Environmental control of metabolism - learning outcomes/ questions Flashcards
Micro-organisms are what?
archaea, bacteria and some species of eukaryotes.
Micro-organisms use a wide variety of substrates for what and produce a range of products from their what?
Micro-organisms use a wide variety of substrates for metabolism and produce a range of products from their metabolic pathways.
Why are Micro-organisms used?
Micro-organisms are used because of their adaptability, ease of cultivation and speed of growth.
When culturing micro-organisms, their growth what require raw materials for what as well as what type of source?
When culturing micro-organisms, their growth media require raw materials for biosynthesis as well as an energy source.
An energy source is derived either from what?
An energy source is derived either from chemical substrates or from light in photosynthetic micro-organisms.
Examples of Culture conditions
Culture conditions: sterility; control of temperature, oxygen levels and pH.
Sterile conditions in fermenters reduce what with desired micro-organisms for nutrients and reduce the risk of what?
Sterile conditions in fermenters reduce competition with desired micro-organisms for nutrients and reduce the risk of spoilage of the product.
Name the phases
Phases — lag, log/exponential, stationary and death.
The lag phase is what?
The lag phase is where enzymes are induced to metabolise substrates.
The log phase contains what?
The log/exponential phase contains the most rapid growth of micro-organisms due to plentiful nutrients.
Why does the stationary phase occur?
The stationary phase occurs due to the nutrients in the culture media becoming depleted and the production of toxic metabolites.
What else is produced during the stationary phase?
Secondary metabolites, such as antibiotics, are also produced during the stationary phase.
In the wild these secondary metabolites confer an ecological advantage by what?
In the wild these secondary metabolites confer an ecological advantage by allowing the micro-organisms which produce them to outcompete other micro-organisms.
Why does the death phase occur?
The death phase occurs due to the toxic accumulation of metabolites or the lack of nutrients in the culture.
Viable cell counts involve counting only what?
Viable cell counts involve counting only the living micro-organisms whereas total cell counts involve counting viable and dead cells.
