Detailed Classification Of Bacteria - Microbiology

Classification On the basis Of Shape
1. Cocci	Cocci are round or oval in shape. (singular coccus)  For example meningococci and gonococci. cocci are further classified into the 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. For example E. coli, Salmonella, C. Tatani. B. anthrax etc.
3.Spirochetes	Spirochetes are spiral shaped they have a flexible cell wall.  for example, Treponema, Borrelia, leptospira etc.
4. Vibro	Vibro are comma-shaped, for example, Vibrio 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 colour. They have this Property because they contain a 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 they are counterstained and give a pink or red colour in the 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 acid. These bacteria are not stained by gram staining technique. These are stained  Using a special type of staining procedure called  Zeihl Nelson Staining technique
Classification On the basis Of Temperature
1. Thermophiles	Thermophiles are those bacteria 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 a lower temperature.
Classification On the basis Of Oxygen Requirement
1. Aerobes	Aerobes are those bacteria which can grow only in the presence of a normal concentration of oxygen For example Mycobacterium Tuberculosis
2. Anaerobes	Anaerobes are those bacteria which can grow only in the absence of Oxygen, for example, Bacteroides.
3. Facultative      Anaerobes	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 an extremely low concentration 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 Anaerobic: Clostridium
2. Non-Spore  Forming Rods	Non-Filamentous: Corynebacterium Filamentous:          Listeria                             Actinomyces                             Nocardia