# Enhancement of astaxanthin accumulation via energy reassignment by removing the flagella of Haematococcus pluvialis

## TL;DR

Removing flagella from Haematococcus pluvialis increases astaxanthin production by redirecting energy.

## Contribution

This study reveals that flagella removal enhances astaxanthin accumulation through energy reassignment.

## Key findings

- Flagella removal increased astaxanthin content by up to 91.1% compared to controls.
- Cells without flagella showed higher NADPH levels and altered photosynthetic parameters.
- Energy is redirected from movement to astaxanthin biosynthesis when flagella are absent.

## Abstract

Astaxanthin biosynthesis in Haematococcus pluvialis is driven by energy. However, the effect of the flagella-mediated energy-consuming movement process on astaxanthin accumulation has not been well studied. In this study, the profiles of astaxanthin and NADPH contents in combination with the photosynthetic parameters with or without flagella enabled by pH shock were characterized. The results demonstrated that there was no significant alteration in cell morphology, with the exception of the loss of flagella observed in the pH shock treatment group. In contrast, the astaxanthin content in the flagella removal groups was 62.9%, 62.8% and 91.1% higher than that of the control at 4, 8 and 12 h, respectively. Simultaneously, the increased Y(II) and decreased Y(NO) suggest that cells lacking the flagellar movement process may allocate more energy towards astaxanthin biosynthesis. This finding was verified by NADPH analysis, which revealed higher levels in flagella removal cells. These results provide preliminary insights into the underlying mechanism of astaxanthin accumulation enabled by energy reassignment in movement-lacking cells.