Bacterial Cultivation Flashcards
What conditions are required for bacterial growth
Moisture, temperature, pH, Gas (O2), nutrients and ionic balance/salinity
What is a catabolic reaction
Energy releasing reaction
What is an anabolic reaction
Building energy into food
What are the 4 macronutrients bacteria need for growth
Proteins, lipids, carbohydrates and nucleic acids
What are the 4 key elements bacteria need for growth
Carbon, oxygen, nitrogen and phosphorus
What is ‘media’
The nutrition given
What are the two general types of media used
Chemically defined media and undefined complex media
What are the three main examples of undefined media
Tryptone, yeast extract and NaCl
How is media provided in the lab
Either in liquid broth or solid agar
What are the two things we can measure in bacterial growth
Population density and population number
What are the two things we can calculate in bacterial growth
Growth rate and generation time
How is population density measured
Measures light scattering by cells (used to assume PD)
What are the pros of measuring population density
-Simple and convenient
- non-destructive and can be done continuously
What are the cons of measuring population density
- low sensitivity (>10^6 cells per ml lower limit)
- not accurate as light can be absorbed by dead cells too (not viable cells)
How do we measure population number
Extrapolate from colony forming units (CFU) to give cell numbers in original culture
What are the pros of measuring population number
Only measures viable cells
What are the cons of measuring population number
-Underestimates for cells in chains or clusters
- laborious and slow (can’t do continuously)
Which phase of batch culture does growth become logarithmic
Exponential phase
What is the equation to determine final cell number
Final cell number (N)= Initial cell number (No) x 2^number of generations (n)
What is the equation for generation time
Generation time (g) = duration of exponential growth (t)/number of generations (n)
Why is generation time useful
- compares different bacterial species growing in same condition
- compares same bacterial species in different conditions
- can show whether data is statistically significant or not
What are extremophiles
Organisms that grow under harsh conditions
What are cardinal temperatures
Minimum, optimum and maximum temperatures an organism can survive at
Which species of bacteria has a min temp of 4 degrees an optimum of 39 and a maximum of around 48 degrees
Mesophiles
