Isolation and molecular identification of Dunaliella salina (Chlorophyceae) cyst from sediments of the Lipar coast (Oman Sea)

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.