Bacteria’s Growth Affected by Various Glucose Percentages This lab tested whether or not different glucose levels activated bacteria growth. My lab group and I wanted to figure out, if more glucose was spread on the bacteria plates, would there be more bacteria growth in the agar plate. My group predicted that with 25% glucose (the highest percentage of glucose), the bacteria growth would be the greatest. In order to conduct this experiment, my group had 3 ager plates. One plate had 0% glucose, the next plate had 5% glucose and the third plate had 25% glucose in it.
Once we received all the plates, we light an alcohol burner. We then used a pipet to sterile collect bacteria from the culture tubes. We then opened the first ager plate (0% glucose) and transferred 10 drops of bacteria culture onto the plate. Then we did the same for the next 2 plates (5% and 25% glucose). Next, we sterilized the spreader by waving it in the flame (alcohol burner) for 15 seconds. Then, we let the spreader cool for 10 seconds, and then opened the first agar plate and spread the bacteria around the plate by quickly and slightly sliding the spreader back and forth across the plate for 5 seconds.
Then we closed the plate and did the same thing for the next 2 plates. Next, we sealed each plate with a strip of Para film and then placed the plates with bacteria on the side of the room until the following week. After waiting a week, we received our group’s ager plates back. We noticed that with our experiment, the most amount of bacteria growth had no glucose in it. Our results were the following: with no glucose, there was 25% bacteria growth, with 5% glucose added to the ager plates, there was only 15% bacteria growth, and with 25% glucose added to the ager plates, only 1% of bacteria growth was present.
The least amount of bacteria growth contained the largest percentage of glucose. Based off of our group’s results, we can reject our hypothesis. We realized that our prediction was not what our results showed us. Our prediction was that 25% glucose would have the most amount of bacteria growth, however we can now conclude that bacteria growth does not need any glucose to reproduce. In fact, the more glucose there is, the least amount of bacteria growth occurs. If glucose is present in the bacteria, it is possible for bacteria to reproduce; however bacteria will reproduce the greatest when no glucose is present at all.