Enhancement of astaxanthin production from Haematococcus pluvialis under autotrophic growth conditions by a sequential stress strategy.

The study of microalgal culture has been growing in recent decades, because the cellular structure of microalgae has diverse highly valuable metabolites that have attract attention of numerous companies and research groups. The pigment astaxanthin is considered one of the most powerful antioxidants in nature. The microalga Haematococcus pluvialis was proposed as one of the best natural astaxanthin sources, because it can accumulate high amount of the pigment. In this work, we studied different stress treatments on H. pluvialis growth cultures as well as astaxanthin production under autotrophic growth conditions. The results showed that extending nitrogen starvation before increasing radiation intensity up to 110 μmol photons m s during late the palmella cell phase incremented the astaxanthin concentration up to 2.7% of dry biomass with an efficient light energy utilization during the stress stage.