Science Buddies: "Ask an Expert"

Hi, i need help as i cant seem to find the answers anywhere online! I want to spike bottled water with bacteria grown on nutrient agar. Do i just add a number of colonies to the bottled water and leave for a period of time?

Hi PHOEBIE, thanks for coming to the Ask An Expert forums!

Before we begin discussing the procedure itself, I suggest we take a look and think about the project overall. Specifically, what is the primary research question that you want to ask? In other words, why are you spiking bottled water with grown bacteria?

What is your hypothesis or prediction? Why do you think that? What will you be measuring? Do you have a control group? If so, what is it?

These are all good questions to be asking when beginning any project. Your procedure will probably depend on your answers to these questions. You may also want to reference our Project Guide: https://www.sciencebuddies.org/science- ... t-question

Feel free to ask us more questions! I'd love to help you out further!

Hi, thank you for the reply.
I am looking to spike bottled water to see if test methods are effective and over different periods of time. I need to see if i can just transfer known colonies from different agar plates into the bottled water and leave for different periods of time and then test for growth.

Hi PHOEBIE,

So, in theory, that shouldn't be a problem if you're just trying to add bacteria to the water. But if you are testing for growth, you're likely to encounter a problem.

Clean, bottled water technically cannot sustain bacterial growth. It's important to remember that bacteria, like us, are living organisms. And also like us, they need food and nutrients. Bottled water doesn't have much of that (some minerals and micronutrients), so the bacteria probably won't grow predictably well. It will more likely survive and sustain a certain number.

You may be able to get more reliable growth if you leave the water in the open. Living organisms are chemically dependent on carbon, and a lot of times microorganisms can get that from atmospheric carbon dioxide.

I'm honestly not entirely sure what to expect, but that's what I can offer. As long as there's some nutrients, bacteria should theoretically be able to grow. Hope that helps!