Bacteria are single-celled organisms, found in almost each and every type of environment. They are the oldest living organisms on earth. They are so small that they cannot be seen with the naked eye and have to be seen through a microscope. In fact, their size is measured in micro-meter (a millionth part of a meter). There are thousands of species of bacteria found in the world. They are commonly found in ground, water and other living organisms. However, we can classify these species into groups, depending upon a number of factors, like their shape, gram strain, etc.
It is interesting to note that while some kind of bacteria can be the cause of diseases and can harm humans and animals, there are some known for their benefits, often described as ‘friendly bacteria’. There are some types of bacteria, which can attack the plants and lead to diseases like leaf spot and fire blight. On the opposite side, some bacteria help in the production of the food that we eat and also aid the digestion of food. Some friendly bacteria also keep the soils fertile. In the following lines, we have provided a list of the different types of bacteria (microbes) found in the world.
Different Types of Bacteria
Classification on the Basis of Shapes
Bacteria are usually classified on the basis of their shapes. Broadly, they can be divided into:
- Rod-shaped bacteria (Bacilli)
- Sphere-shaped bacteria (Cocci)
- Spiral-shaped bacteria (Spirilla)
Classification on the Basis of Gram Strain
This classification is based on the results of Gram Staining Method, in which an agent is used to bind to the cell wall of the bacteria.
Classification on the Basis of Oxygen Requirement
This classification is based on the requirement of oxygen for the survival of the bacterium.
- Aerobic (Need Oxygen)
- Anaerobic (Do not need Oxygen)
Classification on the Basis of Growth and Reproduction
This classification is based on the growth and reproduction aspects of bacteria.
- Autotrophic Bacteria (Obtain carob and/or sugar from sunlight or chemical reactions)
- Heterotrophic Bacteria (Obtain carob and/or sugar from the environment)
Classification on the Basis of Phyla
This classification is based on the phyla, determined through morphology, DNA sequencing, conditions required and biochemistry.
Each phylum can be further related to a number of species and genera of bacteria. The classification of bacteria basically includes those bacteria which are found in diverse environments, such as sweet water, ocean (like in sulfur water spring bacteria) extreme cold (like bacteria found in the ice of Antarctica), highly acidic environment, and highly alkaline environment. Then, we have aerobic bacteria, anaerobic bacteria, autotrophic bacteria, heterotrophic bacteria, and bacteria that can endure high radiation. Each type of bacteria has its separate characteristics.