Bacterial physiology Flashcards
What is the process by which bacteria replicate asexually?
Binary fission
Binary fission involves a single bacterium dividing to produce two identical daughter cells.
How do bacterial populations grow with each replication round?
They double
Each round of replication leads to a doubling of the bacterial population.
What is the generation time for E. coli?
What about M. bovis?
E. coli = every 20 minutes
M. bovis = every 20-24 hours
E. coli has a rapid generation time compared to other bacteria.
What are the minimum nutritional requirements for bacteria?
- Water
- Carbon source
- Nitrogen source
- Inorganic salts
These basic nutrients are essential for bacterial growth.
Define autotrophs in the context of bacteria.
Bacteria that synthesize their own organic compounds
Autotrophs are typically non-pathogenic.
What are heterotrophs?
Bacteria that cannot synthesize their own organic compounds
Some heterotrophs, like Salmonella spp. and Campylobacter spp., can be pathogenic.
What is the purpose of isolation in bacterial culture?
Identification and determination of antibiotic resistance profiles
Isolation is crucial in clinical settings to understand bacterial pathogens.
What type of media is used to cultivate bacteria in the laboratory?
Liquid media and solid media (agar)
Different media types are used based on the bacterial species being cultured.
How is antibiotic resistance tested in clinical isolates?
- Bacteria spread on a plate
- Antibiotic-soaked paper disks placed on top
- Growth is observed for clearance zones
The presence or absence of growth around the disks indicates sensitivity or resistance.
At what temperature are clinical isolates typically cultured?
37 °C
This temperature is optimal for many pathogenic bacteria, including E. coli.
List the temperature classifications of bacteria.
- Thermophiles: 50-80°C
- Mesophiles: 20-45°C
- Psychotrophs: 4-25°C
- Psychrophiles: 0-15°C
These classifications are based on the optimal growth temperatures of different bacterial species.
What is the optimal growth range for Listeria monocytogenes?
30-37°C
Listeria monocytogenes can also grow between 1-45°C.
What pH level do clinical isolates typically require for culture?
Neutral pH
Most bacteria thrive in a neutral pH environment.
What are the three types of organisms based on pH preference?
- Neutrophilic organisms
- Acidophilic organisms
- Alkalophilic organisms
These classifications indicate the pH range in which different bacteria can thrive.
What are the four stages of the bacterial growth curve?
- Lag
- Log
- Stationary
- Decline
Each stage represents a different phase of bacterial growth and activity.
What occurs during the lag phase of bacterial growth?
Bacteria increase in size, small numbers doubling
This phase is marked by metabolic activity but no significant cell division.
What is characterized by exponential increase in bacterial numbers?
Log phase
During this phase, bacteria actively divide and numbers increase rapidly.
What happens during the stationary phase of bacterial growth?
Bacterial division ceases due to nutrient depletion and toxic buildup
This phase is marked by a balance between cell division and cell death.
What is the significance of understanding bacterial physiology?
- Identification of bacteria
- Understanding nutritional requirements
- Control of clinically relevant bacteria
Knowledge of bacterial physiology is crucial for clinical and environmental applications.
