Science Buddies: "Ask an Expert"

I am doing a project on the antibiotic properties of Echinecea against nonpathogenic strain of E.coli. for my experiment I am using two species of Echinecea. Purpurea and Angustifolia. for each species I will make extracts of root/stem, root/leaf, leaf/stem, root,stem,leaf.cultures of E.coli will be placed on algea plates. and the culture will be measured each day for a certain period of time.

Can someONE TELL ME THEIR OPINION OF MY EXPERIMENT SETUP AND SUGGESTIONS? ANYONE

wILL THE ROOT EXTRACT, LEAVE EXTRACT, AND STEM EXTRACT FOR EACH SPECIES BE MY CONTROL? wHAT WILL BE THE VARIABLE, i GET MY EXPERMANT SETUP BUT I DONT GET WHICH WILL BE THE CONTROL AND VARIABLE

PLESE TELL ME IF YOU HAVE ANY SUGGESTIONS, AN OPINION, OR AN ANSWER TO MY QUESTION

In your experiment, you are testing the antibiotic properties of echinecea Purpurea and echinecea Angustifolia on bacterial cultures of E. coli. Therefore, your control setup would be a bacterial culture of E. coli without the addition of either species of echinecea. The variable you are testing is the effect of the different species of echinecea on the E. coli cultures.

Also, make sure you are being extremely careful while handling the E. coli.

You can make a homemade extract by gathering leaves/stem/root parts, running them in a blender, and squeezing the resulting paste in a cheesecloth. The liquid that comes out will be your extract.

The experiment sounds really interesting ^_^

Just a few tips:
For the E. coli, grow it on Luria Broth plates, and try to dilute the amount of E. coli there is on each plate, since if there's too many, counting the plates is a lot more difficult. The non-pathogenic strain of E. coli isn't particularly dangerous either, and the chance of getting sick from it is 1: 1billion .

Thanks alot, but how do I dilute an E.coli

Are there certain conditions I need to keep the E.coli under?

When I place them on the algea plates, do I pour the extract on them?

I was told that to measure the amount of baceria on the algea plates each day I should measure the halo arround it, is that right

Do you think that I should set a
certain period of time like 2 weeks, to study and measure the bacteria, or do I just keep measuring it till it disappers
If the Echinecea does clear out the bacteria? is it just going to disappear on the algea plate?

Thanks alot, I hope You could answer some of my questions, its okay if you can only answer some, thank you

Ok, so first, to dilute the E. coli, you need to have it in a solution, which would be the Luria Broth (the luria broth agar is what you grow the E. coli on) and take a predetermined amount of the E. coli "solution" and put it in another test tube that has only Luria Broth and no E. coli.

For example, you have a 10 mL sample of the E. coli solution
to dilute it to a 1: 10 ratio in comparision to the initial concentration,
you can take 1mL of the initial solution and add another 9mL of the clean Luria broth solution


To count the number of bacteria, you first have to plate it on the agar, which is taking a small amount of the solution (i took about .1 mL) and squirt it onto the middle of the plate.
Then, you take a small ring (it's like a thin long plastic or metal stick with a ring on the end that's clean) and spread the the E. coli around the plate. You spread it around half the plate at a time, turn it 90 degrees, spread it around the far half of the plate again, and turn the plate and spread it two more times to get the E. coli spread evenly around the plate.
(and you have to make sure, before you plate the bacteria, you mix the solution evenly, by holding the top of the test tube and kind of flicking it...)

The each individual E. coli on the plate will grow into a small yellow dot on the plate after being incubated for about a day. The plates need to be kept at a warm and constant temperature. To count the number of bacteria in the initial sample, just count the dots!

And I think you should definitely set a period of time to study the bacteria. The E. coli doesn't take much time to grow, so you can try many different periods of time, such as 1 day, 2 days, 1 week and see how the extract affects the E. coli.
If the Echinecea does kill off the bacteria, the bacteria won't grow on the plates (they'll be killed off before they can grow to a noticible dot).


Well, I hoped this helped some ^_^
and if you have any more questions, i'll try and answer them

Good luck!

Thank you very much

I dont get what the ring is , is it something that I can buy?

What do you mean by incubated

Do you have any idea on where I can pLace the bacteria to keep it under constant temperature?

I was thinking about putting the thermometer in myliving room on a certain temperature and never changing it till I'm done with my experiment, because this experiment will be done in my living room.
WILL THAT WORK? THANK YOU VERY MUCH

I AM SO SORRY, BUT I FORGOT SOMETHING, WHERE DO I PUT THE EXTRACT, DO I POUR IT ON THE E.COLI AFTER PUTTING IT ON THE ALGAE PLATES?

You can probably get the plating "ring" (it's kinda like that... ^^;;; i'm trying to find a picture of it...) from a biology teacher.
If you can't, you could probably use a metal wire (the wire has to have a very high melting point...) twisted into a loop at the end and attached to something that will insulate the wire so you can hold onto it (probably some aluminum around it, or something that won't heat up easily) since if you're going to use it multiple times, the wire has to be sterilized every time or otherwise you'll probably get slightly inaccurate results or other bacteria in the plate.

And when you keep the E. coli incubated, it's just keeping it at a constant tempterature, about 30 degrees C or room temperature, but it'll take longer for the E. coli to grow.

Is it possible for you to find a school lab to do your experiment in?
Especially since plating the E. coli requires you to sterilize everything that you're using, (like when i did something like this... bunsen burners to pressure cookers...)

When you add the extract, i think the best way is after you dilute the solution of E. coli, add maybe a few drops of the extract (or however much you want to add) to the solution then plate it.


And i found a site that could probably explain the diluting process a bit better, though it doesn't use E. coli, but the concept is the same
http://faculty.plattsburgh.edu/donald.s ... titre.html


Hopefully this described it a little better ^_^;;;

Thank you so much for answering my questions

When I'm buying the E.coli, do I ask for an E.coli solution, or an E.coli culture?, or will the culture be in the solution?


Thanks alot for putting in your time to answer my questions, I highlg appreciate it, thank you

You can get it in a dried form when you buy it. It's probably the easiest way. Then you take the dried E. coli and put it in the broth.

[ THANK YOU

You're welcome ^_^

If you run into any other problems, feel free to ask
((i'll try and get an answer... XD))

Hi, um you said something about me needing to sterializd every thing I use on the bacteria, Do you mean jus the ring you talked about,or can you tell me what I need to sterialize?

thanks