Effect of varying light intensity on cell abundance of Chlamydomonas reinhardtii

Abstract

Chlamydomonas reinhardtii is a unicellular alga often used as a model organism in various studies involving cell cycle control. A number of factors are involved in the reproduction of these unicellular organisms, including light intensity. Previous research has demonstrated that light intensity influences the growth, abundance and metabolic processes of cells. This paper investigates the effect of light intensity on abundance of C. reinhardtii. Three groups of the organism with four replicates in each were exposed to three different intensities of light including 5000 Lux, 970 Lux and 0 Lux. The experimental setup was kept for 7 days, with alternating periods of 14 hours of light and 10 hours of dark. The abundance of C. reinhardtii was measured on the first, 3rd, 6th, and 8th day of the experiment (t=0, 2, 5, 7). The results indicated an initial decrease in abundance of all treatments. The 5000 Lux and 0 Lux treatments experienced an increase in abundance after t=2. The 970 Lux treatment group underwent an increase in abundance after t=5. The unexpected results obtained in t=5 could be due to changes in metabolic rates of the organism, sample contamination, mutation, and adaptation to changes in energy sources. There is also the possibility of C. reinhardtii undergoing photooxidative stress.