You determine your spore culture has a concentration of 2 x

You determine your spore culture has a concentration of 2 x 107 spores/ml. You dilute the culture by a factor of four and then recount. How many spores would you expect to see in the 0.2 mm x 0.2 mm x 0.1 mm volume, if you added 10 µl of the diluted culture to the hemocytometer? Assume no trypan blue was added.

Solution

A)

spore culture has a concentration = 2 x 107 spores/ml

spores volume =0.2 mm x 0.2 mm x 0.1 mm

if added 10 µl of the diluted culture to the hemocytometer

=?

spores volume=0.2 mm x 0.2 mm x 0.1 mm

=0.004 mm³

Move Volume = Final Volume / (DF -1)

=10 µl /(2-1)

=10 µl

Total Mixing Volume = Diluent Volume + Move Volume

=10 +10

=20.