Physiology of Bacteria Flashcards
The study of the function of bacterial processes and reactions with respect to the bacteria themselves
Bacterial Physiology
Concerns the life-supporting functions and processes of bacteria, which allow bacterial cells to grow and reproduce
Bacterial Physiology
refers to the number of cells, not the size of the cells
Microbial growth
Requirements for growth of a cell/bacteria
Physical
Chemical
The growth and death of a bacterial population in liquid media is influenced by the following factors
-Moisture
-pH
-Temperature
-Amount and quantity of food
-Waste products
What are the physical requirements in microbial growth
- Temperature
- Light
3.Moisture - Acid/Alkali (ph)
- Osmotic Pressure
- Macro/Micro elements
- Oxygen
Causes bacteria to cease to row but are not killed
Low temperature
Causes death of Bacteria
High Temperature
3 groups wherein bacteria can be divided depending on the temperature
- Psychrophilic (cold-loving)
- Mesophilic (Moderation-loving)
- Thermophilic(Heat-loving)
Grows best at optimum temperature of 10°-15 °C. (water
bacteria)
Psychrophilic or cold-loving bacteria
Thrives in extreme environments.
It can survive sub-zero temperatures, high pressure, low oxygen, and a nutrient-poor habitat
extremophile
Prefer optimum temperature of 20°- 37°C. (pathogenic bacteria)
Mesophilic or Moderation-loving bacteria
Bacteria that grow well at 50°-60°C. (soil bacteria)
Thermophilic or heat-loving bacteria
Influence of Temperature on Bacterial Activity
- Optimum growth temperature
- Minimum growth temperature
- Maximum growth temperature
- Thermal death point
- Thermal death time
The temperature at which the most rapid growth and multiplication of bacteria take place. (Mesophilic bacteria: 37°C)
Optimum growth temperature
The lowest temperature at which growth is possible. (Mesophilic bacteria: 15° - 20°C)
Minimum growth temperature
The highest temperature at which growth is possible. (Mesophilic bacteria: 40° - 55°C)
Maximum growth temperature
the lowest temperature at which microorganisms are killed by heat within a specified time, usually 10 minutes.
Thermal death point
length of time required to kill all bacteria in a given substance at a stated temperature (Pasteurization of milk for 30 minutes to a temperature of 60°-65° to render it free of disease germs.)
Thermal death time
- Majority of bacteria are it
- have no chlorophyll or photosynthetic pigment, and their growth is not aided by light
Chemosynthetic
Kills bacteria and they are also heated and dried
Exposure to sun (ultraviolet light)
Bacteria that trap the energy of sunlight in a manner similar to green plants
phototrophic autotrophs
bacteria that synthesize food by the using the energy obtained from inorganic compounds
Chemotrophic autotrophs
