Biodegradable Affects on the Growth of Yeast

Purpose: to examine gas, as a biodegradable in our eco-system using a yeast and methylene blue system.


1. Using 4 beakers, a combination of methylene blue and water, we diluted the methylene blue to a 1/27 dilution.

             We filled beaker 1 with 200mL of water, and the other 3 beakers we filled with 100mL. We then added 20 drops of methylene blue to beaker 1. Taking 100mL of the solution from beaker 1, we added it to beaker 2. We continued this process by taking 100mL from beaker 2 and adding it to beaker 3, and then taking 100mL from beaker 3 and adding it to beaker 4. This created the perfect dilution for our experiment.

2. We filled 6 test tubes labeled A, B, C, D, E, and F with 10mL of the 1/27 dilution of methylene blue.

            We then started our gas dilution. We followed the same steps as we did with the methylene blue, except we used 50 drops of gas instead of 20 drops.

3. To test tube A we added 10mL of our methylene blue solution.

4. To test tube B we added 10mL of our methylene blue solution and one full dropper of activated yeast.

5. To test tube C, D, E, and F we added 10mL of our methylene blue solution, and one full dropper of yeast. To test tube C we added our highest concentration of gas and water. To test tube D we added our second highest concentration of gas and water. To test tube E we added our third highest concentration of gas and water. Finally, to test tube F we added our lowest concentration of gas and water.

6. We covered the test tubes with corks and waited to see the change in the colour.


See table below vvvv


In this project we used gas as a biodegradable to see how it would affect the growth of yeast. We followed specific steps to get a final result that showed us that the gas enabled the growth of the yeast. The test tubes that had the gas and yeast solution went clear, which indicates that it let the yeast grow. The issues we faced while conducting this experiment were the following: not understanding how to do the experiment, and how much of each material we needed to complete a proper dilution. Improvements that we think our group could make is adding more methylene blue, since our experiment worked so quickly. A next step that we could take is using more test tubes to find the best dilution, whether it be smaller or bigger. We know that gas is bad for our water because it enables the growth of yeast. This is bad because if it's in our water systems it will enable plants to grow and they will take up all the oxygen which will result in the death of living species underwater. Our experiment happened so quickly that the oxygen was used up in matter of 2 hours. If this was to happen in our water systems, underwater species would die sooner. For next steps we can use more test tubes which will allow us to a larger dilution series and we will be able to find the perfect ratio of methylene blue to yeast to gas.

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