Different Stresses on Enhancing Astaxanthin Production byHematococcus pluvialis: Investigation Stress-Induced Factors inred aplanospore stages - A Review

Astaxanthin is a xanthophyll carotenoid that possesses stronger antioxidant properties than othercarotenoids. Among the natural producers of astaxanthin (including various microorganisms, microalgalspecies, and animals), the most effective producer is the unicellular microalgae Haematococcus Pluvialis.H.pluvialis is a freshwater microalga with a two-stage life cycle. The first stage is green, wheregreen(macrozooid) motile cells reproduce, and the second stage is red (aplanospore), where astaxanthinaccumulation occurs. The transition from the green to the red phase occurs when cells are environmentallystressed. The bioaccumulation of Astaxanthin in H. pluvialis cysts is a complex process that mainly includesspecific abiotic stress applications. Stress-inducing factors are typically used to induce astaxanthinbiosynthesis and increase its yield in microalgae. This article provides a review of astaxanthin production inH. pluvialis, such as the most critical and common stress strategies to increase astaxanthin accumulation inmicroalgae and investigating various factors in enhancing astaxanthin production under such stressfulconditions.