Question for bacteria

[raghad]

Hi every one ,
I want to search the bacteria in food, compared to the food covered and food not covered
I want the impact of bacteria in the air for a wise man that he previously said about the descent of a disease in the days of the year not covered in the food and said that the disease is serious or fatal
My problem is:

1 - How can I know if these bacteria from food or mold from the air?

2-How do I know it is a dangerous bacteria and I do not know what its name because it is unknown?

3-Can I use animals to prove?

4-What is best to use foods or beverages, and is supposed to be eating the same in all trials?

plz help me


Thank you

[djschlesinger]

Hello,

Your projects is an excellent example of classic microbiology.

In response to your questions:

1. This will be a difficult question to answer. I would suggest designing your experiments with sterile controls. For example, if you decide to use a piece of potato as your food source, you should start with two potato slices. Wash one of them thoroughly with soap and water or even ethanol, to sterilize the surface and leave the other one as is. You could then compare the types of growth (color, size, shape, etc) on the surface of both slices. The potato slice that had been sterilized should only contain bacteria or mold from the air. The potato slice that was not washed may contain mold from the food and the air.

2. This would also be difficult to answer. You could start by performing a simple gram stain. You may also consider purchasing a biochemical testing kit for bacterial identification. Alternatively you could perform the biochemical tests on your own. This kind of experiment is standard in every introductory microbiology course (for example: http://web.fccj.org/~lnorman/unknowns.htm?index=2).

3. If you are asking if you can use an animal model to test the pathogenicity (or dangerousness) of any bacterial species you may isolate, then the answer would be no. Such experiments require very specialized research facilities and are performed under very strict state and federal guidelines.

4. I would suggest you start with something simple, such as a piece of fruit or vegetable. A potato is ideal because the surface can act as an excellent food source for bacteria and mold. If you are successful using a potato, you could move on to additional fruits or vegetables.

I hope this helps. Please let me know if you have additional questions.

-Dave

[deleted-71950]

Hello,

In answer to your first question you can use stain testing to determine if it is by mold vs bacteria. Also, most molds are fungi, thus you can take a sample and use a microscope to determine if it is bacteria or fungi.

2) I don't recommend that this project be done in a household environment. It would be better to conduct this in a labratory where control measures can be taken. Also to determine the strain of bacteria would be difficult, so I recommend isolating the bacteria you are looking for. Instead of trying to identify every single strain, try to identify a few generas of bacteria. This will make your project much easier

3) According to ISEF rules you cannot test on animals unless you have the ability to control the suffering caused to the animal. This form of research is strictly regulated.

4) You would most likely want to use some type of bread or fruits and vegetables.

Please post if you need any additional help.

[mbadtke]

In addition to the other excellent comments for question #4, you could also think about using a liquid in your experiment. The benefit of a liquid is that you could directly add a small portion to an agar plate and look for bacterial growth. Using a solid food would require you to try to move the bacteria or fungi to plates, which would introduce another step and variable. Either way would work well. Good luck!

Matt Badtke

[raghad]

Hi ,

thanks all for answers , I am really really happy .
I appreciate all of you because my religion telling me to thanks people : )

Hello,

Your projects is an excellent example of classic microbiology.

In response to your questions:

1. This will be a difficult question to answer. I would suggest designing your experiments with sterile controls. For example, if you decide to use a piece of potato as your food source, you should start with two potato slices. Wash one of them thoroughly with soap and water or even ethanol, to sterilize the surface and leave the other one as is. You could then compare the types of growth (color, size, shape, etc) on the surface of both slices. The potato slice that had been sterilized should only contain bacteria or mold from the air. The potato slice that was not washed may contain mold from the food and the air.

2. This would also be difficult to answer. You could start by performing a simple gram stain. You may also consider purchasing a biochemical testing kit for bacterial identification. Alternatively you could perform the biochemical tests on your own. This kind of experiment is standard in every introductory microbiology course (for example: http://web.fccj.org/~lnorman/unknowns.htm?index=2).

3. If you are asking if you can use an animal model to test the pathogenicity (or dangerousness) of any bacterial species you may isolate, then the answer would be no. Such experiments require very specialized research facilities and are performed under very strict state and federal guidelines.

4. I would suggest you start with something simple, such as a piece of fruit or vegetable. A potato is ideal because the surface can act as an excellent food source for bacteria and mold. If you are successful using a potato, you could move on to additional fruits or vegetables.

I hope this helps. Please let me know if you have additional questions.

-Dave

So what you suggested that I clean both slices. Then I covered one while I left the other uncovered. Right?

My second question is :
You already asked me to use 2 slices of potatoes. Do they have to be peeled (with no that brown skin) ?
and is it possible to use the same potato for more than once. For example, use 2 slices for today and the other 2 or 4 for next day?

It would be very appreciated if you could help me with this too:
How can I make this project for the only one bacteria,that you've talked about, without having to observe many typer of bacteria?

Thanks again

[djschlesinger]

Yes, that is correct. Cleaning both slices provides you with the best control.

For convenience it might be easier to use slices of an unpeeled potato. And you don't just have to use 2 slices. You can take one potato and cut it into an even number of slices and create two groups of slices. Does that make sense? You could use the same potato more than once if you refrigerate it after slicing.

A talked about one type of bacteria only as an example. It is likely that you will observe multiple types of organisms growing on the potato, not just bacteria, but mold as well. If you observe multiple organisms growing, you can still focus your experiment on only one or two types.

-Dave

[raghad]

Yes, that is correct. Cleaning both slices provides you with the best control.

For convenience it might be easier to use slices of an unpeeled potato. And you don't just have to use 2 slices. You can take one potato and cut it into an even number of slices and create two groups of slices. Does that make sense? You could use the same potato more than once if you refrigerate it after slicing.

A talked about one type of bacteria only as an example. It is likely that you will observe multiple types of organisms growing on the potato, not just bacteria, but mold as well. If you observe multiple organisms growing, you can still focus your experiment on only one or two types.

-Dave

thank so so much ..