- 1. If a colorimeter or spectrometer
is available, measure the turbidity of
the culture
sample before testing it for enzyme activity. This will give an indication of the
growth of the yeast.
2. Before testing the culture samples for enzyme activity,
measure the concentration of
glucose
in each, using a glucose test strip.
3. Investigate the effect of growing S. diastaticus
on substrates other than starch. Does
it still produce glucoamylase
in these conditions?
Step
1. Set
up and inoculate the Bioreactor as described in the User Guide and the
accompanying notes.
Step
2. Use starch broth in the flask and
Saccharomyces diastaticus as the inoculum.
The yeast secretes an enzyme, glucoamylase, into the culture medium. This
breaks down the starch to glucose.
Step
3. Try to predict
what will happen to the
number of yeast cells during the fermentation
what will happen to the
enzyme concentration
what will happen to the glucose concentration
Enzyme assay
Step 1. Spin down the yeast cells, then take some of the cell- free supernatant
Step 2. Mix equal volumes of 1% starch solution and cellfree broth
Step 3. Incubate at 30oC, then test with a glucose test strip
Step 4. Record the glucose concentration, then put the used test strips into disinfectant
Step
5. Present your findings as a
graph
