Tehran University of Medical Sciences Iranian Journal of Microbiology 2008-3289 6 6 2014 12 15 437 442 EN Raheem Haddad Department of Agricultural Biotechnology, Faculty of Engineering and Technology, Imam Khomeini International University, Qazvin, Iran. Esmat Alemzadeh Department of Agricultural Biotechnology, Faculty of Engineering and Technology, Imam Khomeini International University, Qazvin, Iran. Ali Reza Ahmadi Department of Biomedical Sciences, Alzahra University, Tehran, Iran. Ramin Hosseini Department of Agricultural Biotechnology, Faculty of Engineering and Technology, Imam Khomeini International University, Qazvin, Iran. Maryam Moezzi Persian Gulf & Oman Sea Ecological Research Institute, Bandar Abbas, Iran. 2015 10 16 Background and Objectives: Chlorophyceae are important constituents of marine phytoplankton. The taxonomy of Chlorophyceae was traditionally based solely on morphological characteristics. In the present research project, genetic diversity was investigated to analyze five species of Chlorophyceae from waters of the Persian Gulf. Materials and Methods:  A clone library of the ribosomal small subunit RNA gene (18S rDNA) in the nuclear genome was constructed by PCR, and then, after examining the clones, selected clones were sequenced. The determined clone sequences were analyzed by a similarity search of the NCBI GenBank database using BLAST. Results and Conclusion: Eleven sequences were identified correctly and used for phylogenetic analysis. We identified species of Chlorophyta (Chlorella sorokiniana, Chlamydomonas sp., Neochloris aquatic, Picochlorum sp. and Nannochloris atomus) without the need to conduct extensive colony isolation techniques. Therefore, this improved molecular method can be used to generate a robust database describing the species diversity of environmental samples. https://ijm.tums.ac.ir/index.php/ijm/article/view/359 https://ijm.tums.ac.ir/index.php/ijm/article/download/359/136