en Molecular Microbiology Molecular Microbiology مقاله کامل Full Length/Original Article <strong>Background:</strong> Obesity is a complex disorder influenced by various genetic and environmental factors. It has been shown that gut microbiota, which colonizes gastrointestinal tract, has a substantial role as an environmental factor in the pathophysiology of obesity. Since the composition of gut microbiota alters with regard to different criteria, such as ethnicity, geographical location, diet, lifestyle, age, and gender, we aimed to determine firmicutes/bacteroidetes (F/B) ratio and the abundance of important gut microbiota members, <em>Akkermansia muciniphila</em>, <em>Faecalibacterium prausnitzii, </em><em>Roseburia, Bifidobacterium</em>, and<em> Prevotella</em> in Iranian obese and normal weight individuals, for the first time. <strong>Methods:</strong> In this study, 50 normal and 50 obese subjects were recruited and classified based on their BMI into normal weight and obese groups. Stool samples were collected. Following DNA extraction from the samples, quantitative PCR was conducted based on 16s rDNA universal primers. Finally, the correlation between the bacterial abundance and obesity was analyzed by statistical analyses. <strong>Results</strong>: We observed a significant increase of F/B ratio in the obese group, compared to the normal weight group (<em>p </em>= 0.002). Although <em>A. muciniphila </em>(<em>p</em> = 0.039) and<em> Bifidobacterium </em>(<em>p </em>= 0.049) abundance significantly decreased, the abundance of <em>F. prausnitzii</em> (<em>p </em>= 0.046) significantly elevated with BMI increase in the studied groups. <strong>Conclusion:</strong> Owing to the importance of the gut microbiota composition in obesity development, determination and targeted restoration of gut microbiota pattern could be valuable in the control and treatment of obesity in certain populations. Bacteroidetes, Bifidobacterium, Faecalibacterium prausnitzii, Firmicutes, Microbiota 148 154 http://ibj.pasteur.ac.ir/browse.php?a_code=A-10-1-808&slc_lang=en&sid=1 Fateme Ettehad Marvasti 0000-0001-9192-4919 No Microbiology Research Centre, Pasteur Institute of Iran, Tehran, Iran Arfa Moshiri 0000-0001-8030-0190 No Research Centre for Gastroenterology and Liver Diseases, Shahid Beheshti University of Medical Sciences, Tehran, Iran Mina Sadat Taghavi 0000-0001-9375-3252 No The Islamic Azad University, Science and Research Branch, Tehran, Iran Soheil Riazi 0000-0002-2136-2890 No The Islamic Azad University, Science and Research Branch, Tehran, Iran Majid Taati 0000-0003-1190-6441 No The Islamic Azad University, Science and Research Branch, Tehran, Iran Seyedeh Fatemeh Sadati 0000-0003-1426-3736 No The Islamic Azad University, Science and Research Branch, Tehran, Iran Azadeh Ghaheri 0000-0003-4530-4596 No Departments of Epidemiology and Reproductive Health, Reproductive Epidemiology Research Center, Royan Institute for Reproductive Biomedicine, ACECR, Tehran, Iran Morteza Masoomi 0000-0002-6182-0980 No Microbiology Research Centre, Pasteur Institute of Iran, Tehran, Iran Farzam Vaziri 0000-0001-7788-2548 No Microbiology Research Centre, Pasteur Institute of Iran, Tehran, Iran Abolfazl Fateh 0000-0002-2043-8523 No Microbiology Research Centre, Pasteur Institute of Iran, Tehran, Iran Pejman Rohani 0000-0002-7221-3801 No Department of Pediatric Gastroentrology and Hepatology, Mofid Children's Hospital, Shahid Beheshti University of Medical Sciences, Tehran, Iran Samira Tarashi 0000-0002-7141-322X No Microbiology Research Centre, Pasteur Institute of Iran, Tehran, Iran Andrea Masotti 0000-0002-2511-5088 No Research Laboratories, Bambino Gesù Children's Hospital-IRCCS, Rome, Italy Sara Ahmadi Badi 0000-0001-8679-1277 No Microbiology Research Centre, Pasteur Institute of Iran, Tehran, Iran Seyed Davar Siadat 0000-0002-6892-5603 Yes Microbiology Research Centre, Pasteur Institute of Iran, Tehran, Iran