Replacement Petri Dish Media for...

[Simooligan]

Hi all

 

I am working on science fair, which is due Monday.

 

My teacher will not allow us to use anything in the classroom for some reason, including test tubes, cylinders, and petri dishes. So, instead, I came up with the idea to use..... plastic Tupperware.

 

I am growing bacteria. I know that in order for it to grow, the dish needs a media. Petri Dishes usually have the gelatin media already in it. Is there a substitute media I can make here at home to put in the plastic Tupperware?

 

Thanks for your assistance!

 

~Danny

[ecoli]

the media is LB (luria broth). It's essentially yeast extract and agar... you could potentially make it yourself.

 

However, I don't know if the tupperware would work. For one, if you close the lids, you're not going to get any air flow through it. If you leave it open, you're probably going to get contamination. Petri dishes a designed to prevent both these things.

[CharonY]

To be more precise LB is for the most part (10g) tryptone (tryptically digested casein) , half of it yeast extract (5g) and depending on formulation (Miller or Lennox) 5-10g NaCl. For agar slants you require to add 1.5 % agar into it.

 

This is a so-called complex medium and not only E. coli, but also copious other bacteria and fungi will grow on it. Generally it is not a good idea to grow bacteria under these conditions, if you cannot work sterile, as you cannot exclude that you might grow pathogens.

 

An alternative might be the use of minimal media (containing only the essential salts and vitamins) to limit unwanted growth, but this is far more laborious. In theory tupperware might work though. You have to thoroughly sterilize everything beforehand, and then use a large enough tupperware box. You only pour in a little bit if the medium into the dish so that you will enclose enough air if you seal it. If the box is large enough, there should be sufficent oxygen to grow some colonies. Still, I'd always advice to be careful working with bacteria.

[Simooligan]

Thanks for the advice Ecoli and CharonY

[DrDNA]

"due Monday"???

What the!?!..... that cavalier sense of urgency sounds familiar....boy!! what are you doing on the computer!? Are you already done with your homework?!?!?! If so, why aren't you reading a book?!?!

Where is your mother?!?! You just wait til I get home and get a hold of you!!

 

 

Seriously,

You may be in luck. It just so happens that I ran across this earlier today as I was searching for something else and noticed it because I thought it was interesting.....all can be found in your kitchen or at your local grocery store....gelatin, water, sugar, beef bouillon......

little muffin or cupcake pans or tins for the Pitre dishes.......

 

http://www.umsl.edu/~microbes/pdf/homemademedia.pdf

[ecoli]

Good find, Dr. DNA... I'm going to pass that along to my dad, he's a high school bio teacher and is always looking for stuff like that.

[DrDNA]

I do wonder which bacteria will grow or thrive in it. It certainly does seem to be limited in nutrients.

Simoo, you might need to try several different types of bacteria, but in my experience, ecoli seems to grow on a lot of things......

 

EDIT: I mean ecoli the bacteria, not the guy

[ecoli]

both are true, though, DrDNA.

 

I like to eat of variety of foods, as does my microbial namesake.

[toadyfinan]

Hey, how do you know if you are growing a pathogen? I'm pretty sure that my parents wouldn't be very happy if I started growing E. Coli either.

 

Also, Would just putting the petri dishes filled with the replacement agar in the basement work? I am an aspiring microbiologist and want to see how to grow colonies of bacteria myself.

[CharonY]

Without further analytical tests you wouldn't know what kind of bacteria you got (pathogenic or no). At least not until it is too late .

 

Do you mean incubating your plates in the basement? It depends on the bacteria. There are of course a number (actually most) that would grow below body temperature, but they grow slower. Your plates might dry out during that time. Also contamination would be a problem.