Polyethylenimine linked with chitosan improves astaxanthin production in Haematococcus pluvialis

Astaxanthin is receiving increasing interest as an antioxidant and high value-added secondary metabolite. Haematococcus pluvialis is the main source for astaxanthin production, and many studies are being conducted to increase the production of astaxanthin. In this study, we linked polyethylenimine (PEI) with chitosan to maintain astaxanthin-inducing ability while securing the recyclability of the inducer. Astaxanthin accumulation in H. pluvialis was induced to 86.4 pg cell(-1) with the PEI-chitosan fiber (PCF) treatment prepared by cross-linking of 10 mu M PEI and low molecular weight (MW) chitosan via epichlorohydrin. PEI concentration affected the astaxanthin accumulation, whereas the MW of chitosan did not. In addition, the PCF treatment in H. pluvialis increased the reactive oxygen species (ROS) content in cells, thereby upregulating the transcription of enzymes involved in astaxanthin biosynthesis. PCF can be reused multiple times with the maintenance of over 90% of the astaxanthin production efficiency. This study offers a reusable PCF stimulation strategy for enhancing natural astaxanthin content, and PCF treatment will easily increase the production scale or reduce production costs by using recyclability that is not available in current methods.

Automated summary

In this study, the researchers successfully increased the production of astaxanthin in Haematococcus pluvialis by combining polyethylenimine (PEI) with chitosan. The polyethylenimine concentration had an effect on astaxanthin accumulation, while the molecular weight of chitosan did not. The treatment also increased the reactive oxygen species content in cells, leading to the upregulation of enzymes involved in astaxanthin biosynthesis. The PEI-chitosan fiber treatment showed high recyclability and maintained over 90% astaxanthin production efficiency.