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 Some species of phytoplankton under unfavorable environmental conditions and in their sexual life cycle produce resting cyst that settle to the bottom sediments and become motile in the water column when suitable conditions provided. Phytoplankton species were studied in two stages of motile and cyst for accurate identification of morphology, because some similar cysts may convert to a different phytoplankton and vice versa. The objectives of this study were to culture cysts that isolated from sediments of Lipar zone located in the southeast coast of Iran and to identify excysted samples. Sediment samples from Lipar zone were collected by Ekman grab with 225 cm² area in 2015. Unknown live and orbicular single cysts were isolated from sediments and cultured in sterile conditions in phycolab using f₂ medium under 12 hours light and 12 hours dark cycles at 25±1°C. Assessment of excysted plankton morphology revealed that the cyst is belonged to Dunaliella salina species. In order to confirm this morphological identification, DNA of the plankton was extracted and PCR was performed. The sequence of the sample was compared with the sequences of the similar species from GenBank. Phylogeny and molecular analysis confirmed this identification. The present study revealed that D. salina from the south coast of Iran was able to produce resting cyst.
 

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This study investigated the growth performance and fatty acid composition of Western whiteleg shrimp (Litopenaeus vannamei) fed with different levels of Dunaliella salina extract (DE) PL with an average weight of 0.86 ± 0.01g were fed with 3 types of diets containing 0.5, 1.5 and 1.5 g DE /kg diet and control diet (without DE) for 60 days. (A total of 4 treatments and 3 repetitions per treatment). The best weight gain (141.38 ± 21.35%), specific growth ratio (1.69 ± 0.55%) and protein efficiency ratio (2.79± 0.42%) were observed in shrimp fed with 1 g/kg of DE diet. In diets containing 0.5 and 1 g DE/kg feed, poly unsaturated fatty acid (PUFA) value significantly increased (p<0.05). Arachidonic acid (C20:4n-6), linoleic acid (C20:2n-6) and Docosahexaenoic acid (C22:5n-3) levels of shrimp receiving at 0.5 and 1 g DE/kg feed level were significantly higher than those fed with control diet(p<0.05). In conclusion, the incorporation of extract from D.salina 1 g/kg doses improves function of growth and fatty acid composition of body in L. vannamei shrimp.

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Today, microalgae are considered as an important source for the production of biofuels and pharmaceutical products. However, the lack of an efficient and economical method for dewatering and harvesting their biomass is is an important challenge to achieve this goal. The important issue for choosing the harvesting method are species characteristics, final product value and energy consumption. Therefore, in this study, the effect of flocculation method with pH change technique (range 6 to 11) using sodium hydroxide and hydrogen chloride on harvesting efficiency, and fatty acid content of Dunaliella salina was tested. The results of this study showed that with the addition of sodium hydroxide and increasing the pH from 8.2 to 9.8, the flocculation process increased upwards from 18 to 90% and then remained constant until: pH 11. In contrast, increasing hydrogen chloride and creating an acidic environment up to: pH equal to 6 had no effect on clot stimulation. The highest coefficient of biomass concentration was observed in alkaline treatment with pH: equivalent to 9.8 which was 10 times the initial concentration (at pH equal to 8.2 the effect of alkaline pH induction technique and the centrifuge technique on the fatty acids content of biomass was tested. In the next stage, the effect of alkaline pH induction technique and the centrifuge technique on the fatty acids content of biomass was tested. The analysis showed that the percentage of lipid and fatty acids of harvested biomass were significantly different from each other. Based on the obtained results, the flocculation method by increasing the pH by 9.8 is a simple and relatively inexpensive technique with high efficiency and is suitable for harvesting Dunaliella salina microalgae for specific purposes.
 

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In this study, growth, biomass, concentration of chlorophyll a chlorophyll b, and carotenoid content of Dunaliella salina were evaluated in five different treatment (including: T1: 35 ppt (freshwater + salt), T2: 20 ppt (freshwater + salt), T3: 35 ppt (deep aquifer well water+ salt), T4: 35 ppt (concentrated deep aquifer well water), and T5: 20 ppt (deep aquifer well water)) in the same conditions, including the amount of light intensity (33.75 μmol.m².s¹) Photoperiodic lighting (16 hours of light:8 hours of dark), the temperature at (25±1 degrees centigrade), pH (8), cultivation medium (modified Johnson medium), and the same 24-hour aeration for 24 days. The results showed that among different treatments, the lowest pH fluctuation was observed in the T3, T4, and T5. In addition, T3, T4, and T5 had a better situation in terms of growth, and growth rate was increased until the 21st day of the experiment. Maximum cellular yield (R) for T3, T4, and T5 was recorded on day 21, which was 9 days longer than other groups (T1 & T2). The Minimum cell number, minimum optical density (OD), minimum specific growth rate (SGR), minimum doubling time (DT), minimum dry biomass, and maximum Division per day (k) were recorded for T2. The maximum dry biomass was observed in T4. The highest and lowest mean of chlorophyll a concentration appeared in T4 and T2, respectively. While the maximum and minimum mean of chlorophyll b level was recorded in T2 and T1, respectively. The highest and lowest mean of carotenoids concentration was obtained in T1 and T2, respectively. Based on the results of this study, the cultivation of D.salina with deep aquifer well water is possible.