Sunday 17 November 2019

Factors affecting the growth of microbes


Growth  An orderly increase in the quantity of all the cellular constituents.  The growth of microorganisms is influence...
Physicalfactorsinfluencingthegrowthofmicroorganisms Temperature pH Osmotic Pressure Hydrostatic Pressure Radiation

Temperature  Temperature is the most important factor that determines the rate of growth, multiplication, survival, and d...
Types of temperature Minimum growth temperature Optimum growth temperature Maximum growth temperature
1. Minimum growth temperature The lowest temperature at which organisms grow is the minimum growth temperature. 2. Optimum...
Classification of bacteria according to growth temperature

 Psychrophiles/cryophiles- 1. The term psychrophile was first used by S. Schmidt-Nelson. 2. Extremophilic organisms that ...

 Mesophiles- 1. Grows best in moderate temperature. 2. Temperature range: 20°C to 45°C. 3. Examples: Escherichia coli, St...
 Psychrotrophs- 1. Cold‐tolerant bacteria. 2. Have optimal and maximal growth temperatures above 15 and 20°C, respectivel...
 Thermophiles- 1. Derived from Greek word thermotita meaning heat and philia meaning love. 2. Heat-loving microorganisms....


 Hyperthermophiles- 1. Thrives in extremely hot environments. 2. Temperature range: 80°C to 113°C. 3. First discovered by...

 pH refers to negative logarithm of hydrogen ion concentration.  Microbial growth is strongly affected by the pH of the ...
Classification of bacteria according to pH
 Acidophiles- Grow between pH 0 and 5.5. Examples: Ferroplasma, Thiobacillus thioxidans, Sulfolobus acidocaldarius, etc. ...
Osmoticpressure(solutesandwateractivity)  Osmotic pressure is the minimum pressure which needs to be applied to a solutio...


Classification of bacteria according to osmotic pressure 1. Osmotolerant are those microorganisms which can grow at relati...

HydrostaticPressure  Force acting per unit area. Classification of bacteria on the basis of hydrostatic pressure  Baroto...




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