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Name: Nick
Status: Student
Age: 11
Location: N/A
Country: N/A
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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