The aim of this experiment is to test two different concentrations of Dettol disinfectant in limiting soil (sand) bacteria growth.
I think that the concentrations with the most Dettol disinfectant will stop bacterial growth the most. Out of all the percentages I think the 100% disinfectant will stop the bacteria the most, this solution would be made from 10ml of Dettol disinfectant and 0ml of water.
The independent variable in this experiment are the amounts of Dettol disinfectant used for each petri dish, the dependant variables are the measurement of bacterial growth that grows during the time and the controlled variables are everything we kept the same such as the amounts of agar solution, the beaker size, same sized petri dishes, same soil and same sized filter papers.
• Dettol disinfectant
• Measuring cylinders
• Petri Dishes
• Filter paper
• Sticky tape
1- Collect the Dettol disinfectant and water quantities based on the concentration you were given to make. Use 10Ml measuring cylinders.
2- Prepare your disinfectant concentrations into 100mL beakers.
3- Prepare soil and water together allowing soil to settle at the bottom, the pour 10mL of this water without getting any of the soil into the beaker, get rid of the remaining soil and water.
4- Collect a beaker of 50mL full of agar from your teacher and then mix the 10mL of soil water with the agar carefully.
5- Pour the agar/soil water into the petri dishes evenly.
6- Allow the agar to cool and set.
7- Soak your small disk of filter paper into the disinfectant concentration, let it soak for about 10 minutes.
8- Once soaked, place the filter paper into the middle of the agar plate carefully, close the lid and seal with sticky tape, label your petri dish and return it to your teacher.
9- Leave petri dish for a few days in the incubator.
10- Collect your results.
With the results of the agar plates we can see that the solution with the most disinfectant (100%) had hardly any bacterial growth at all, where the (0%) solution with no disinfectant had lots and lots of bacterial growth. Most of the other solutions had growths also, my given solution of 75% had small amounts of bacteria around the outside of the agar plates. The main growths of bacteria occurred around the edge of the filter papers.
Each bacterial growth grew in small shapes and sizes with no pattern in the middles; there was a very strong smell that could be smelt from about 20cm away from the petri dish.
Surprisingly enough there was a significant difference in bacterial growth with the 50% and the 75% since there Is only 25% disinfectant difference. The 50% solution had a lot more bacterial growth compared to the 75% that had only small amounts.
I observed that the agar plates grew bacteria over a number of days for all of the agar plate experiments even with the 100% bacterial Dettol and no other Parts to the...