E.Coli growth

About microscopic forms of life, including Bacteria, Archea, protozoans, algae and fungi. Topics relating to viruses, viroids and prions also belong here.

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E.Coli growth

Post by Raoul » Thu Feb 22, 2007 2:23 pm

I was aiming to investigate antibiotic effect on the growth of E.coli in petri dishes, by dousing a paper disk 5mm in diameter and placing it in the dish containg the E.coli, then leaving for 48 hours to grow. All concentrations were conducted three times. But as my results show it seems that the antibiotic(which i dont not know what it was) promotes groth of colonies.

anyone got any idea how this is possible? results are shown below

Number of colonies
Antibiotic concentration (%) Average
70% 344000
60% 264000
50% 40000
40% 8000
30% 0
20% 0
10% 0
0% 0

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Post by Vagabond » Thu Feb 22, 2007 2:53 pm

are you sure it is an antibotic? or could it be a selective type suppliment (that is to say like HAT media or something?)

Are your bugs transfected with any transgenes?

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Post by Raoul » Thu Feb 22, 2007 3:06 pm

I beleieve that the Antibiotic was Savlon but i cannot be 100% sure.

The other set of results i gain were from using Staphylococcus, and these as expected show the antibiotic reducing growth of the bacteria.

there are no foreign genes, none which i have inserted myself

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Post by Mhlengi » Tue Mar 06, 2007 4:57 pm

Did u check the concentrations of your antibiotic because they ere good chances that it was too dilute to carry out its antibiotic role.It that case you'd observe normal grown or promotion of grown with respect to the media you used rather that with that to the antibiotic.

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Post by canalon » Tue Mar 06, 2007 9:18 pm

Savlon is a brand name. Worse the active agent is not the same in the different formulas. And they are not antibiotics but antiseptic.

But I do not really understand your experiment. If I read what you did, you doused paper disks with the anticrobial and put them in the middle of petri plates. How were your plates inoculated with bacteria? What or where are you counting the colonies?

Because in disk diffusion, there are no colonies to count, just an inhibition diamenter to measure...

Science has proof without any certainty. Creationists have certainty without
any proof. (Ashley Montague)

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