Different Types of Bacteria

Do you know that bacteria are omnipresent in our environment? However not all bacteria are dangerous and there are many different kinds of bacteria. Read on to learn about the various different types of bacteria.
| Friday, October 31, 2008
Bacteria are single celled organisms that are not visible to the naked eye and can be seen only through the microscope. They come in different sizes and different bacteria thrive in different environments. All kinds of bacteria ordinarily have a protective layer enclosing them and this is called as a cell wall. Some species of bacteria also have another slimy layer covering the cell wall and this makes some of the bacteria resistant to certain destructive chemicals. Bacteria are typically found everywhere and the air that we breathe is filled with many kinds of bacteria. However not all kinds of bacteria are harmful for the human body.

Microbiologists classify the bacteria as per their shape. So one can ordinarily have spherical bacteria, rod shaped bacteria and spiral shaped bacteria among other types. Pleomorphic bacteria are the type that assumes different shapes. In recent times DNA sequencing is used for classification of bacteria and this is helpful in understanding the relationship between different types of bacteria. Some other aspects that are also taken into consideration while classifying the various types of bacteria include the metabolic activities of the bacteria, the required conditions for their growth, antigenic properties, biochemical reactions, their reaction to Gram’s stain test etc. The bacteria in which the alcohol causes the Gram’s stain to be washed away are the gram negative bacteria whereas the bacteria where the alcohol makes the walls of the bacteria absorb the stain are the gram positive bacteria.

Following is a brief classification and description of the various bacteria types
  • Ascetic Acid: These are rod shaped, aerobic bacteria of the gram negative kind. They are extremely tolerant to acidic conditions and generate organic acids.
  • Coccoid: These are spherical is shape and sometimes are seen in strings or clusters. They are gram positive and resistant to drying and also in high salt conditions. They can be aerobic and anaerobic and the common species of this type of bacteria is staphylococcus which is found on the human skin. Some strains of these bacteria are associated with the toxic shock syndrome.
  • Endospore-fixing: They are normally rod shaped and can either be gram negative or then gram positive. They are extremely adaptable and have heat resistant spores and these can remain dormant for extended periods of time. They include anaerobic kind like clostridium and aerobic kind like bacillus.
  • Actinomycete: They are rather filamentous or rod shaped and are of the aerobic, gram positive kind. They are found in soils and are rather crucial for the development of many different plants. Many of the antibiotics produced find their source in actinomycete.
  • Gliding: These are rod shaped and are gram negative. They are mostly aerobic and glide easily on slimy secretions. They form colonies.
  • Coryneform: These are rod shaped bacteria that form club shapes or V shapes. They are aerobic and gram positive and are found in different habitats. They are extremely resistant to drying and common kinds include arthobacter.
  • Enteric: These bacteria are rod shaped and gram negative. These are primarily aerobic but can survive in certain anaerobic conditions. Escherichia coli, Shigella and Salmonella are the types included in this variety and these can create acids from glucose and nitrite from nitrate.
  • Mycoplasma: These are spherical in shape and aerobic but are capable of surviving in some anaerobic conditions. They do not have cell walls and are among the smallest of all bacteria types. They are named for their resemblance on a superficial level to the hyphae fungal.
  • Mycobacterium: These are pleomorphic bacteria that frequently branch and are rod shaped or spherical. These include the bacteria responsible for tuberculosis namely mycobacterium tuberculosis.
  • Propionic acid: They are rod shaped gram positive bacteria that are anaerobic. They result in fermentation in lactic acid.
  • Spirillum: These bacteria are spiral shaped and are aerobic and gram negative. They are responsible for typhus and these and agrobacterium are closely related.
  • Spirochete: They are spiral shaped anaerobic bacteria that are gram negative. They are found in moist environment. These include treponemapallidum and are responsible for syphilis.
  • Lactic acid: These are anaerobic, gram positive bacteria and include lactobacillus.
  • Sheathed: These are filamentous aerobic bacteria that are gram negative.
  • Nitrogen-fixing: They are aerobic, gram negative and rod shaped bacteria. These are responsible for conversion of nitrogen gas in atmosphere into ammonium within the soil and include Azotobacter.
  • Sulphate reducing: They are ordinarily rod shaped and many of them are anaerobic and gram negative. These include desulfovibrio and their presence is important within the marshes.
  • Psuedomonad: They are rod shaped and are gram negative and aerobic. These can ordinarily use around 100 various compounds for energy and carbon.
  • Sulfur oxidizing and iron oxidizing: They are ordinarily rod shaped and gram negative. Almost all bacteria in this type live in environments that are neutral.
  • Vibrio: These are comma shaped or rod shaped and are aerobic and gram negative. They commonly have a single flagellum and a common type of bacteria in this kind includes vibrio cholerae which is responsible for cholera.