Tiny titans E coli didn't grow

[VIPawar7]

Good morning,

Last week my son performed the Silver nanoparticles neutralizing E coli experiment. Even though we followed all the steps in a college lab where we used an incubator, the E coli did not grow on any of the agar plates.
We are not sure whether the freeze dried E coli we used was not a good sample or the agar plates were not optimal or unknown reason.

The instructions for reconstitution of E coli were conflicting. On the project outline it is mentioned "Take out your E. coli culture and follow the instructions in the kit to reconstitute the dried bacteria. Wait 5 minutes after reconstituting, then mix the gently shake to mix the bacterial suspension one more time."
However, on the instructions in the kit, it is mentioned that we should incubate the broth overnight to make sure the E coli will grow well on agar plates.
As we had to complete the experiment at the assigned time a the college lab, we placed the reconstituted solution in an incubator for half an hour and proceeded with the experiment.

Could you please clarify whether we should wait for five minutes after reconstitution or whether keeping the reconstituted solution overnight is required?

We will repeat the experiment again. We would greatly appreciate your thoughts and recommendations on this.

Thanks


[Administrator note: Project url: https://www.sciencebuddies.org/science- ... i-bacteria ]

[Phoebeclancy]

Based on the in formation you have provided and reading the online experiment, I would let the bacteria sit overnight so that the solution could grow to sufficient numbers. The online instructions says to follow the kit instructions which tells you to wait overnight so that would make the most sense. I hope this helps!