Mineral oil may impede maximum growth rates and exacerbate carbon dioxide build-up inChlamydomonas reinhardtii

Abstract

Chlamydomonas reinhardtii is a photosynthetic unicellular green algae. Due to its relatively simple genome, C. reinhardtii is a model organism for observing various biological processes. This study focused on how mineral oil impacted its growth rate, since mineral oil prevents gas exchange from occurring on water surfaces. We expected both change in CO₂ concentration (Δ[CO2]) of the media and maximum growth rate to decrease throughout the duration of the experiment. We had four different experimental groups containing equal amounts of C. reinhardtii in each with different volumes of mineral oil added: 0 μL (control group), 250 μL, 500 μL, and 1000 μL. A one-way ANOVA (d.f. = 3, F = 3.32) on maximum growth rates yielded p = 0.115 (α = 0.05), so we failed to observe any significant difference in the maximum growth rates of C. reinhardtii. Additionally, a one-way ANOVA (d.f. = 3, F = 2.13) yielded p = 0.175 for Δ[CO2] , so we also failed to see any significant differences in the Δ[CO2]. Despite the results, the maximum growth rate may have shown a decline as more oil was added, but Δ[CO2] may have shown an increasing trend with increasing amounts of mineral oil. We believe multiple sources of errors may have played a role in the results that we obtained as they did not match with our prediction.