(Newswire.net — October 4, 2018) — Although invisible to the naked eye, bacteria can be found on virtually any surface because they can thrive in any environment. And as much as there are good bacteria, a surprisingly large number of them cause more harm than good.
To determine if a surface is contaminated with bacteria, you can try growing the sample from the surface in a petri dish. If the petri dish becomes visibly contaminated (or produces an offensive odor), then the surface you got the sample from is contaminated.
How to Test for Bacteria on Surfaces
Preparing The Petri Dish
Bacteria needs nutrients to grow. So after you’ve gotten your empty petri plate, mix some nutrients (about 5% sheep’s blood should do) with sterile agar, heat it up and pour into the petri dish. Note that plain agar itself is a gelatin-like substance that can be used by bacteria to grow – but allowing them to feed on the plain agar will render the medium unobservable.
After you’ve put the nutrient-agar mixture in petri dishes, refrigerate it unside down – with the cover at the bottom. This is to prevent condensation from forming and dripping onto the agar surface. Now that you’re done with this, you can move on to the testing phase.
Home Test For Bacteria – Direct Contact
You’re trying to test whether a surface is contaminated by pressing whatever surface directly to the petri dish. It could be any household object like a spoon, or even a dirty hand. You’ll need to have the following items closeby:
– a masking tape and marker to label the petri dish
– a petri dish (as prepared above)
– suspected contaminated areas for testing (dirty hands,
food prep areas, etc)
– Bleach
Direct Contact
Step 1. Take out the petri dish from the refrigerator and allow it to come to room temperature (should take about an hour).
Step 2. Gently press the surface to the petri dish. Be careful not to tear the agar surface. Note that certain body parts, like the tongue, just aren’t feasible parts to test for bacteria with direct contact.
Step 3. Put the lid back on the petri dish and clearly label each with the tape and marker, so you know which sample is in which petri plate.
Step 4. Keep the petri dishes upside down again, to prevent condensation, in a room temperate environment.
Step 5. You’ll start noticing
bacteria growth in a few days. Hint, it will start stinking.
Step 6. Keep records of all you’ve observed about bacteria growth from your experiment. You’ll want to pay special attention, during cleaning, to petri dish samples with the most bacteria.
Step 7. Dont just throw away the petri plates when you’re done with your experiment. Pour bleach into the plates to prevent hazardous health effects from the colonies of bacteria you’ve grown. Then dispose of the dishes.
Home Test For Bacteria – Indirect Contact
Step 1. Follow step 1 & 2 above, but instead of using a direct contact with the sample surface, use a sterilized swap to get samples (different swap for different locations) from whatever location you want to test, and then streak the swap against the petri dish.
You can differentiate the petri dish into four quadrants and streak the same sample across each quadrant – with the first quadrant being the most concentrated.
Step 2. Observe the remaining steps above (3 to 7).
Final Thoughts
It’s quite easy to know how to test for bacteria on surfaces in your home. Only critical experients gone wrong will require contacting Bio clean up services. In order to ensure the environment you’re living in is safe, pick your petri plates and start experimenting.
