn all about the different bacteria.

Classification of Bacteria of Medical Importance

The classification of bacteria helps in identification of organisms according to groups. These groups contain organisms that share common characteristics and traits from other organism in a different group. The classification of bacteria of medical importance has been carried out according to the ‘Gram reaction’ all these years. Gram reaction is a medical staining test that is named after Christian Gram who came up with the process in 1884. He found out that the organisms have the ability to retain the crystal violet iodine complex after treating them with organic solvents like alcohol and acetone.

The organisms that are gram positive retain the stain color and look purple or blue black under bright field microbiology. Those who cannot retain the dye complex, need to be stained with a counter stain like carbol fuchsin and are called Gram-negative bacteria. Along with the Gram reaction, scientists also use the shape of bacteria to classify them. There are different types of bacteria shapes like: cocci (round), bacilli (stick or rod shaped), or spiral shaped. The following table covers the biological classification of bacteria according to their shape.

Scientific Classification of Bacteria Based on Bergy’s Manual

The Bergy’s Manual of Systematic Bacteriology is like the Holy Testament for us microbiologist. This manual is the guiding light for microbiologist to identify bacterial species and understanding their characteristics. This manual for first published by David Hendricks Bergy in 1923 and helped in classification of bacteria based on their structure and functional characteristics.
Classification of Bacteria Flowchart

The classification of bacteria is incomplete for a microbiologist till he/she cannot place each and every bacteria in their specific groups. The following is a classification of bacteria flowchart that contains names of most of the bacterial species under the specific groups according to their Gram reaction and specific group.

Classification of Bacteria of Medical Importance that give Gram Positive Reaction
This classification was carried out in 1984 and places the cocci, endospore-forming and nonsporing rods, mycobacteria, nonfilamentous actinomycetes under this group. Read the rest of this entry »