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bacterial count
Moderators: AmyCowen, kgudger, bfinio, MadelineB, Moderators
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wildmanx2
- Posts: 1
- Joined: Thu Nov 20, 2008 5:43 pm
- Occupation: student
- Project Question: I('m in 6th grade. I'm doing a project to find out which has more germs: a human's mouth, a dog's mouth, a school toilet seat, or a school cafeteria table. I am having trouble finding out how to count the bacteria colonies without a microscope. Thanks
- Project Due Date: The procedure section of the project must be turned in 12/12/08
- Project Status: I am conducting my research
bacterial count
Help, please! I'm looking for a way to count bacterial colonies on an agar plate without a microscope. ( Will be doing swabs of mouths, cafeteria tables & toilet seats). Any ideas or references appreciated!! Thanks.
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ScienceExpert123
- Former Expert
- Posts: 102
- Joined: Sat Sep 20, 2008 9:26 am
- Occupation: Student
- Project Question: n/a
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- Project Status: Not applicable
Re: bacterial count
dear wildmanx2,
Sounds like a great project. To plate bacteria you should buy petri dishes (here is a science fair project kit http://www.amazon.com/Petri-Dishes-Agar ... 453&sr=8-2) (here are just petri dishes: http://www.amazon.com/Learning-Resource ... 453&sr=8-3) (http://www.amazon.com/Petri-Sterile-Dis ... 453&sr=8-4). You should swab the samples with wet swabs and then put it onto the surface of the petri dish. Wait a few days and then you could probably count the colonies by hand or with a magnifying glass. Remember BE CAREFUL when working with bacteria because it can be dangerous. You should wear proper gloves (latex (if your not alergic), vinyl, or nitrile) when working with the petri dishes/bacteria. Also, keep the petri dishes away from people, food, pets, and other substances; keep it in an area away from these things.
good luck,
scienceexpert123
Sounds like a great project. To plate bacteria you should buy petri dishes (here is a science fair project kit http://www.amazon.com/Petri-Dishes-Agar ... 453&sr=8-2) (here are just petri dishes: http://www.amazon.com/Learning-Resource ... 453&sr=8-3) (http://www.amazon.com/Petri-Sterile-Dis ... 453&sr=8-4). You should swab the samples with wet swabs and then put it onto the surface of the petri dish. Wait a few days and then you could probably count the colonies by hand or with a magnifying glass. Remember BE CAREFUL when working with bacteria because it can be dangerous. You should wear proper gloves (latex (if your not alergic), vinyl, or nitrile) when working with the petri dishes/bacteria. Also, keep the petri dishes away from people, food, pets, and other substances; keep it in an area away from these things.
good luck,
scienceexpert123
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deleted-71447
- Former Expert
- Posts: 1019
- Joined: Fri Oct 28, 2005 11:43 am
- Occupation: Research Hydrologist
- Project Question: n/a
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- Project Status: Not applicable
Re: bacterial count
Hi,
There is a Science Buddies project on this topic that gives detailed information about procedures and background information:
http://www.sciencebuddies.com/science-f ... A&from=TSW
Good luck!
Chris
There is a Science Buddies project on this topic that gives detailed information about procedures and background information:
http://www.sciencebuddies.com/science-f ... A&from=TSW
Good luck!
Chris
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deleted-71670
- Former Expert
- Posts: 137
- Joined: Tue Sep 18, 2007 5:06 pm
- Occupation: science journalist
- Project Question: n/a
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- Project Status: Not applicable
Re: bacterial count
Hi wildmanx2,
With swabs from mouths and cafeteria tables, within days or a week you're sure to see bit colonies--no microscope necessary! (The amount of time depends on the kind of microbes and what temperature you incubate the plates at.) Keep in mind, if you're collecting bacteria from people's mouths you'll want to be careful with your cultures--some bacteria aren't dangerous when there are just a few, but a colony will contain thousands that could be dangerous). You should seal your Petri dishes with tape once you've swabbed them.
One convenient way to count colonies, especially if you have a lot, is to make a grid, on a circular piece of transparent plastic, that you will place over the Petri dish. Then you can monitor colony appearance in each grid square.
Since your samples are likely to have several different species, you might keep track of when the colonies appear (some will grow quickly, others slowly) and what they look like. Students often take pictures of their plates--a regular camera will do--to put on their science fair display.
Keep in mind you may get fungi as well as bacteria--these will take longer to grow.
good luck
With swabs from mouths and cafeteria tables, within days or a week you're sure to see bit colonies--no microscope necessary! (The amount of time depends on the kind of microbes and what temperature you incubate the plates at.) Keep in mind, if you're collecting bacteria from people's mouths you'll want to be careful with your cultures--some bacteria aren't dangerous when there are just a few, but a colony will contain thousands that could be dangerous). You should seal your Petri dishes with tape once you've swabbed them.
One convenient way to count colonies, especially if you have a lot, is to make a grid, on a circular piece of transparent plastic, that you will place over the Petri dish. Then you can monitor colony appearance in each grid square.
Since your samples are likely to have several different species, you might keep track of when the colonies appear (some will grow quickly, others slowly) and what they look like. Students often take pictures of their plates--a regular camera will do--to put on their science fair display.
Keep in mind you may get fungi as well as bacteria--these will take longer to grow.
good luck
Amber Dance
Science Buddy
Science Buddy