ABSTRACT
This review points out the need to pay attention to the secondary metabolites produced by microalgal extremophiles and their genomes. Microalgal extremophiles produce phenolic compounds as secondary biosynthetic pathways, which leads to the identification of triterpenes, flavonoids, and sterols, and even nonhaline plants. Hypersaline plants serve as a potent source for carotenopids; Halobacterium salinarium is a source of dyes for artificial retinas. The uniqueness of Galderia sulfuraria is discussed; this alga grows photoautotrophically, mixotrophically, and heterotrophically and is resistant not only to acid (pH 0) and heat (56°C), but also to high salt (1.5 M NaCl), toxic metals, and many other abiotic stressors. Mesotaenium berggrenii, an alga that thrives in glaciers, has a purporogallin-carboxylic acid-6-O-b-D-glucopyranoside brownish tannin-like pigment that serves as an analogous protective pigment. It is pointed out that massive sequencing of genomes and transcriptomes of algae, such as Exiguobacterium pavilionensis, would provide insight not only into their survival mechanism, but also for genetic manipulation for biotechnological application.
