A hundred years of Dunaliella research: 1905-2005

Abstract

A hundred years have passed since the description of the genus Dunaliella, the unicellular green alga which is responsible for most of the primary production in hypersaline environments worldwide. The present paper provides an historical survey of research on Dunaliella, from the early work in the 19th century to the thorough taxonomic studies by Teodoresco, Hamburger, Lerche and others from the beginning of the 20th century onwards. It attempts to trace the origin of some of the most important breakthroughs that have contributed to our present understanding of this alga that plays such a key role in many hypersaline environments.

Figure 1

Dunaliella salina cells from the crystallizer brine of the salterns in Eilat, at the Red Sea coast of Israel.

Figure 2

Drawings by Hamburger (1905) of red cells (Dunaliella salina) (1–4) and green cells (D. viridis) (5–8), diverse shapes observed in a drop that becomes more concentrated by evaporation (9–29), spherical forms obtained upon dilution (30–31), and initiation of cell division (32–34). From [2].

Figure 3

Dunaliella salina (1–17) preserved with different fixation techniques; (3), pigment crystals; (8), granules (starch?); (10–13), division stages; (14,15), aplanospores; (16–17), and green cells (D. viridis?), as drawn by Hamburger (1905) [7].

Figure 4

Aggregation of the red and the green form of Dunaliella salina (upper part) and zygote formation of D. salina (green and red form) (lower part). From [30].

Figure 5

Division rate ("Teilungsrate") (as number of divisions per day) of different Dunaliella isolates belonging to several species, as a function of the NaCl concentration of the medium. From [30].