how do I grow bacteria in petri dish

[kevlar551]

Hello, I am working on a science fair project that involves growing bacteria in a Petri dish. I am going to build an incubator and would like to know how I should go about growing the bacteria. Should I just plop the samples in the incubator and turn it on, or is there more to it?

[DV8 2XL]

Ya, there is more to it. You need the right medium to grow the organisms on and the right temperature and humidity. Of course you must inoculate the plates with what ever it is you want to raise.

 

Best to start with a Google search.

[akcapr]

You need agar and petri dishes and your bacteria basically.

[jowrose]

Agar is relatively simple to make, but it's not as good as agar you could buy on Ebay or other online stores. It involves gelatin, beef bouillion, and sugar. I've made several petri dishes full of it, but have only succeeded in growing mold... The hardest thing to do is keep the dishes from being contaminated, especially if you're planning on keeping the samples in your basement.

[Meti]

You can do a simple Google search for "Agar Petri Dishes", and you will get what you need. They are simply Petri dishes with "food" for the bacteria evenly spread at the bottom. They are fairly cheap, and you can get them in bulk. So you really shouldn't worry about "contamination", being as they are prepared for you.

[akcapr]

Bacteria are amazingly easy to grow.

[Yggdrasil]

However, unless you know and practice proper sterile technique, it's also amazingly easy to grow other contaminants along with your bacteria.

[kevlar551]

what is a simple way to prevent contamination while i am growing bacteria because yeah I do not have a high tech lab being that this is an 8th grade science project.

[RyanJ]

what is a simple way to prevent contamination while i am growing bacteria because yeah I do not have a high tech lab being that this is an 8th grade science project.

 

Put them in a sealed container. Before you use the petri dish also leave it under UV light for a few days before as that should kil most of the bacteria that are on there already

 

Cheers,

 

Ryan Jones

[Yggdrasil]

what is a simple way to prevent contamination while i am growing bacteria because yeah I do not have a high tech lab being that this is an 8th grade science project.

 

http://structbio.vanderbilt.edu/chazin/wisdom/labpro/sterile.html

 

Here's the first page from google that pops up from a search on sterile technique. In addition to working with a bunsen burner flame, I would also recommend wiping your bench with isopropanol (rubbing alcohol) before working with the bacteria, and working in an area that isn't close to any ventilation ducts which may increase the flow of dust particles around your bench area.

[Pleiades]

Agar is NOT the same as gelatin, Gelatin is made from boiled collagen from animals, and agar is made from seaweed. You can grow bacteria on a gelatin medium but usually not as well as you can on an agar one. Agar can be bought from the store (I’ve seen big bags of it in stores stocking Asian foodstuffs) you will often see it as a vegetarian alternative to gelatin. You make it just like Jello; mix the agar and nutrients in with hot water, pour it into the Petri dishes and let them cool; you can probably find some info on the internet about what to add for nutrients.

[akcapr]

there are different types of agar some are based on beef.

[leidiot]

I thought the agar petri dishes are already stirile so you just have to pop in the bactieria and quickly close it

[akcapr]

well the agar i have used is liquid, which you pour into dishes and then let cool then smear your sample on it.

[Caver451]

Sorry to bring up a slightly old post, but...

 

First, I would suggest buying the proper supplies. They're pretty inexpensive, and since this is the first time you're doing something like this, you really want to remove as many unknowns as possible. In other words, concentrate on growing your bacteria, instead of wondering if your homemade supermarket agar is good or not.

 

A good place to buy supplies like this is:

 

http://www.hometrainingtools.com/catalog/life-science-biology/cat_microscopic-life.html

 

I've ordered a few things from them in the past (in particular, some oleic acid for what turned out to be a very messy ferrofluid experiment) and they are pretty prompt with the shipping.

 

Second, I strongly suggest, as other have as well, to read up and learn as much of the "why" as you can. We can tell you how to do it, but then you haven't learned anything except how to follow instructions. Knowing "why", instead of just "how", is most of the fun!

 

One fantastic source of information is... your instructor at school! Believe me, nothing thrills a teacher more than a student showing a genuine interest and taking the time to ask them questions after school or after class. Just takes a few minutes, and believe me, asking your teacher for advice will almost certainly affect your grade for the better.

 

Don't just ask your teacher "How do I do this?" Ask specific questions, "I want to use agar as my growing medium. What is the proper way to store, prepare and handle agar?" Your teacher may very well give you some, or help you prepare it.

 

You don't need a big lab to grow bacteria, but you do need to learn the procedures for keeping things--including yourself--as sterile as possible. Washing your hands well, wearing a face mask and latex gloves, and keeping your work area clean go a long way.

 

Give yourself plenty of time to get your equipment, and to run a few tests. Your first few attempts may fail in "amusing" ways, and it might take a few tries to get it right. Your failures are as important as your successes! Keep a log of exactly what you did, what happened, and why you believe it didn't work. I can't stress how important this is! How well you keep records of what you did is more important than bringing in a petri dish full of goop!

 

Finally, there are a lot of different forums on this website. You might be able to get more specific information and advice on the Biology forums.

 

Good luck!

 

-Caver

[rakuenso]

i've grown many home cultures b4... nearly all of them suffered contaminatinon issues, it is ridiculously difficult without a sterile lab. its essential that you heat up your inoculating rod before streaking the plates

[groovychick__]

what shouldn't i do when anoculating a petri dish?

[hermanntrude]

eat horse manure?

 

punch people?

 

make bombs?

 

shoplift?

 

wear red with orange?

 

there are lots of things you shouldnt do while innoculating a petri dish