Bacteria are single-celled organisms found in all environmental conditions. They are classified based on their shapes, sizes, cell structure, cell components, and metabolism. Scientifically, bacteria are classified into various phyla. Phyla are the scientific classifications of organisms.
Classification based on shapes
Before the DNA techniques were used for classification, the bacteria were classified on their shapes. The rod shaped bacteria are termed as Bacilli. Cocci are the sphere shaped bacteria and the spiral shaped ones are termed spirilla. Bacteria often have irregular shapes that do not fall under these three specific shape categories.
Aerobic and Anaerobic Classification
This classification is based on the need of oxygen for the growth and survival of the bacteria. Those bacteria that require oxygen to survive in the environment are termed aerobic bacteria and the ones that do not require oxygen are anaerobic bacteria. Some anaerobic bacteria might die in the presence of oxygen.
Classification based on Gram stain
The thick walls of the membrane in Gram-positive bacteria stain purple while the thin walls membranes of the Gram-negative bacteria are pink.
Autotrophic and heterotrophic classification
This type of classification is based on the reproduction and growth of the bacteria. Autotrophic bacteria require carbon and process sugar from carbon dioxide by using sunlight. Other autotrophic bacteria require chemical reactions for their growth. Heterotrophic bacteria get the sugar and carbon from the living organisms and cells in which they are present.
Phyla classification
In this type of classification, the bacteria are categorized under 15 different phyla. The bacteria under this classification are categorized based on DNA sequencing. Every phylum includes the bacteria’s genera and species. Aerobic and anaerobic bacteria, bacteria surviving in acidic environment and alkaline environment, bacteria surviving in extreme hot temperature such as in sulfur springs and the ones in extreme cold temperature such as in Antarctica, the ones that live in sweet water and in ocean water are all covered under each phylum.
Bacteria can be classified based on their healthy and harmful attributes towards other living organisms.
