Does Nitrogen Have an Effect on the Growth Rate of chlorella vulgaris?

Abstract

The balance of nutrients such as phosphorus, potassium, and most importantly nitrogen plays a large role in algae production.  Due to algae containing lipids and having the ability to be produced in smaller areas, it can be used to help make biofuels. Because of this, our group came up with a hypothesis that states if we use urea as an additive to grow our algae, then the group of algae with the highest amount of the urea will have the highest cell growth in the chlorella vulgaris, because urea is a nitrogen based substance. In order to test our hypothesis, a photobioreactor was built to test 4 water samples that each received 40 microliters of growth media and 4mL of algae. Out of those 4 water samples, 2 of those samples were given 40 μl of urea. To collect the most accurate data, we used 4 trials for each water sample and ran the experiment twice for a total of 8 trials, four of them being the control and four of them containing urea. We have found that our results do not support our hypothesis since the control groups that did not receive 40ml of urea had a larger cell count average than the groups that received 40ml of urea. This means that the urea delayed the cell growth rather than increasing the cell growth as predicted in our hypothesis. If given the chance, we would be interested to continue our studies to see if different concentration levels of urea would play a role in cell growth rate.