Science

[xinyi0111]

Anyone please help me? Can anyone define what is nutrient broth? Please, I need the answer urgently. Thankyou(:

[deleted-71791]

Hello xinyi0111,

Thanks for your question. Is this question for a science project? You can find more information online or at your local or school library in microbiology books. Here are some good places to start: http://en.wikipedia.org/wiki/Nutrient_broth You may also use Google.com or Schoolr.com to define what nutrient agar is.

Good luck!

[donnahardy2]

Hi,

Nutrient broth is a common culture medium used for growing all types of microorganisms and it does not contain a sugar source. Here is a recipe:

http://www.thelabrat.com/protocols/NutrientBroth.shtml

If you don’t have commercial nutrient agar available, you can substitute beef bouillon for a homemade medium.

The science buddies website has excellent information for the microbiological techniques:

https://www.sciencebuddies.org/science- ... ndex.shtml

Please let us know if you have any other questions.


Donna Hardy

[xinyi0111]

Hey! i have another question. Would you mind telling me what are the pros and cons of plum fruit vinegar, distilled white vinegar, concentrated organic brown rice, black beans vinegar and black vinegar? What are the good uses of it? (questions related to nutrient broth; if any of these vinegars could inhibit bacteria growth in it.)
I need it as soon as possible, THANKS(:

[donnahardy2]

Hi Xiny,

Vinegar contains acetic acid, which is very useful as an antimicrobial agent. Here are two reports using 3% acetic acid as an antimicrobial agent.

http://www.ncbi.nlm.nih.gov/pubmed/19286325

http://aem.asm.org/cgi/content/full/69/5/2959

I don't know what the effect of the other components in the various vinegars would be, but addition of vinegar to the nutrient broth would definitely inhibit microbial growth.

Please let me know what you are trying to do in your project.

Donna Hardy

[xinyi0111]

Oh it's okay. Let me ask another question: What are the chemical properties of various vinegar which allowed them to inhibit bacteria growth?

[xinyi0111]

By the way, for your information. I am doing a science project researching on how effective vinegar is for inhibiting bacteria growth. We chose to do on these following vinegars: concentrated brown rice vinegar, black beans vinegar, black vinegar, plum fruit vinegar and distilled white vinegar. What are the properties of these vinegars allow bacteria to grow? and the results was that concentrated brown rice is the most effective for bacteria to grow and plum fruit vinegar is the least effective. So i wonder if you can answer my question.
(:

[MelissaB]

The chemical property that I would guess is important is pH. I would suggest measuring the pH of the various vinegars and see if they differ, then see if that difference is correlated with their antimicrobial properties.

[xinyi0111]

The chemical property that I would guess is important is pH. I would suggest measuring the pH of the various vinegars and see if they differ, then see if that difference is correlated with their antimicrobial properties.

Hmm, then would you mind telling me where did you get this source from? because I need to have furher information on it.
And, can tell me some websites i can rely with for my project? :DD

[donnahardy2]

Hi Xiny,

The primary ingredient of all vinegars is acetic acid, and the concentration varies from 3 to 7%. You might check the label on the various vinegars to see if you can tell the exact amount of acetic acid that you added to each sample. Perhaps the difference in growth can be explained by the concentration of acetic acid. If all other parameters are identical, you would expect more inhibition of growth with a higher concentration of acetic acid.

If you did adjust the amount of vinegar added to each sample to ensure the acetic acid concentration was identical in each sample, then results are probably due to some other component in the vinegar. I could not find the exact chemical composition of brown rice vinegar, but many of the components of brown rice are probably present in the vinegar and may have affected the growth. Here is a website that includes the composition of brown rice; you will see that brown rice contains various vitamins, minerals and lipids.

http://nutritiondata.self.com/facts/cer ... sta/5707/2

Here is a paper that reports the chemical analysis of several varieties of plums:

http://pubs.acs.org/doi/pdf/10.1021/jf970032e


You choice of white vinegar is a good control because this vinegar contains only pure acetic acid.

How did you measure the rate of growth in your project? Were you using a single microorganism or a mixed culture?


Donna Hardy

[donnahardy2]

Hi Xiny,

Here’s some basic information on acetic acid.

http://en.wikipedia.org/wiki/Acetic_acid

Have you had chemistry yet? Here’s how to calculate the pH of acetic acid, which is a weak acid.

http://www.chemtutor.com/xacid.htm

The pH of a solution depends on the concentration of hydrogen ions. Vinegar usually contains about 5% acetic acid, or 5 grams per 100 ml and the molecular weight is 60 grams per mole:

5 g/100 ml x M/60 grams =0.00083 M

The dissociation constant or kA of acetic acid is 1.75 x 10 to the minus 5.

The concentration of hydrogen ions is the square root of the kA times the molar concentration of acetic acid, or .00012 M hydrogen ions, or about pH 4.

However, if you added acetic acid to nutrient broth, there would be some other buffering agents, like phosphate that would affect the pH, and it would be difficult to do the calculations.

It would be very helpful if you could describe your experiment. It would especially useful to know the dilution of acetic acid you used and the type of microorganisms you tested.


Donna Hardy