Publisher Summary This chapter focuses on the overproduction of lutein and zeaxanthin in unicellular green microalgae (i.e., Dunaliella salina) cultivated in a photobioreactor exposed to high-intensity light. Growth and productivity of photosynthetic cells within the photobioreactor are affected by many physicochemical and biological factors. Certain requirements of photobioreactors, including the need for strict control of oxygen accumulation, efficient light intensity, and cooling make these systems more expensive to build and operate than open ponds. Thus, despite their advantages, the use of photobioreactors is limited to production of very high value compounds from phototrophs that cannot be cultured in open ponds. In the photobioreactor experiments, O2, CO2, and light are considered as the pivotal design and scale-up parameters. Perfluorocarbon emulsions are used to internally purge out the accumulated inhibitor—oxygen—within the airlift tubular photobioreactor for the enhancement of microalgal production. Stressful culture conditions—high levels of irradiance and high concentrations of CO2—are harnessed to induce the mass production of high-value commercial xanthophyll products (i.e., lutein and zeaxanthin), which play a role in reducing the risk of age-related macular degeneration.