结直肠癌（CRC）是世界上第三大常见癌症，结肠癌发生是一种涉及环境和遗传因素的多因素疾病。肠道微生物群在调节肠道稳态中发挥着关键作用。越来越多的证据表明肠道微生物群在结直肠癌的发展中发挥着重要作用，并可能成为早期诊断的生物标志物。本研究旨在通过宏基因组分析确定土耳其人群结直肠癌患者肠道微生物群的临床预后意义，并确定微生物组成肿瘤组织活检样本中。在结肠镜检查期间用无菌镊子从参与者身上采集组织活检并储存在-80°C。然后，从组织样本中分离 DNA，并在 Illumina MiSeq 平台上对 16 S rRNA 基因的 V3-V4 区域进行测序。对获得的序列数据进行质量控制。操作分类单位（OTU）根据 Greengenes 数据库进行分类。进行了α多样性（香农指数）和β多样性（布雷-柯蒂斯距离）分析。确定了 CRC 患者和健康对照中最常见的细菌种类，并测试了组间是否存在统计学显着差异。我们的宏基因组研究共纳入了 40 名个体、13 名 CRC 患者和 20 名健康对照个体。患者的平均年龄为64.83岁，BMI为25.85。在CRC患者中，门分类中拟杆菌的水平显着升高（p = 0.04），类分类中梭状芽胞杆菌的水平显着升高（p = 0.23），属分类中肠球菌的水平显着升高（ p = 0.01）。 CRC患者与对照组相比，在物种分类中检测到Gemmiger formicilis (p = 0.15)、Prevotella copri (p = 0.02)和Ruminococcus bromii (p = 0.001)的种类显着增加。肠道宏基因组分析CRC 患者的微生物群组成为确定这些患者的治疗方案提供了重要数据。这项研究的结果表明，它可能有益于 CRC 患者的早期诊断、不良预后和生存率。此外，这项宏基因组研究是第一项针对土耳其人群中与结直肠癌粘膜相关的结肠微生物组的研究。© 2024。作者获得韩国遗传学会的独家许可。

Colorectal cancer (CRC) is the 3rd most common cancer in the world and colonic carcinogenesis is a multifactorial disease that involves environmental and genetic factors. Gut microbiota plays a critical role in the regulation of intestinal homeostasis. Increasing evidence shows that the gut microbiome plays a role in CRC development and may be a biomarker for early diagnosis.This study aimed to determine the clinical prognostic significance of gut microbiota in CRC patients in the Turkish population by metagenomic analysis and to determine the microbial composition in tumor tissue biopsy samples.Tissue biopsies were taken from the participants with sterile forceps during colonoscopy and stored at -80 °C. Then, DNA isolation was performed from the tissue samples and the V3-V4 region of the 16 S rRNA gene was sequenced on the Illumina MiSeq platform. Quality control of the obtained sequence data was performed. Operational taxonomic units (OTUs) were classified according to the Greengenes database. Alpha diversity (Shannon index) and beta diversity (Bray-Curtis distance) analyses were performed. The most common bacterial species in CRC patients and healthy controls were determined and whether there were statistically significant differences between the groups was tested.A total of 40 individuals, 13 CRC patients and 20 healthy control individuals were included in our metagenomic study. The mean age of the patients was 64.83 and BMI was 25.85. In CRC patients, the level of Bacteroidetes at the phylum taxonomy was significantly increased (p = 0.04), the level of Clostridia at the class taxonomy was increased (p = 0.23), and the level of Enterococcus at the genus taxonomy was significantly increased (p = 0.01). When CRC patients were compared with the control group, significant increases were detected in the species of Gemmiger formicilis (p = 0.15), Prevotella copri (p = 0.02) and Ruminococcus bromii (p = 0.001) at the species taxonomy.Metagenomic analysis of intestinal microbiota composition in CRC patients provides important data for determining the treatment options for these patients. The results of this study suggest that it may be beneficial in terms of early diagnosis, poor prognosis and survival rates in CRC patients. In addition, this metagenomic study is the first study on the colon microbiome associated with CRC mucosa in the Turkish population.© 2024. The Author(s) under exclusive licence to The Genetics Society of Korea.