Impact of Cell Size, Light Wavelengths, and Intensities on Growth, Oxygen Production, and Consumption Rates of Chromochloris zofingiensis and Haematococcus lacustris.

Chromochloris zofingiensis ( C. zofingiensis ) and Haematococcus lacustris ( H. lacustris ) were cultivated in an autotrophic conditions. The algae cell sizes were measured to determine their size and light absorption for oxygen production and consumption rates. Methodologies were developed to measure the oxygen production and consumption rates of both species using different light wavelengths (blue and red) and intensities (20–80 µmol m ^–2 s ^–1 ). H. lacustris , with larger cells, potentially exhibited slower growth rates (0.09 d ^–1 ) at 20 µmol m ^–2 s ^–1 in blue-light and high O ₂ consumption in the red-light, which resulted in an increase in pH (11.8) at 80 µmol m ^–2 s ^–1 in red-light. Conversely, C. zofingiensis was distinguished by smaller, non-motile cells, which streamlined oxygen production, transport, and responded favorably to changes in blue-light intensities, with a higher specific growth rate of 0.19 d ^–1 . Both algae species had high oxygen production and consumption rates in blue-light environment due to its short wavelength. While in the blue-light environment, C. zofingiensis optimized its photosynthetic quotient (2.3) at 60 µmol m ^–2 s ^–1 . This study underscores the biotechnological potential of C. zofingiensis as an oxygen source and high-value products.