A strategy for promoting astaxanthin accumulation in Haematococcus pluvialis by 1-aminocyclopropane-1-carboxylic acid application

- The effect of ACC, a precursor of ethylene, to promote astaxanthin was examined.
- ACC could enhance the growth of Haematococcus pluvialis, thereby promoting astaxanthin accumulation.
- Gene expressions related with astaxanthin biosynthesis were thoroughly examined.
- Cellular extent of reactive oxygen species (ROS) were monitored in response to the treatment of ACC.
- A direct treatment of ethylene originated from banana peels verified the effect of ACC.

The green algae Haematococcus pluvialis is a freshwater unicellular microalga belonging to Chlorophyceae. It is one of the best natural sources of astaxanthin, a secondary metabolite commonly used as an antioxidant and anti-inflammatory agent. Due to the importance of astaxanthin, various efforts have been made to increase its production. In this study, we attempted to develop a strategy for promoting astaxanthin accumulation in H. pluvialis using 1-aminocyclopropane-1-carboxylic acid (ACC), a precursor of ethylene (normally known as an aging hormone in plants). Our results demonstrated that ACC could enhance the growth of H. pluvialis, thereby promoting astaxanthin accumulation. Therefore, ACC has an indirect influence on astaxanthin production. We further verified the effect of ACC with a direct treatment of ethylene originated from banana peels. These results indicate that ethylene could be applied as an indirect method for enhancing growth and astaxanthin biosynthesis in H. pluvialis.