What happens to microorganisms when they die?

M2: living conditions of microorganisms

  Conditions for
optimal growth Conditions applicable to
Inhibit growth or lead to cell death 1. Nutrients All microorganisms need food, the following are particularly important:
Carbohydrates, protein and minerals. Nutritional deficiency 2. Oxygen A distinction is made based on their oxygen consumption:
Obligatory aerobes need O 2 .
Obligatory anaerobes only live without O 2 .
Facultative anaerobes live with and without O 2 . Depending on the bacterial group, the bacteria can be killed by adding or removing oxygen. 3. water All microorganisms need water to live. As a rule, the greater the water supply, the better the growth. A measure of the water available to the MO is that a w -Value . (= activity of water, available water) Sugar and salts bind water so that microorganisms cannot use it for growth -> high sugar or salt contents reduce the a w Value and inhibit MO growth. 4. Temperature According to their optimal growth temperatures, one differentiates between three groups of MO:
Psychrotrophes (cold-loving),
Mesophiles (love medium temperatures) and Thermophiles (warmth-loving).
Most microorganisms live at temperatures between
10 ° C and 50 ° C Very low temperatures prevent reproduction the MO.
High temperatures kill
Complete kill:
Heat for 20 minutes at 121 ° C = sterilization 5. pH In order for their metabolism to function, MOs need a certain pH value in their environment
z. B. Lactic acid bacteria -> pH 4 - 6, intestinal bacteria -> pH 7 - 9. Microorganisms cannot live at very high or very low pH values.
Additions of acids or bases inhibit MO.