What are the different ways of the classification of bacteria?
Posted April 19, 2023
Answer
Bacteria may be classified using many different classification systems.
- Based on the cell wall:
- Peptidoglycan cell wall – Gram-positive bacteria
- Lipopolysaccharide cell wall – Gram-negative bacteria
- Based on shape:
- Coccus – Unicellular, spherical shaped, remaining as a single cell or aggregating together in various configurations
- Bacillus - Rod-shaped or cylindrical, remaining singly or in pairs
- Spirilla or spirochete – Spiral with multiple curvatures in its structure and terminal flagella
- Vibrio - Comma-shaped or curved and represented by a single genus
- Based on mode of respiration:
- Aerobic – Break down glucose molecules completely in the presence of oxygen to yield energy
- Anaerobic – Break down glucose partially in the absence of oxygen to yield reduced energy
- Based on mode of nutrition:
- Phototrophs – Gain energy from light
- Autotrophs – Obtains carbon only from carbon dioxide to prepare its own food
- Heterotrophs – Source carbon from organic compounds
- Chemotrophs – Gain energy from chemical compounds
- Based on number of flagella:
- Atrichos – No flagella
- Monotrichous – One flagellum attached at one end of the cell
- Lophotrichous – Multiple flagella attached at one end of the cell
- Amphitrichous – Multiple flagella attached to both ends of the cell
- Peritrichous – Flagella evenly distributed around and covering the entire cell
- Based on optimum temperature for growth:
- Psychrophiles –15 °C or below
- Psychotrophs – 20°C to 30°C
- Mesophiles - 37°C
- Thermophiles – Above 45°C
- Hyperthermophiles – Above 80°C
- Based on optimum pH requirements for growth:
- Acidophiles – Acidic pH
- Alkaliphiles – Alkaline pH
- Neutrophiles – Neutral pH 6.5 to 7.5
Additional resources
Classification of Bacteria and Archaea: past, present and future
MycoLight™ Fluorimetric CTC Live Bacteria Quantification Kit