this ppt describes about the various size ,shape and arrangement of bacteria with examples and pictures.

1. BACTERIAL CELL
BY-ALPANA DAVE

2. HISTORY
◦ The word bacterium (Gk. Bakterion = little rod)
◦ Originally applied for rod shaped organism.
◦ Which belongs to the lowest order of the plant life or "microscopic unicellular
plants without chlorophyll that reproduce by fission".
◦ Antony Von Leeuwenhoek discovered bacteria, named them as "tiny animalcules".
◦ He is called as "Father of Bacteriology".
◦ Ehrenberg (1829) coined the term bacteria for these microorganism.

3. Size of bacteria
◦ Great variation in size of bacteria.
◦ On an average each cell of bacterium measures 1.25 - 2 µm in diameter and 2-10
µm in length.
◦ The smallest rod shaped eubacterium is Dialister pneumosintes which measure
in between 0.15- 0.3 µm in size.
◦ The biggest bacteria Beggiatoa mirabilis is about 16-45µ in diameter and 80µ
in length.

4. ◦ Escherichia coli is a rod of about average size, 1.1 to 1.5 μm wide by 2.0 to 6.0 μm
long.
◦ Mycoplasma------about 0.3 μm in diameter.
◦ Nanobacteria and nanoarchaea ----- around 0.2 μm to less than 0.05 μm in diameter.
◦ Spirochetes----can reach 500 μm in length.
◦ Photosynthetic bacterium Oscillatoria, which is about 7 μm in diameter (the same
diameter as a red blood cell).

5. SHAPE & ARRANGEMENT
◦ Endless variety in terms of morphology.
◦ Usually three conventional shapes.
◦ Initial classification of bacteria was based on their shapes but now it is not used.
The various shapes are as follows:
◦ (1) Ellipsoidal/Spherical/Cocci –
◦ simplest form of bacteria, appears like a minute sphere (0.5~ - 1.25~ in diameter)
◦ they lack flagella.
◦ On the basis of arrangements cocci are further classified as follows:
◦ 1. Micrococci: When a bacterium appears singly e.g. Micrococcus agitis, M. aureus.

6. 2. Diplococcus: remains in pairs, cells divide in one plane.
e.g. Diplococcus pneumoniae.
◦ 3. Streptococci: remain attached to form
rows or chains and cells divides in one planes.
e.g. Streptocoocus lactis

7. 4. Tetracoccus: divides in two planes and
remains in group of four, forming square.
e.g. Neisseria and Micrococcus tetrogenus.
◦ 5. Sarcinae: when it divides in three planes
and form cuboidal like structure.
e.g. Sarcillae lutea

8. ◦ 6. Staphylococcus: formed by division in many planes ,
arranged randomly in a cluster like bunches of grapes
e.g. Staphylococcus aureus

10. ◦ (2) Rod Shaped Bacteria or Bacillus
◦ The word bacillus originated from greek word, bacillii means rod or stick.
◦ There ends are rounded flat or pointed.
◦ There size ranges from 0.5-1.2~ in diameter and 3- 7~ in length.
◦ They may be flagellated or non-flagellated.
◦ Most of the bacteria causing disease in plants belongs to bacilli category.

11. ◦ They may be of following types:
◦ (i) Monobacillus: When they arrange singly.
◦ (ii) Diplobacillus: When they are present in a group of two, appears in pairs after
division e.g. Diplobacillus pneumoniae
◦ (iii) Streptobacillus : When they appear in chains e.g. Bacillus tuberculosis.
◦ (iv) Palisade: Very rarely the bacillus arrange in a palisade arrangement

14. (3) Spiral or Helical
greek word; spira means coiled.
A single spirillum has more than one turn of helix.
Generally they are found as free living, unicellular entity.
There size ranges from 10-50~ in length and 0.5 - 3~ in diameter.
They are flagellated e.g. Spirillum minus, S. volutans.

15. ◦ (4) Vibrio or Coma
◦ The bacteria of this group are like 'coma or small curved rod.
◦ They bear flagella at their end.
◦ Their size ranges from 1.5-l.7µm in diameter and upto 10µm in length e.g. Vibrio
cholarae.

16. ◦ (5) Spirochaete
◦ These bacteria appears like a cork screw and atrichous.
◦ Their length is more as compared to their diameter.
◦ Their body is more flexible.

17. ◦ (6) Filamentous
◦ These type of bacteria are generally found in sewage water
and the effluent of sugar industry.
◦ e.g. Sphaerotilus natalls.
◦ Basically they are rod shaped bacilli which grow in an elongated
chain and are covered by a tubular envelope.
◦ Ferrous containing water generally contain filamentous bacteria
◦ e.g. Leptothrix, Cladothrix, Nocardia and Beggiatoa.

18. 7. ROSETTE
◦ Bacillus arranged in a rosette
◦ attached by stalks to a substrate.
◦ Caulobacter

19. 8. Star-shaped bacteria
e.g. Stella
9. Square-shaped
e.g. Haloarcula,
a salt-loving member of the Archaea.

20. ◦ 10. Pleomorphic
◦ Many bacteria change their shape and structure with the change in environmental
conditions.
◦ These bacteria which are found in various forms are known as pleomorphic bacteria
◦ e.g. Acetobacter.