Bacterial Growth Flashcards
How do bacterial cells divide?
Binary fission
What factors is bacterial growth limited by?
Space Temperature Toxic products Nutrient availability Competitors pH
What are the phases of bacterial growth?
Lag
Exponential
Stationary
Death
In which phase are secondary metabolites produced?
Stationary phase
Characteristics of the lag phase?
Slow growth
It is the time required to start up cell functions and establish the cell components that are required for growth
Characteristics of the exponential phase?
Rapid exponential growth, cells are growing at the maximum capacity
Excess nutrients are available
Growth is modified due to toxic chemicals being released
Characteristics of the stationary phase?
Numbers remain stable- some are growing, dying, or in stasis
Characteristics of the death phase?
Population decreases in size, death rate is higher that growth rate
Why do we measure bacterial growth?
To assess if antibiotics work
To compare growth rates between species
To quantify bacteria within a sample
How do we measure bacteria growth?
Directly
- counting via a microscope (red= dead, green= alive)
- plate counts
- flow cytometer
Indirectly
- estimation of numbers
- measuring respiration
What are the three methods of growing bacteria?
Using a broth (liquid media), agar (solid media) or a sloppy agar (semi-solid media)
What are the characteristics used to identify bacteria?
Colour, size, shape, smell, effect on the media
What is the name of a simple stain?
Methylene blue
Name 3 types of stain
Simple, negative, fluorescent
Outline the method of gram staining
Slide fixation, use of crystal violet stain, use of Lysol’s iodine, decolorisation through the use of alcohol (Gram Positive bacteria will retain colour), staining with Safranin (GP= purple, GN= pink)
