Gut microbiota are microorganisms that inhabit the gut; they coexist peacefully with the host, thereby contributing to the health and well-being of individuals. Bacteroidetes and Firmicutes largely dominate the gut microbial flora. The intestinal flora promotes intestinal mucosal integrity, provides essential nutrients such as vitamins and enzymes, protects the body against pathogens and produces antimicrobial peptides such as defensins, C-type lectins, cathelicidins, they also play an active role in the innate and adaptive immune system. Gut microbial flora plays an active role in the synthesis of short-chain fatty acids such as butyrate, propionate and acetate. Gut microbiota also plays a significant role in the cognitive and behavioural functions of the host. A balanced gut microbiota shifts to dysbiosis, due to intake of high fat or sugar or other factors like sedentary lifestyle. The dysbiosis of the gut results in increased permeability, endotoxaemic, insulin resistant, systemic inflammation, adiposity and metabolic disorders such as type 2 diabetes mellitus, non-alcoholic fatty liver disease, non-alcoholic steatohepatitis, irritable bowel disorder, colorectal cancer, etc. A prudent lifestyle modification, added on with use of probiotics and prebiotic restore the normal flora of the gut, especially in patients with Clostridium difficle-associated diarrhoea, inflammatory bowel syndrome, liver disease and colon cancer. Faecal microbial transplant is an important therapeutic tool in many illness related with the gut. Thereby, understanding the gut microbial signatures in various diseases yields various novel therapeutic targets. Human gut microbiota has a prognostic, diagnostic and therapeutic potential which is recognised worldwide.

中文翻译：

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肠道微生物群及其奥秘。


肠道微生物群是居住在肠道中的微生物。它们与宿主和平共处，从而促进个人的健康和福祉。拟杆菌门和厚壁菌门在很大程度上主导着肠道微生物菌群。肠道菌群促进肠粘膜完整性，提供必需营养素，如维生素和酶，保护身体免受病原体侵害，并产生抗菌肽，如防御素、C型凝集素、抗菌肽，它们还在先天性和适应性免疫系统中发挥积极作用。肠道微生物菌群在丁酸、丙酸和乙酸等短链脂肪酸的合成中发挥着积极作用。肠道微生物群在宿主的认知和行为功能中也发挥着重要作用。由于摄入高脂肪或糖或久坐的生活方式等其他因素，平衡的肠道微生物群会转变为菌群失调。肠道菌群失调会导致通透性增加、内毒素血症、胰岛素抵抗、全身炎症、肥胖和代谢紊乱，如2型糖尿病、非酒精性脂肪肝、非酒精性脂肪性肝炎、肠易激性疾病、结直肠癌等。谨慎的生活方式改变，加上益生菌和益生元的使用，可以恢复肠道的正常菌群，特别是对于患有艰难梭菌相关腹泻、炎症性肠综合征、肝病和结肠癌的患者。粪便微生物移植是许多与肠道相关疾病的重要治疗工具。因此，了解各种疾病中的肠道微生物特征可以产生各种新的治疗靶点。人类肠道微生物群具有全世界公认的预后、诊断和治疗潜力。