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Facts about Bacteria: Its Types and Characteristics

Updated on May 30, 2014
Kinds of bacteria
Kinds of bacteria | Source

Bacteria are single-celled organism that belongs to Kingdom Monera that is only visible through the use of a microscope. They can live in colonies, but some can live individually, they live all around us and within us. The air we breathe can be filled with bacteria and even in outer space they can enter through the spacecraft. Bacteria can live in the depth of the sea, in the hottest continents and even in the coldest regions on earth. They are everywhere, in the soil, in our food, on animals and plants, and even in human. The study of bacteria called bacteriology, a branch of microbiology.

Bacteria have three types according to shapes of the cell. Their rigid cell wall allows them to retain its shape:

  1. Round bacteria (cocci)
  2. Rod-shape bacteria (bacilli)
  3. Spiral bacteria (spirilli)

Scientist measure bacteria in units called “micrometers” (µm) because it is so small. Each micrometer is equal to a millionth of a meter (0.0000001 m or about 0.000039 in) and an average bacterium is only one micrometer long. So it is possible that thousands of bacteria would fit in a small dot of a pen.

Bacteria are totally different plant and animal cells in a way that they lack a true nucleus that carries genetic materials in the form of deoxyribonucleic acid (DNA) although they have their own DNA type that floats in a loop within the cell that is surrounded by tough but a resilient protective shell.

Archaebacteria and Eubacteria

The bacteria are known to be the earliest primitive organism from which all other forms of life may have evolved. It was recorded that the oldest known organism was dated some 3.5 billion years ago. They say that Monerans were only living inhabitants of the earth for at least two billion years before other forms of life evolved.

Biologist has also classified all life forms into two categories:

  • Prokaryotes – simple unicellular organism like bacteria, they lack true nucleus. The name comes from the Greek word “Prokaryote” which means “before nucleus”
  • Eukaryotes - complex organism whose cells have nucleus. The name comes from the Greek word “true nucleus”

Ancestral primitive bacterium has two major groups:

1. Archaebacteria –live in the most extreme habitats that were once considered inhospitable to life. They are group of one-celled organism that does not require sunlight and oxygen in order to live. Some archaebacteria are:

  • Anaerobic methanogens live in oxygen-deprived swamps
  • Halophiles live in saltwater
  • Thermoacidophiles live in very hot and acidic sulfur springs

2. Eubacteria- Most of them are disease-causing bacteria, but some are harmless and some can also benefit. They can be found in soil, air and water. They are also beneficial for some bacteria can produce antibiotics for medicine.

Some Eubacteria

Some eubacteria have proven to be ecological, economical and medicinal important. Some eubacteria includes:

  1. Bacteria of decay or decomposing bacteria
  2. Nitrogen-fixing bacteria
  3. Disease-causing bacteria or pathogenic bacteria
  4. Photosynthesis bacteria such as cynobacteria

Anaerobic bacteria are one of the interesting groups of eubacteria for it can live without the aid of air. This group is exemplified by bacteria in septic tanks.

Nitrogen-fixing bacteria are groups of bacteria that can make use of nitrogen in air. Except blue-green algae, other living things don’t have this type of capability. We all know that our atmosphere is composed of 78% nitrogen gas, yet plants cannot use even a single atom of that nitrogen for making protein but nitrogen-fixing bacteria can. This type of bacteria lives in the nodules on the roots of leguminous plants such as:

  • Peanut
  • Soybeans
  • Mongo
  • Weed (Mimosa pudica) or “makahiya”

Green-manuring enables farmers to improve nitrogen-content of the soil by planting leguminous plants that was stated earlier.


Photosynthetic bacteria are groups of chlorophyll-bearing species that can use energy from the sun for making food. This type of bacteria can perform photosynthesis. One good example of this is Cynobacteria which has 1500 species on record.

  • Oscillatoria – a very common cynobacteria. It is a multicellular organism that is filamentous because of the cells in the filaments is independent of the others. It was named in a way that filaments sway/oscillates in water.

Cyanobacterium | Source

Cynobacteria are also believed to be the earliest photosynthetic organism that produces oxygen in the primitive atmosphere of the earth. Cynobacteria have mucus-like/gelatinous cover that protects them and allow them to withstand the harsh condition of the primitive earth.

They store food in the form of a carbohydrate known as cyanophycean starch. Cynobacteria cell wall consists of cellulose and pectin. Cyanobacteria can survive in diverse habitats such as in rocks, walls, on land and even under water. Below are some of the most remarkable characteristics of :

  1. Cyanobacteria can withstand extreme environmental conditions because of their gelatinous sheath. Some species can live in cold places in Polar Regions; and some species can stand the extreme temperature of deserts and hot springs. Some species can also stand the high salt content of salt lakes.
  2. Oscillatoria a common type of cynobacteria can move in water.
  3. Nostoc and Anabaena have the capability to fix nitrogen from the air. Anabaena reveals a symbiotic relationship with a water-fern “Azolla” and together from Anabaena-Azolla complex. Nostoc and Azolla-Anabaena complex is being grown in rice fields and other agricultural crops to supplement the nitrogen supply acquired from the soil.

References ; Science and Technology by Lilia M. Rabago Ph. D , Crescensia C. Joaquin Ph.D, Catherine B. Lagunzad , PH. D, Encarta

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    • KenDeanAgudo profile image

      Kenneth C Agudo 4 years ago from Tiwi, Philippines

      hello sheilamyers :)

      Thank you for the read again. I just love biology and it was my favorite subject

    • profile image

      sheilamyers 4 years ago

      Yet another awesome hub! It's truly amazing to think about how these organisms are found everywhere yet we can't see them with the naked eye.