Has anyone had any success with growing bacteria ?

[ladykayaker]

Has anyone had any success with growing bacteria ?

ds 14 is attempting - without success - to grow bacteria. He is using Agar, sterile petri dish, and took swabs around the house including inside our very smelly trash can. Nothing seems to be growing.

Does anyone have any suggestions on what could be wrong?

[Mom22ns]

Where are the plates? You'll want them in a warm place (shouldn't be hard this time of year) and make sure they aren't in direct sunlight.

 

We did take swabs around our house last year during Biology. It was a bit slow to get growth since we didn't have anyplace over 60 degrees in our house (it was winter), but they did grow eventually.

[BibleBeltCatholicMom]

I've grown it w/o even trying so I can't imagine why you can't get anything going.

 

I think that if you'll lightly spritz a slice of bread with water, seal it in a ziplock, place it in a sunny window and don't move it, you should soon see mold growing.

 

You will difinately retard growth if you move it around exposing the underside to light but even then, it'll usually grow.

 

After you've successfully gown it, you can try exposing the bread slice to different surfaces to see if you notice a difference in what you're growing. Touch the bread to the trash can or whatever and then spritz and seal.

 

Sealing in the bag and placing in the window creates a warm, moist environment w/o special equipment but you have to make sure not to expose the under side.

 

If you want something slightly more high tech, you might consider contacting your local water quality volunteer group if you have one. Part of the monthly evaluation of water quality is to put a water sample in a dish with a medium (I forget what) and put it in a home-built incubator made with a night light and styrofoam ice chest. When they stopped letting under 18s particiate in training I quit them and can no longer remember some of the stuff they use but I bet they'll tell you. It's a local state agency wking with the epa, called different things in different states.

[ladykayaker]

Thanks for the replies. I believe mold is different to bacteria. Mold is a fungi with a nucleus, yet bacteria do not have a nucleus. For his biology project he is specifically dealing with bacteria. He is taking swabs from around the house -wanting to prove that there is bacteria all around us. I do not keep a particularly sterile home, never use lysol etc, so there should be bacteria, certainly in our trash can!

 

He is trying to grow it on his shelf above his desk, average indoor light, temp around 78 to 80 in the house. Does that seem warm enough, or should he place it outdoors where it will be considerably warmer ?

 

Are there any differences with Agar - the one we have doesn't specifically say it is nutrient Agar, is that necessary ?

[Myra]

We grew our cultures using a jello mix instead of agar in petri dishes straight from the dishwasher. After exposing to different areas (bathroom, sink, etc) we put them directly into a closet and forgot about them for a few days. Worked fine.

 

Myra

[mamato4]

Good point about using tap water.

 

OP, did you guys make the agar or bought nutrient agar ready-made and ds melted it and poured it into a petri dish? Agar has to have nutrients in it for bacteria to grow. In a microbiology lab, there are different types of plates used, with different ingredients in them, depending on what bacteria you want to grow.

 

Used to be a great spot for warmth is the top of a refrigerator since all the heat comes out the top. The refrigerators now have the heat escaping from the bottom. Do you have a garage and are you having a warm spell where you live? Try placing it in the garage since it is warmer than inside the house. An environment in the 90's with humidity, but not in direct sunlight, is preferable to room temp. Think body temperature, and that's the temp you want the plate to be in.

 

HTH!

Anna (who used to work as a microbiologist)

[chepyl]

In 4th grade my science project was growing bacteria. I was very successful. My mom bought small glass bowls, filled them with tomato juice or soup.....I can't remember. Then I took deans around the house. We left them to grow sitting on top of the hot water heater. The warmth of the closet really promoted their growth. The dishes were covered....plastic wrap, I think. It was sooo gross!!!

[momtotkbb]

We used the bacteria kit from HomeTrainingtools.com last year and had no problem getting bacteria to grow. The directions called for placing the covered petri-dishes in a warm dark place -- we used a basement storage room. There were a few that grew very little bacteria and others that grew too much for my comfort. We then tested various cleaners and anti-biotic discs.

[happygrrl]

Non-nutrient agar is not really suitable for growing bacteria. Nutrient agar contains beef broth and yeast extracts for optimum growth- it is also selective for non-pathogenic bacteria. I would try nutrient agar for sure! The other agars out there are selective for different organisms (differing in ph, for example)

 

Here is a good introduction to agar.

 

Hope that helps!

[angela in ohio]

We used the bacteria kit from HomeTrainingtools.com last year and had no problem getting bacteria to grow. The directions called for placing the covered petri-dishes in a warm dark place -- we used a basement storage room. There were a few that grew very little bacteria and others that grew too much for my comfort. We then tested various cleaners and anti-biotic discs.

 

Same here. Great kit.

 

We had suprising results: mouths (cats, kids) were pretty clean, as were toilets and bathroom sink handles. It was the back of the refrigerator handle that grew an entire civilization in the dish. Ack! :glare: We also got a few from door handles and kitchen sink handles.

 

We are going to try it again with public places (ATM, bathroom, etc.) and see what we find.

[ladykayaker]

I think we have just plain Agar and not nutrient Agar. ugh. I will have to find some of that instead. I like the idea of trying with jello - can you still see the bacteria under a microscope - the color doesn't interfere ?

We have borehole water, so there shouldn't be any chlorine in our water.

ds has now put out a new set in the garage, should be much warmer than in the house - silly me for not thinking of that.

[brandigirl]

Try agar with sheep's blood works like a charm.

[mom4peace]

Any agar can grow pathogens. Be careful. Don't open petri dishes, aside from when you add bleach before disposing of them.

 

We built a simple incubator. Here's a link to that adventure: A Homemade Incubator and Inquiry Science.

[aprilleigh]

I'm a microbiologist. The water is irrelevant unless you're trying to grow sensitive bacteria, which you clearly aren't. However, plain agar would definitely explain the problems you're having. Without nutrient the bacteria won't grow. If finding nutrient agar is a problem, try adding powdered bouillon to the agar you do have - you shouldn't have any other problems unless you're trying to grow lab strains (usually need special nutrients because they've been crippled so they're unlikely to grow outside a lab environment) or weird bacteria of some sort (you probably will have a hard time growing some of the bacteria that can be obtained by swabbing your mouth, but other species from the same swab will grow happily on bouillon-laced agar.

 

Try making bouillon agar at normal strength (1 tsp per cup of prepared agar) and half strength - normal strength should be just fine (after all, if you leave the bouillon on the counter it will eventually become contaminated), but the salt in full-strength bouillon will likely prevent many species from growing. If you try both you can decide which works better.

[ladykayaker]

However, plain agar would definitely explain the problems you're having. Without nutrient the bacteria won't grow.

 

Thanks April, we now have some nutrient agar - and it is working! There are bacteria EVERYWHERE !

[Candid]

My dad was a microbiologist and I can remember talking to him about this in regards to a home experiment a friend's child was running. He felt the best thing was to go ahead and purchase bacteria from a scientific source (in her case she was trying to study the effectiveness of antibacterial products). If you just go around your house, you really don't know what you are getting: mold, bacteria, etc. He got a little frown on his face and told me, he thought the child's teacher should have guided her better in designing her experiment so the scientist had total control of all variables including the bacteria.

 

I also agree with using distilled water.

[aprilleigh]

That's a complaint I often have about home science experiments in this field, and the one you describe in particular has the potential to provide really bizarre results from random bacteria.