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 19 th century to the thorough taxonomic studies by Teodoresco, Hamburger, Lerche and others from the beginnig of the 20 th 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.

Exploring biodegradable polymer production from marine microbes

“…Some haloalkaliphilic bacteria such as Natronococcus occultus and N. gregoryi use 2-sulfotrehalose instead of KCl to some extent to counterbalance these external stimuli when cultured in nutrient limited medium [102]. The second adaptation is similar to that of the earlier one whereas bacteria and eukarya maintain low concentration of salt by accumulating low molecular weight organic compounds known as osmolytes [100,101]. Osmolytes are compatible solutes which are mostly amino acids, derivatives, sugars, or polyols that by and large do not interfere in the metabolism of the cell.…”

“…Most halophiles grow at optimum cell growth and tolerate 5−10 % (w/v) salt concentration [100]. Halophiles are found in all the three domains of life; they basically adapt two different metabolic pathways to survive on this high salt concentration; the first is to regulate concentrations of KCl with that of NaCl in the external environment, thus maintaining the osmotic pressure and enhancing survival [100,101]. Some haloalkaliphilic bacteria such as Natronococcus occultus and N. gregoryi use 2-sulfotrehalose instead of KCl to some extent to counterbalance these external stimuli when cultured in nutrient limited medium [102].…”

“…Most halophiles grow at optimum cell growth and tolerate 5−10 % (w/v) salt concentration [100]. Halophiles are found in all the three domains of life; they basically adapt two different metabolic pathways to survive on this high salt concentration; the first is to regulate concentrations of KCl with that of NaCl in the external environment, thus maintaining the osmotic pressure and enhancing survival [100,101].…”

“…This osmolyte facilitates retaining turgor pressure, cell dimensions, and the concentration of electrolytes that are vital for the cell to be biologically active [101]. Halophilic bacteria include a huge number of phylogenetic groups akin to cyanobacteria, spirochetes, and actinomycetes, where some of them can withstand NaCl concentration of 30 % (w/v) [100].…”

Microalgae, a Potential Natural Functional Food Source – a Review

“…Some Chlorella strains have a cell wall with a trilaminar (TLS) outer layer that contains algaenan, a resistant and non-hydrolysable biopolymer, while other strains have a cell wall with no TLS outer layer, but a high percentage of polysaccharides. In contrast, the Chlorophyta Dunaliella salina lacks a rigid cell wall [Busi et al, 2014;Oren, 2005, Chen et al, 2011.…”