Bacteria Won't Grow In Petri Dishes. HELP!
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Bacteria Won't Grow In Petri Dishes. HELP!
Hi, I'm in seventh grade and working on a science fair project which is: how well do disinfectants really work? This is my second time I have tried this experiment and I'm getting the same results. Its been about two days and I'm still not seeing any growth except for the condensation on the lids. I feel like I'm doing everything right. I swabed the counter with a cotton swab, transfered it onto the petri dishes starting from the center to edge all the way around. Then I gently tapes the lids shut and put them face down in a cardboard box that's missing a side so I can let air in. I have the box around 90 degrees. What am I doing wrong?
Re: Bacteria Won't Grow In Petri Dishes. HELP!
Hello there!
I advise that you carry out all experimentation for this project at school under the guidance of a science-trained adult. Although counter-bacteria typically isn't as harmful as other bacterial agents, whenever you are growing anything into a culture, this needs to be done in a hazard free, sterile setting, and under the supervision of your teacher.
If your teacher doesn't have the necessary equipment to grow bacteria (such as sterile petri dishes and an incubator) you might want to reach out to a local high-school science teacher so that you can conduct your experiment there.
One of the first problems I'm hearing is the place in which you're incubating. Once you are in a science classroom for your project, your bacteria should be heated in a 37 degree Celsius environment in an incubator, which might be why they're not growing. Also, you should parafilm half of the plate to avoid contamination. make sure you are using a sterile swab dipped in sterile ddH2O, and swabbing it on a sterile agar-petri dish (oh, did I mention, sterile?
)
Also, what kind of agar are you using? Technically agar is JUST the support for the growth of microorganisms. Nutrients have to be added to agar for bacteria to feed on and grow.
Otherwise it sounds like you're doing everything right... you might want to ask your teacher what she suggests as far as running the experiment.
Let me know if you have trouble contacting a science professional and we can find a way to work out a safe, home alternative for your project.
Stay Nerdy!
lmp1341
I advise that you carry out all experimentation for this project at school under the guidance of a science-trained adult. Although counter-bacteria typically isn't as harmful as other bacterial agents, whenever you are growing anything into a culture, this needs to be done in a hazard free, sterile setting, and under the supervision of your teacher.
If your teacher doesn't have the necessary equipment to grow bacteria (such as sterile petri dishes and an incubator) you might want to reach out to a local high-school science teacher so that you can conduct your experiment there.
One of the first problems I'm hearing is the place in which you're incubating. Once you are in a science classroom for your project, your bacteria should be heated in a 37 degree Celsius environment in an incubator, which might be why they're not growing. Also, you should parafilm half of the plate to avoid contamination. make sure you are using a sterile swab dipped in sterile ddH2O, and swabbing it on a sterile agar-petri dish (oh, did I mention, sterile?
)Also, what kind of agar are you using? Technically agar is JUST the support for the growth of microorganisms. Nutrients have to be added to agar for bacteria to feed on and grow.
Otherwise it sounds like you're doing everything right... you might want to ask your teacher what she suggests as far as running the experiment.
Let me know if you have trouble contacting a science professional and we can find a way to work out a safe, home alternative for your project.
Stay Nerdy!
lmp1341
Re: Bacteria Won't Grow In Petri Dishes. HELP!
Thank you so much for responding. I am using this a kit from amazon with agar already in the petri dishes, I think it said it was LB agar. Also, It would be a lot better if I could get this project done at my home because I don't have the time or ability to contact a science teacher, and I'm doing this project with the help of my mom. I had the petri dishes set up in a small room in a box next to a portable heater, I've been trying to keep the tempature at 90 degrees as much as possible. Do you think I should keep waiting to see if any bacteria starts to grow, or should I just try again, because I don't have a lot of time to finish this. Again, Thanks so much for the feedback
Re: Bacteria Won't Grow In Petri Dishes. HELP!
Ah, I understand. That's no problem, we can make something work!
Make sure you are following the guide provided with the Amazon kit, and if there isn't one, I recommend following this protocol.
https://learning-center.homesciencetool ... ent-guide/
Another tip I have is to read this link: https://www.stevespanglerscience.com/la ... -bacteria/
You also may want to consider making your own agar, but even in the kit, one of the biggest things is to make sure that you have NUTRIENT agar, otherwise, there is no food for the bacteria to consume and they will not grow into colonies.
These links should be helpful, but let me know if you're still having trouble once you've redone it.
Just a reminder, while most environmental bacteria are not harmful to healthy individuals, once concentrated in colonies, they can be hazardous.
To minimize risk, wear disposable gloves while handling bacteria, and thoroughly wash your hands before and after. Never eat or drink during bacteria studies, nor inhale or ingest growing cultures. Work in a draft-free room and reduce airflow as much as possible. Keep petri dishes with cultured mediums closed—preferably taped shut—unless sampling or disinfecting. Even then, remove the petri dish only enough to insert your implement or cover medium with bleach or 70% isopropyl alcohol.
When finished experimenting, seal dishes in a plastic bag and dispose. Cover accidental breaks or spills with bleach or alcohol for 10 minutes, then carefully sweep up, seal in a plastic bag, and discard.
Best of luck!
lmp1341
Make sure you are following the guide provided with the Amazon kit, and if there isn't one, I recommend following this protocol.
https://learning-center.homesciencetool ... ent-guide/
Another tip I have is to read this link: https://www.stevespanglerscience.com/la ... -bacteria/
You also may want to consider making your own agar, but even in the kit, one of the biggest things is to make sure that you have NUTRIENT agar, otherwise, there is no food for the bacteria to consume and they will not grow into colonies.
These links should be helpful, but let me know if you're still having trouble once you've redone it.
Just a reminder, while most environmental bacteria are not harmful to healthy individuals, once concentrated in colonies, they can be hazardous.
To minimize risk, wear disposable gloves while handling bacteria, and thoroughly wash your hands before and after. Never eat or drink during bacteria studies, nor inhale or ingest growing cultures. Work in a draft-free room and reduce airflow as much as possible. Keep petri dishes with cultured mediums closed—preferably taped shut—unless sampling or disinfecting. Even then, remove the petri dish only enough to insert your implement or cover medium with bleach or 70% isopropyl alcohol.
When finished experimenting, seal dishes in a plastic bag and dispose. Cover accidental breaks or spills with bleach or alcohol for 10 minutes, then carefully sweep up, seal in a plastic bag, and discard.
Best of luck!
lmp1341
Re: Bacteria Won't Grow In Petri Dishes. HELP!
Thank you so much! I will definitley try out your tips
Re: Bacteria Won't Grow In Petri Dishes. HELP!
You're very welcome! Can't wait to hear if it works out for you!