Date: December 2004
I'm doing a school project on groing bactiria on comon
houshold food products. I need a way to measure or count the bactiria
forming on the concoction of junk. How a fairly easy way to do it?
You would scrape all the bacteria off of the object in question and
resuspend them in a known volume (for example 10 mL) of saline (0.9% or
0.15 M NaCl) solution. You would then vigorously vortex this suspension to
break up any clumps of bacteria.Using a Petroff-Hauser counting chamber and
a microscope (40X), you would count the number of bacteria in one field and
then multiply by 250,000,000. This would give you the total number of
bacteria in the 10 mL suspension.
Ron Baker, Ph.D.
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Update: June 2012