Unit 2 - KA 6: Environmental Corntrol of Microorganisms Flashcards
Give the three examples of microorganisms
Archaea
Bacteria
Some euakryotes (yeast)
Describe microorganisms’ purpose
Microorganisms use a wide variety of substrates for metabolisms and produce a range of products from their metabolic pathways.
What properties make microorganisms useful in industry?
Adaptability
Ease of cultivation
Speed of growth
What conditions are microorgansims grown in?
In a lab in either a solid medium (agar jelly) or a liquid medium (broth), containing essential nutrients in either petri dishes, flasks or within large fermenters for industrial processes.
what do microorganisms’ growth media require?
An energy source
Raw materials for biosynthesis
Describe types of energy sources that may be required.
Some microorganisms may need light energy for growth.
Most require a chemical substrate to provide energy.
Describe the need for raw materials for biosynthesis.
Some microbes can produce all the complex molecules required for biosynthesis.
Others require these to be supplied in the growth media.
Name the four phases of growth in microorganisms
Lag
Log/exponential
Stationary
Death
Describe the lag phase
No increse in number
Enzymes that control the metabolic rate are induced
Microorganisms adjust to the growth medium and show increased metabolic activity
Describe the log/exponential phase
This phase shows most growth due to the plentiful supply of nutrients
Exponential growth- population doubles with every cell division
Describe the stationary phase
During this phase the number of microbes being produced is equal to the number of cells dying.
Secondary metabolites such as antibodies are produced, allowing them to outcompete.
Describe the death phase
During this phase there is a lack of nutrients and a build up of toxic metabolites.
the number of cells dying exceeds production
Give reasons for the beginning of the stationary phase.
The depletion of nutrients.
the production of toxic metabolites.
Why are semi-logarithmic graphs used?
A semi-logarithmic graph allows the high numbers of microorganisms to be plotted on a graph accurately.
Describe Total and Viable cell count.
Total cell count includes dead cells.
Only living microorganisms are included in a viable cell count.
Viable cell counts will show a death phase where the number of viable cells is decreasing.
