Pigments from Eustigmatophyceae: an interesting class of microalgae for carotenoid production

Abstract

Pigments are a fundamental part of the microalgal cell, with chlorophylls at the center of photosynthesis and carotenoids as accessory pigments. The characteristic pigment profile of the Eustigmatophyceae was one of the evidences which contributed to the segregation of this class of organisms from the Xanthophyceae. Recent findings indicate that eustigmatophyte carotenoids are interesting compounds with laboratory-scale proven health-promoting effects but only a few studies dedicate to the characterization of the pigment profile of the class. In the present work, extracts of 27 eustigmatophyte strains held at the Coimbra Collection of Algae (ACOI) were prepared and analyzed by HPLC-DAD. Results showed a typical eustigmatophyte pigment profile present in all strains, namely, chlorophyll a, violaxanthin, vaucheriaxanthin diester, β,β-carotene, and other minor carotenoids. Violaxanthin was the most abundant carotenoid, achieving nearly half the total pigment content in Monodopsis unipapilla ACOI 2938, and also in two studied Vischeria strains, representing ca. 70% of carotenoids in both strains. The second major carotenoid was β,β-carotene, with the highest production of this commercially important carotenoid detected in Pseudostaurastrum sp. ACOI 3413 (24% of total pigments. Characiopsis cf. saccata ACOI 481 and Characiopsis minuta ACOI 2423 had the highest amount of vaucheriaxanthin diester (19% of total pigments). To our best knowledge, this represents the first report where the pigment profile of eustigmatophytes with stipitate Characiopsis-like morphology is characterized. The results reveal the high potential use of eustigmatophytes as sources of naturally derived carotenoids.