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10 Cards in this Set

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What are the differences in nutrient availablities between batch and continuous culture growth?
Batch Cultures- conditions remain constant only for a short time during early exponential growth. At later stages when the cell # is high. The composition of the medium will change dramatically

Continuous Growth- cells in constant environment for long periods of time. In the flow system therre is a constant flow of nutrients, they are added to a vessel while spent culture medium is removed at the same rate once at eq the cell # and nutrient status will remain constant and system is in steady state.
How can an experimenter vary the cell density in a chemostat experiment while keeping the growth rate constant? Can this type of experiment be done under batch culture growth conditions?
At a fixed dilution rate an increase in the nutrient level will result in an increase in the cell density while leaving the growth rate unchanged.
Why does the growth rate vary with growth substrate concentration in a manner similar to the enzyme substrate relationship?
Ks is the substrate affinity constant (similar to the Km of an enzyme) and is equal to the concentration of growth substrate at which there is half a maximal growth rate, the term Umax is the maxium growth rate
What are the four environmental factors that affect microbial growth?
1. Temperature
2. pH
3. Water availability
4. Oxygen
What molecular events are occuring that affect growth at the 3 cardinal temperatures?
1. Minimum- membrane gelling, transport processes so slow that growth cannot occur

2. Optimum- Enzymatic rxns occuring at maximal possible rates (on climb rxns occuring at increasingly rapid rates)

3. Maximum- Protein denaturation, collapse of the CM and thermal lysis
Why is there a sharp decrease in growth rate above the optimal growth temperature for most microbes?
Protein denaturation collapse of CM, thermal lysis
psychrophiles
low growth temperature optima
mesophiles
midrange growth temperature optima
thermophile
high growth temperature optima
hyper thermophile
very high growth temp optima