In this study, the use of pH
shock to improve
astaxanthin synthesis in Haematococcus lacustris was investigated. It has been found that pH
shock (pH = 4.5, 60 s) imposes stress in the cells and induces physiological changes, which result in
astaxanthin accumulation. The optimal
acid-base combination of pH
shock was H2SO4-KOH, which increased the
astaxanthin content per cell to 39 ± 6.92% than those of the control. In addition, pH
shock can be applied simultaneously with the other inductive strategies such as high irradiance and
carbon source supply. When high irradiance was applied simultaneously with pH
shock,
astaxanthin yield was increased 65 ± 0.541% than control. In addition,
astaxanthin content per cell was increased 105 ± 6.66% than those of the control, with the concomitant application of
carbon source addition with pH
shock. Herein, these novel findings provide a useful technique for producing
astaxanthin using H. lacustris.