Distribution of microorganism

Liebig's Law of the Minimum

Shelford's Law of Tolerance

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

oxygen concentration

aerobes
facultative anaerobes
aerotolerant anaerobes|
strict/obligate anaerobes
microaerophiles

water

as solvent

for cellular function, metabolism

carbon

-chemical building block for cells
-source of energy

nitrogen, phosphorus & sulfur

special growth factor

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

e.g. : Legionella pneumophila

trace elements

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

for function of enzyme or metabolism

not necessary to specifically provide

solute & water activity

hypotonic solution(low [osmotic])

hypertonic solution (high [osmotic])

quantity of water availability=water activity

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

pressure

land or surface of water -> pressure 1 atm

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

-barophilic
-piezophilic
-barotolerant
-eztreme barophiles

radiation

major source of radiation :sunlight

visible light, UV radiation, infrared rays and radio waves

most important criteria : intensity of light wavelenght duration

UV radiation damage :formation of thymine dimers

slight damage of UV is reversible - photoreactivation