Growth of Bacteria Flashcards
How do you isolate a single bacteria on a solid media?
Use:
- Sterile media
- Aseptic technique
- Flaming loops (to prevent contamination)
How can you measure bacterial growth in a culture
- Direct counting by microscope
- Colony counting
- Absorbance (a measurement of absorbance of liquid culture)
What is the growth rate
it is a measure of how rapidly bacteria grow in the exponential phase
Give some examples of environmental factors that affect bacteria growth
- pH
- Temperature
- Osmolarity
- Atmosphere
- Nutrients
How does pH affect bacteria growth
Depends on the individual type of bacteria to what is the optimum pH. Their enzymes are denatured at the wrong pH
How does temperature effect bacteria growth
Different bacteria have different optimum temperatures
growth rate increases up to a certain point then drops as enzymes are denatured
Define aerobic in terms of bacteria
Uses oxygen as a terminal electron accepter
Define anaerobic in terms of bacteria
Cannot use oxygen has to use a variety of other terminal electron acceptors
Define facultative anaerobe in terms of bacteria
can use oxygen as a terminal electron acceptor or switch to use other acceptors
What is a terminal electron acceptor?
is a compound that receives or accepts an electron at the end of the respiratory electron transport (or end of photosynthesis)
Define microaerophile in terms of bacteria
requires oxygen to survive, but requires environments containing lower levels of oxygen than that are present in the atmosphere.
How do bacteria get energy
They oxidise organic compounds in the immediate environment
How do you get rid of unwanted bacteria
Sterilisation
Washing
Disinfection
What is a minimal media
A basic salts based growth media often with a single carbon source
Describe a nutrient media
a medium with all the basic requirements for growth but without specific supplements
Describe an enriched media
Nutrient media with additional organism-specific supplements (e.g. blood agar)
Describe a selective media
A nutrient medium with the basic requirments for growth and added supplements that allows one bacterial type to grow more than another
Describe a indicator medium
a medium with indicators which react to specific bacteria
Describe a selective indicator medium
a combination of selective and indicator media
Describe a transport medium
a medium designed to protect the organisms in your sample on the way to the lab
