Name: Jennifer A Buckner
Age: N/A
Location: N/A
Country: N/A
Date: N/A
Question:
I am in the ninth grade. I want to do a project on effective
ways to kill bacteria. I am looking for ways to grow bacteria and to tell
how much bacteria has been killed. Can anyone help me with a way to do this
experiment and do repeated test.
Thank You for your help.
Replies:
The easiest way would be to determine the number of living
bacteria present before and after treatment. You can do this by spreading
a small volume of a cell suspension on a nutrient agar surface in a petri
plate. After incubation for a day or two, you should see a number of
colonies. Each colony corresponds to a single living cell present in the
original suspension. Counting the colonies therefore gives you the number
of cells living cells present at the time of plating. You could compare
the numbers for treated and control samples to see how effective the
killing treatment was. Keep in mind that a confluent plate (with all
colonies run together) or a plate with no colonies will not give you any
information about the number of living cells. Therefore, it is necessary
to plate a number of dilutions for each sample. Then, at least one or
two plates will contain an appropriate number of cells for counting
(usually 30-300 colonies is a good number). All of this assumes that
you have access to some basic tools of microbiology. If your school does
not have the necessary equipment (autoclave, nutrient media, etc.),
contact someone at a local college. Often, these people are willing to
assist high school students in these projects.
NEWTON is an electronic community for Science, Math, and Computer Science K-12 Educators, sponsored and operated by Argonne National Laboratory's Educational Programs, Andrew Skipor, Ph.D., Head of Educational Programs.
