Expression Of Astaxanthin Biosynthesis Relates Genes In Haematococcus pluvialis.

Abstract

The unicellular green alga, Haematococcus pluvialis is used as a biological production system for astaxanthin. It accumulates large amounts of the red ketocarotenoid astaxanthin when exposed to various environmental stress situations such as the addition of active oxygen species and high light intensities. To induce astaxanthin biosynthesis of H. pluvialis, cells were incubated in either nitrate free at 25℃ under continuous high light intensity (1000 μEㆍm-2ㆍs-1) for 2 day or/and cells were incubated with methyl viologen (MV). Under these stress conditions, pigment changes and photosynthetic capacity were monitored by using HPLC and pulse-amplitude-modulated (PAM) methods. In addition, we have cloned 5 different peroxiredoxin (Prx) genes of H. pluvialis, and several biosynthesis of astaxanthin genes such as carotenoid hydroxylase, phytoene desaturase, beta-carotene C-4 oxygenase, IPP isomerase and beta-carotene ketolase. Northern and RT-PCR were employed to dissect the molecular mechanism of astaxanthin accumulation under these stress conditions. We observed that Prxs and astaxanthin biosynthesis genes were differentially expressed under different stress conditions compared to normal growth condition.