Bacteria- kingdom Prokaryote


Bacteria- kingdom Prokaryote; Kingdom prokaryotes so-called kingdom Monera. It includes organisms with prokaryotic cells (does not contains a prominent nucleus and organelles membrane-bounded). So this kingdom includes Bacteria and cyanobacteria.


The smallest living organism that shows widely distribution and habitat. Mostly their occurrence is in hot springs, humid places, soil, milk, skin surface etc. but abundantly they are found in dead bodies of plants and animals also.

Classification of bacteria:

Biologists classify bacteria into two major categories:

  • Eubacteria
  • Archaeobacteria

Forms of Bacteria:

There are three types of bacteria according to shape:

  • Spherical (found in pairs, chains, cluster, tetrad, octet)
  • Examples are Streptococcus, Staphylococcus, Aureus
  • Straight (have straight or rod shape)
  • Examples are E.coli, Bacillus, Subtilis
  • Spiral (usually occur in a single form or in colonies)
  • Examples include Vibrio, Hyphomicrobium

There are some exceptions to above shapes, bacteria are also found in square, star,  spindle shape, lobe shape, trichome forming sheathed, filaments and stalked.

Mode of Nutrition:

Bacteria use two modes for their nourishment:

  • Autotrophic (includes Photosynthetic and Chemoautotrophic Bacteria)
  • Examples include green sulphur bacteria, nitrifying bacteria, purple non-sulphur bacteria
  • Heterotrophic (includes Heterotrophic bacteria)
  • Heterotrophic bacteria include Saprotroph and Parasitic Bacteria
  • Examples are soil bacteria and pathogenic bacteria

Reproduction In Bacteria:

Bacteria- kingdom Prokaryote; Bacteria reproduce in two different ways

  • Asexual Reproduction
  • Binary Fission
  • Sexual Reproduction
  • Conjugation
  • Transduction
  • Transformation

Importance of Bacteria:

  • Bacteria act as decomposers because they break down dead bodies of plants and animals by secreting enzymes
  • They also help in the emulsification (digestion of fats and lipids) in the large intestine of the human body
  • Some bacteria produce vitamin B, vitamin B12  and vitamin K for commercial purposes
  • Streptomycin, Terramycin, Aureomycin are some important antibiotics which are obtained from bacteria
  • A wide range of bacteria used in industry for manufacturing of many essential products acetic acid, acetone, lactic acid, butanol (alcohol) etc
  • Bacteria fix nitrogen, carbon and other nutrients for green plants and help them in the process of photosynthesis
  • Many dairy products like yoghurt, cheese, butter are produced by bacteria
  • They are very helpful in coffee and leather industries
  • In genetics studies, bacteria are very useful for example E.coli

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