Environmental Control of Metabolism Flashcards
What is microbe metabolism?
Use wide range of substrates for metabolism.
Produce wide range of products from their metabolic pathways.
Why are micro-organisms used?
Because of their adaptability, ease of cultivation and speed of growth.
What are the culture conditions?
Sterility
Temperature
Oxygen concentration
pH
Sterility
Prevents contamination from other microbes.
Controlled by a filter.
Temperature
Maintains enzymes at optimum temperatures.
Controlled by probes and monitored by thermostat and water jacket.
Oxygen concentration
For aerobic respiration.
Controlled by aeration by paddles.
pH
Maintains enzymes at their optimum pH.
Controlled by the addition of buffers (or adding acid/alkali)
What is a fermenter?
Sterile conditions in fermenters reduce competition with desired micro-organisms for nutrients and reduce the risk of spoilage of the product.
What are the stages of microbe growth?
Lag phase
Exponential (log) growth phase
Stationary phase
Death phase
What happens at the lag phase?
Enzymes are being induced to metabolic substrates.
No cell division.
What happens at the exponential (log) growth phase?
Cell division is very high (most rapid growth) due to plentiful nutrients.
What happens at the stationary phase?
Occurs due to the nutrients in the culture media becoming depleted and the production of toxic metabolites.
Secondary metabolites are also produced, such as antibiotics.
In the wild these metabolites confer an ecological advantage by allowing the micro-organisms which produce them to outcompete other micro-organisms.
What happens at the death phase?
Nutrients/oxygen are used up.
No cell division.
Toxic accumulation of metabolites.
