Classification On the basis Of shape

1. Cocci

Cocci are round or oval in shape. (singular coccus)

For example miningococci and gonococci.

cocci are further classified in to following groups

on the basis of their microscopic arrangement.

Diplococci: arranged in pairs

Streptococci: arranged in chains

Staphylococci: form grape like clusters.

2. Bacilli

Bacilli are rod shaped bacteria. Forexample E. coli,

Salmonela, C. Tatani. B. anthrax etc.

3.Spirochetes Spirochetes are spiral shaped they have flexible cell

wall.

for example, treponema, borrelia, laptospora etc.

4. Vibro Vibro are comma shaped, for example vibro cholera

and vibro vulnificus etc.

Classification On the basis Of Staining

1. Gram

Positive

Bacteria

Gram positive bacteria are those which hold the

crystal

violet dye after being washed with the alcohol. They

are

stained dark purple in color. They have this

Property because they contain higher quantity of

peptidoglycan in their cell wall

For example. Streptococci, Clostridium, Bacillus

anthrax etc.

2. Gram

Negative

Bacteria

Gram negative Bacteria lose the crystal violet dye

when

they are washed with alcohol. Then the are counter

stained

and give pink or red color in Gram staining technique.

For example E. coli, Salmonella Typhi. etc

3. Acid Fast

Bacilli.

Acid Fast bacilli are those which hold the dye even

after

being washed with an acid. These bacteria are not

stained

by gram staining technique. These are stained

Using special type of staining procedure called

Zeihl Nelson Staining technique

Classification On the basis Of Temperature

1.

Thermophiles

Thermophiles are those bacteira which grow

best in higher temperature. for example

Campylobacter jejuni which grows best at

42 degree centigrade.

2. Mesophiles

Mesophiles grow best at moderate temperature.

many

bacteria belong to this group

3.

Psychrophiles

Psychrophiles Grows best at lower temperature.

Classification On the basis Of Oxygen Requirement

1. Aerobes Aerobes are those bacteria which can grow only

in the presence of normal concentration of oxygenFor

example Mycobacterium Tuberculosis

2. Anaerobes An aerobes are those bacteria which can grow only in

absence of Oxygen for example bacteroides.

3. Facultative

Anerobes

These bacteria are capable of growing both in the

presence

and absence of Oxygen for example E. coli

4. Micro-aero

phillic

These bacteria require extremely low concenteration

of

Oxygen for their growth.

Classification On the basis Of Cell Wall

1. Thick Walled

Bacteria

These bacteria have thick cell wall for example

All gram positive and gram negative bacteria

2. Thin walled

Bacteria

these have thin flexible cell wall for example

spirochetes

3. Wall

less Bacteria e.g Mycoplasma

Classification On the basis Of Spore Formation

1. Spore

Forming

Rods

Aerobic: Bacillus Anthrax

Anerobic: Clostridium

2. Non Spore

Forming Rods

Non Filamentous: Corynebacterium

Filamentous: Listeria

Actinomyces

Nocardia