REAPPRAISAL OF PHYSIOLOGICAL ATTRIBUTES OF NINE STRAINS OF DUNALIELLA (CHLOROPHYCEAE): GROWTH AND PIGMENT CONTENT ACROSS A SALINITY GRADIENT

Abstract

Among the few taxonomic characters used to circumscribe sections within the subgenus Dunaliella are the physiological response to changes in salt concentration, which define a specific range for optimal growth, and the carotenogenic ability of the vegetative cells, responsible for the change in cell color from green to orange or red, under suboptimal culture conditions. Previous work based on molecular data from seven taxa of different sections of the subgenus showed no correlation between the genetic relationship inferred from the internal transcribed spacer RFLP data and the morphophysiological attributes in use in taxonomy. The present work was performed to experimentally reevaluate the physiological attributes in the same seven previous taxa ( D. tertiolecta Butcher UTEX 999 and CCMP 1320, D. parva Lerche UTEX 1983 and CCMP 362, D. salina Teodoresco UTEX 200, D. viridis Teodoresco CONC 002, and D. peircei Nicolai et Baas Becking UTEX 2192) adding D. parva CCAP 19/9 and D. pseudosalina Massyuk et Radchenko CONC 010. Growth responses and pigment content in a wide range of NaCl concentrations were assessed. The results revealed that two strains of D. parva , two strains of D. tertiolecta , and one strain of D. peircei showed similarity in their growth responses to the whole range of salt concentrations. Dunaliella parva UTEX 1983, on the other hand, showed a growth rate pattern very different from those of their conspecifics and similar to those of D. viridis CONC 002 and D. salina UTEX 200. In relation to the pigment content, none of the strains turned orange or red in color under the whole range of salt concentrations assayed, and the total carotenoids to chlorophyll ratios were always lower or equal to 1.0. These results reaffirm the validity of the physiological attributes used to discriminate sections within the subgenus Dunaliella and show correlation with the previous molecular data, but stress the need for relocating some strains into different sections.

Propyl gallate promotes salt stress tolerance in green microalga Dunaliella salina by reducing free radical oxidants and enhancing β-carotene production

“…In agreement with our results, previous studies on D. salina showed that maximum Chl a content is observed at 3 M NaCl (Mishra et al 2008). Similar results were also obtained in D. tertiolecta grown at 3 M NaCl (Cifuentes et al 2001;Fazeli et al 2006). It has also been observed that in higher plants such as tomato, concentration of 0.3 M NaCl stimulates Chl production per unit leaf area (Agong et al 2004).…”

Microalgal biotechnology: Carotenoid and glycerol production by the green algae Dunaliella isolated from the Gave-Khooni salt marsh, Iran

“…D. salina had the highest carotenoid/chlorophyll ratio (2.58) at 4 M NaCl (Table 2). These results are in accordance with the reports of Cifuentes et al[14] and Gomez et al[15]. Glycerol production in D. salina and D. viridis grown in different salt concentrations are shown inFigs.…”

Characterization of Dunaliella salina strains by flow cytometry: a new approach to select carotenoid hyperproducing strains

“…González et al (1998) showed a low intraspecific genetic variability in strains from different countries. However, an important correspondence among intraspecific genetic variability and morphological and physiological behaviour has been found in D. salina, though the morphologic traditional criteria of taxonomical classification present diverse limitations (Cifuentes et al 2001;Gómez and González, 2001;González et al 2001). In the present work, it can be underlined the wide morphological and physiological variation found among native strains isolated from various saltworks in close geographical vicinity.…”