Abstract
A method for determining provitamin A in Euglena gracilis Z was proposed by using high performance liquid chromatography (HPLC) and the culture conditions of E. gracilis for high yield of provitamin A were studied.
1) Direct saponification of Euglena cells with 3.2 M KOH in methanol at 60°C for 20 min gave a satisfactory recovery of provitamin A.
2) Saponified extract of Euglena cells was loaded onto a column packed with silicagel and eluted with different solvents. From the absorption maximum and retention time in HPLC the Euglena provitamin A was found to be consisted of β-carotene, echnenone and euglenanone.
3) The content of β-carotene in the wild strain of E. gracilis grown with illumination was 577.8 μg/109 cells. The wild strain grown in the dark and the bleached strain (a mutant derived from the wild strain) grown with or without illumination did not give higher contents.
4) Among several carbon sources examined, glucose or malic acid gave high yield of β-carotene in culturing E. gracilis. The highest content of β-carotene was obtained by culturing Euglena in the Koren-Hutner medium containing glucose and malic acid as the major carbon sources.
