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Thread: Someone help me please !

  1. #1 Someone help me please ! 
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    Hi, i need someone's help as fast as possible. I'm doing a science fair project and it's due on Wednesday. I'm trying to grow bacteria from the saliva in agar agar powder mixed with water (which is turns into jelly which is what you grow the bacteria in) . I searched online and it says to grow it in hot temperature and a dark place. I left it in my attic for two nights and it still hasn't grown anything at all. It looks the same from when i put it in and it's sealed in a petri dish. Should i not seal it ? Am i doing something wrong ? Does anybody have any suggestions ? Maybe advice ? HELP ?

    Please help me...Anybody ! :?


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  3. #2  
    Universal Mind John Galt's Avatar
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    nerdpop7 I really wish I could help you. Unlike some who come on here looking for help you have made a serious attempt at find out what to do, it just hasn't worked.

    This will seem little comfort to you at this point, but the one thing you can learn from this is the importance of starting any project early, to allow for the unexpected. If you can take that lesson on board it will serve you very well for the rest of your life: much more valuable than learning how to grow bacteria from saliva. :wink:

    Hopefully someone here will come up with a solution. Good luck.


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  4. #3  
    Forum Cosmic Wizard i_feel_tiredsleepy's Avatar
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    When did you do the swab. If you put the saliva sample into the agar while it was still liquid after pouring you may have killed all the bacteria. A proper agar plate requires some sugar and nutrients for the bacteria to live off of. Agar itself is indigestible by bacteria, which makes it a great platform for growth, but some yeast extract and sugar would be necessary for the bacteria to have something to live off of.

    As to the rest, sealing it is good, otherwise you get contamination from the air. The best temperature to grow bacteria from your saliva in is 37 C, but this is difficult without an incubator. If you can place it somewhere near a heater so it is slightly above room temperature, and keep it covered so that it doesn't dry out, that should work fine. Not too close to the heater though, you don't want it to get dried out. It is also a good idea to flip the petri dish upside down, this helps keep the dish from drying out as well as preventing the condensation from falling back into the colonies.
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  5. #4  
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    Moist, warm and depending on the bacteria, light or dark. Bacteria also like sugars and other organic matter. If you make a chicken broth jello and you QTip a dirty surface like a toilet or fish or trashcan, an then you smear that back on the brothy Jello. You should be able to get a sustainable colony if it is in a warm place and covered.
    http://wiki.answers.com/Q/What_are_t...owing_bacteria




    Bacteria are single celled organisms that can only be seen with a microscope. They are so small that scientists measure them in micrometers. A micrometer is equal to one millionth of a meter. On average, a bacterium is equal to one micrometer long. This would mean that the head of a pin could hold hundreds of thousands of these microorganisms.

    In order for bacteria to grow and reproduce they need nutrients and other outside factors. The nutrients are absorbed through pores in the cell wall and passed into the cytoplasm. Some examples of the factors important to cell growth are oxygen, temperature and pH level. A thermophile grows at high temperatures, an acidophile grows at low pH, and an osmophile grows at high solute concentration, are according to textbookofbacteriolgy.com, which shows conditions.
    http://www.freeonlineresearchpapers....h-requirements


    IFT; Your answer is probably best, so let me ask you a question or two;

    If the water used was tap water, that is containing chlorine, wouldn't that also kill off the bacteria potential from growth for awhile?

    Is it possible results, are simple not visible, at this point? How long would should it take for this combination to show results?

    Would you maybe suggest making several samples, with distilled/rain, especially if a puddle of rainwater is available, water (leaving current sample alone) and placing them under various conditions. Warm (80F), dim places and so on to a couple samples under very moist conditions, say setting a wet rag in a closed area?

    I'll leave my research on the post for references.
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  6. #5  
    Forum Cosmic Wizard i_feel_tiredsleepy's Avatar
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    Quote Originally Posted by jackson33

    If the water used was tap water, that is containing chlorine, wouldn't that also kill off the bacteria potential from growth for awhile?
    Tap water is often used to make agar plates so I don't think that would be a problem.

    Quote Originally Posted by jackson33
    Is it possible results, are simple not visible, at this point? How long would should it take for this combination to show results?
    2-3 days is usually more than enough to see some colonies if they're gonna be there.

    Quote Originally Posted by jackson33
    Would you maybe suggest making several samples, with distilled/rain, especially if a puddle of rainwater is available, water (leaving current sample alone) and placing them under various conditions. Warm (80F), dim places and so on to a couple samples under very moist conditions, say setting a wet rag in a closed area?

    I'll leave my research on the post for references.
    It couldn't hurt, especially for a high school project.
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