Advance preparation

Day 1

1. Set up and autoclave the NCBE Bioreactor as described in the User Guide, using 450 ml of
    starch yeast broth. After autoclaving, allow the vessel to cool, and attach sterile syringes
    etc. as instructed in ther Bioreactor manual.

2. Prepare an inoculum of Saccharomyces diastaticus in a McCartney bottle containing 20
    ml of starch yeast broth. Incubate at 28-30 ^oC.
 

Day 2

3. Place the Bioreactor in a water bath at 28^oC. Allow the broth inside to warm to this
    temperature, then inoculate the Bioreactor using the culture prepared in (2) above.
 

Running the Bioreactor

4. Bubble air through the culture medium to ensure that the conditions within remain aerobic. 
    Add antifoam as required to prevent undue frothing. Take care to ensure that the air
    filters do not become blocked with liquid.
 

Monitoring starch breakdown

5. Take small samples of broth from the Bioreactor at regular intervals, using the method
    described in the Bioreactor manual.

6. Put the sample into a centrifuge tube, cover with Cling film to prevent the formation and
    escape of aerosols. Spin down the yeast cells in a properly-balanced centrifuge. Take some
    of the cell-free supernatant to test for glucoamylase activity.

7. Add an equal volume of 1% starch solution to the cell-free broth. Incubate at 30^oC for 6
    hours or overnight if more convenient.

8. Use a semi-quantitative glucose test strip to measure the concentration of glucose in the 
    reacted mixture.

9. Dispose of used test samples and glucose test strips into disinfectant.
 

 
 
 
Safety
 

Standard microbiological safety procedures, including aseptic techniques, must be observed by teachers, technicians and students when carrying out this work.

Particular care should also be taken when using the centrifuge, and steps such as those described above should be taken to prevent the formation of aerosols.