Characterization of Dark Cycle of Chlorella sorokiniana

Abstract

Concerns about climate change and depleting fossil fuel reserves have increased the need to find the efficient alternative source of energy. Over the years, algal biofuel research has received great attention and growth and physiological experiments solely on the productivity during the day has extensively been studied. In this research, the effect of light intensities and temperature on the growth pattern and biomass loss during night respiration of Chlorella sorokiniana was investigated. The experiments were conducted at light intensity of 234 μmol m-2 s-1, 134 μmol m-2 s-1 and 108 μmol m-2 s-1 and temperatures ranging from 20 ℃- 40 ℃. Assessment of growth during the complete batch cycle demonstrates the sawtooth pattern of growth which suggests that the percentage cell loss during night respiration has a tremendous negative impact on the overall biomass productivity which in turn impacts the biofuel yield. The experimental results demonstrate that the growth rate defined by the biomass accumulation during the linear phase was highest at high light intensities and at a temperature ranging between 25-32 ℃. Analysis of the night respiration cycle suggests that the loss of biomass is least when the cultures are grown at 134 μmol m-2 s-1 and 25℃. Overall analysis of the growth pattern during the day and the biomass loss during the night shows that the percentage loss in biomass was highest during the linear phase which suggests that temperature and light intensity play a huge role in the cultivation of algae.