BACTERIA, OCCURANCE OF BACTERIA, GENERAL CHARACTER OF BACTERIA, SIZE OF BACTERIA, TYPE OF SHAPE OF BACTERIA

Fig - Bacteria 

Bacteria (Gk. Bacterion = Small Rod)

• It is first time shown by Dutch Merchant and Antony Won Leeuwenhoek (1676) in the stored rain water and the tarar scrapt from teeth and term these 'animalcules'
• Linnaeus in 1758 termed these 'Verms'
• Ehrenberg in 1828 gives the term 'Bacteria'
• Bacteria is a Prokaryotic, Ucternicellular micro-organism of kingdom Monera.Some bacteria are also present as the multicellular form e.g.- Epulopscium fishelsoni.

Occurrence of Bacteria

• Bacteria generally shows ubiquitous in distribution i.e. it found in everywhere, wherever the organic substances are present.

Charecteristics of Bacteria 

• It is prokaryotic in nature i.e. don't have true nucleus.
• It is generally unicellular in nature but some bacteria are also present in the multicellular form.
• It shows all type of nutrition except phagotrophic nutrition (nutrition occur in human being).
• It shows locomotion through gliding, flexion or flagella.
• It reproduce asexually, generally by fission, budding, spore formation etc.
• Sexual reproduction doesn't occurs but gene recombination occurs.
• Photosynthetic bacteria have lack chlorophyll but instead of chlorophyll, bacteriochlorophylls are present which shows anoxygenic photosynthesis.

Size of Bacteria 

• The average size of unicellular bacteria is varies  between 1µm x 2µm - 1.5µm x 2.5µm.
• The smallest bacteria is Mycoplasma genetalium (size 0.1µm to 0.15µm)
• The largest unicellular bacteria is Thiomargarita namibiensis (size 100µm to 300µm)
• The size of multicellular bacteria varies approximately among   750µm e.g. Beggiotaa mirubilis, Epulopscium fishelsoni (size 600µm x 80µm).
• Epulopscium fishelsoni is found in the intestine of brown sturgeon fish.

Shape of Bacteria

• Cohn in 1972 gives about the shape of Bacteria and says bacteria basically are of following types

1. Bacillus 
2. Coccus 
3. Spirillum 
4. Vibreo
5. Spirichaete
6. Mycelia bacteria 
7. Stalked bacteria 
8. Budding bacteria 

Bacillus ( L. Bacillus = Small rod)

• Bacteria having Rod-like, Cigar-like and cylindrical in shape.
• It is also subdivided into four types as 

1. Single bacillus = single rod shaped
2. Diplobacillus = paired 
3. Palisade bacillus = stalked like 
4. Strepto bacillus = chain like

Fig - All types of  bacillus bacteria

Coccus (Gk. kokkos = berry)

• Bacteria which are spherical or oval in shape
• It is also of four types named as

1. Mono coccus = single 
2. Diplo coccus = paired
3. Tetra coccus = group of four cells 
4. Sarchina = 3D cube shaped 
5. Strepto coccus = chained 
6. Staphilo coccus = cluster of grapes

Fig - All types of coccus bacteria

Spirillum (L. Spirillum = small coil)

Fig - Spirillum, Spirochaete, vibrio, Stalked 

• The bacteria which is cylindrical with two to more coiled in shape. i.e. no axial-filamentous structure.

Vibreo (L. Vibrare = quiver)

• The bacteria which are spiral or comma in shape.

Spirochaete (Gk. Speira = coil, chaite= hair)

• The bacteria which are cylindrical with more coiled structure and also having axial filaments.

Mycelia bacteria 

Fig - Mycelial, Budding

• The bacteria which are branched and filamentous in structure.

Stalked bacteria 

• The bacteria having stalk at one end.

Budding bacteria

• The bacteria which are one or more but attached to each other.

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