distribution of microorganism

Plus de détails

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Distribution of microorganism

Physical factors

radiation

slight damage of UV is reversible - photoreactivation

UV radiation damage :formation of thymine dimers

most important criteria : intensity of light wavelenght duration

visible light, UV radiation, infrared rays and radio waves

major source of radiation :sunlight

pressure

-barophilic -piezophilic -barotolerant -eztreme barophiles

deep sea ->600-1,100 atm -> barotolerant inhibit chemical rxn

land or surface of water -> pressure 1 atm

temperature

1)psychrophiles ->opt : -5-10°C 2)psychrotrophs ->opt : 20-30°C 3)mesophiles ->opt : 20-45°C 4)thermophiles ->opt : 45-65°C 5)hyperthermophiles ->opt : 90-100°C

solute & water activity

quantity of water availability=water activity

hypertonic solution (high [osmotic])

hypotonic solution(low [osmotic])

Chemical factors

trace elements

not necessary to specifically provide

for function of enzyme or metabolism

e.g : Fe, Mn, Mg, Cu, Zn

special growth factor

e.g. : Legionella pneumophila

-specific nutrient eg. amino acid,/vitamin in low concentration -absence : cannot grow

nitrogen, phosphorus & sulfur

carbon

-chemical building block for cells -source of energy

water

for cellular function, metabolism

as solvent

oxygen concentration

aerobes facultative anaerobes aerotolerant anaerobes| strict/obligate anaerobes microaerophiles

pH

acidophiles : optima pH 0 to 5.5 neutrophiles : optima pH 5.5 and 8.0 alkalophiles : optima pH 8.5 to 11.5 extreme alkalophiles : optima above pH 10

Growth limitation by environmental factors

Shelford's Law of Tolerance

Liebig's Law of the Minimum