Volume 14, Issue 7 (Supplementary Issue - 2012)
Abstract
Dunaliella is a green halotolerant microalga, which has several industrial applications e.g. β-carotene production. Identification of different Dunaliella species has been carried out by morpho-physiological and recently molecular studies. To achieve an improved understanding of taxonomy, these studies are required to be in linkage. The present study describes molecular and specific morpho-physiological properties of a Dunaliella isolate obtained from Gavkhooni salt marsh in Iran. Phylogenetic analysis of Internal Transcribed Spacer region demonstrated that the isolate was associated with different species except D. salina (CCAP 19/18 and 19/30) and D.viridis. 18S rDNA size of the isolate was identical to that of D. tertiolecta and intron-lacking strains of D. salina. 18S rDNA fingerprint profile and phylogenetic analysis revealed D. tertiolecta as the closest taxon to the isolate. Features of optimum growth salinity (1.5-3% w/v) and maximum carotenoid per cell (0.7 pg cell-1) were comparable with reported data for D. terrtiolecta. Morphological characteristics including the size and color of the cells, presence and location of stigma and refractile granules were similar to those of D. tertiolecta. Totally, considering molecular and morpho-physiological properties, the isolate was attributed to the species D. tertiolecta and was named as Dunaliella tertiolecta ABRIINW-G3.
Volume 18, Issue 6 (11-2016)
Abstract
As the world’s second saltiest lake, Urmia Lake is the main source of halotolerant unicellular microalga, Dunaliella, in Iran. Recently, this lake and, consequently, its biodiversity are being threatened environmentally. Hence collecting, preserving, and identification of indigenous microorganisms of the lake are of great importance. The objective of the present study was the molecular screening of Dunaliella isolates in Urmia Lake. For this purpose, 32 samples were taken from different geographical regions of the lake. Then, their molecular pattern was examined based on 18S rDNA gene and intron-sizing method. Results based on conserved and species-specific primers of 18S rDNA illustrated that, depending on the various parts of the lake, the genetic variation of Dunaliella population differs. The amplified pattern for individual isolates was similar to that previously described for D. tertiolecta, D. bardawil and Dunaliella sp. ARIINW-M1/2. Also,18S rDNA sequencing and phylogenetic analysis of five index isolates showed that the isolates Dunaliella sp. ABRIINW-Ch5, -Sh6.3 and -U1/1 were grouped with different intron lacking species of Dunaliella, ABRIINW-Ch3.1 was clustered with Dunaliella sp. ABRIINW-M1/2, while the isolate Dunaliella sp. ABRIINW-S1.5 was clustered with intron-harboring species of D. bardawil, D. parva, and D. viridis. The results indicated that Urmia Lake is composed of isolates with different 18S rDNA profiles with various intron arrangement.
