Enhanced production of astaxanthin in a microalga Haematococcus pluvialis NIES-144

Abstract

Astaxanthin is a ketocarotenoid, which is used as a feed supplement in aquaculture for the production of salmon, trout, shrimp as well as a colorant for egg yolk in the poultry industry. In nature, astaxanthin occurs in aquatic crustaceans, yeast, bacteria but natural pigment sources have relatively low content of astaxanthin. The alga Haematococcus pluvialis NIES-144 has a high concentration of astaxanthin ranging from 0.2-2% (w/v) depending on the method and control of culture. The aims of the present study are to culture Haematococcus pluvialis NIES-144 by two-stage batch culture technique. The first-stage, to attain a high cell concentration and for the second-stage, to enhance astaxanthin formation. Haematococcus pluvialis NIES-144 could grow best in the Basal Medium with 1.5 g/l sodium acetate and 3.0 g/l yeast extract, initial cell number of 2x10x10x10x10x10 cell per ml under light intensity of 30 micro Em[superscript -2]s[superscript -1], 12-hlight at 20 ํC. The cell concentration of up to 5.6x10x10x10x10x10 cell per ml was obtained. The optimal condition for astaxanthin accumulation in Haematococcus pluvialis NIES-144 was obtained by cultivation in Basal Medium at 20 ํC under 30 micro Em[superscript -2]s[superscript -1] continuous illumination with the supplementation of 45 mM sodium acetate and was able to produce 7.41 mg/l of astaxanthin. The analysis of astaxanthin was performed by HPLC using C18 column with dichloromethane : methanol : acetonitrile : water solvent systems. Astaxanthins content were found to account for 75% of total carotenoids.